Spine

ABSTRACT

We conducted a study to determine the common characteristics of patients who developed radiculopathy symptoms and corresponding heterotopic ossification (HO) from transforaminal lumbar interbody fusions (TLIF) using recombinant human bone morphogenetic protein 2 (rhBMP-2). HO can arise from a disk space with rhBMP-2 use in TLIF. Formation of bone around nerve roots or the thecal sac can cause a radiculopathy with a consistent pattern of symptoms.

We identified 38 patients (26 males, 12 females) with a mean (SD) age of 50.8 (7.5) years who developed radiculopathy symptoms and corresponding HO from TLIF with rhBMP-2 in the disk space between 2002 and 2015. To document this complication and improve its recognition, we recorded common patterns of symptom development and radiologic findings: specifically, time from implantation of rhBMP-2 to symptom development, consistency with side of TLIF placement, and radiologic findings.

Radicular pain generally developed a mean (SD) of 3.8 (1.0) months after TLIF with rhBMP-2. Development of radiculopathy symptoms corresponded to consistent “pseudo-pedicle”-like HO. In all 38 patients, HO arising from the annulotomy site showed a distinct pseudo-pedicle pattern encompassing nerve roots and the thecal sac. In addition, development of radiculopathy symptoms and corresponding HO appear to be independent of amount of rhBMP-2. HO resulting from TLIF with rhBMP-2 in the disk space is a pain generator and a recognizable complication that can be diagnosed by assessment of symptoms and computed tomography characteristics.

Continue to: Bone morphogenetic proteins...

 

Bone morphogenetic proteins (BMPs), first isolated by Urist in 1964¹, are a family of growth factors that stimulate the cascade of bone formation. Recombinant human BMP (rhBMP), specifically rhBMP-2 and rhBMP-7 (also known as osteogenic protein 1 [OP-1]), was developed in the 1990s after the advent of gene splicing. Then, in 2002, the US Food and Drug Administration (FDA) approved use of rhBMP to stimulate fusion in the human spine. Specifically, rhBMP-2 (Medtronic) was approved for use in combination with a specific brand of interbody cage in 1-level anterior lumbar interbody fusion.² Over the past decade, off-label use of rhBMP-2 to achieve osseous union has increased dramatically, particularly in spinal surgery: transforaminal lumbar interbody fusion (TLIF), posterior lumbar interbody fusion, and posterolateral lumbar fusion.^3-9 However, this widespread off-label use for posterior spinal fusion began despite FDA data indicating that specific complications were underreported in the peer-reviewed literature.^10,11 Although rhBMP-2 is very effective in increasing osteoblast formation and improving osteogenesis and subsequent bone healing in spinal surgery,^12,13 its use in TLIF resulted in significant adverse side effects, including radiculopathy with and without neuroforaminal heterotopic ossification (HO); ^14-24 complications in the FDA studies; ^14,22,25-27 and osteolysis causing intervertebral cage subsidence, inflammatory radiculitis, genitourinary complications, infections, possible systemic effects, and significant HO complications.^10,28-30 Of these, HO complications involved rhBMP leakage through the annulotomy to the disk space that led to HO. Specifically, rhBMP leaked directly out of the disk space and formed a pillar of bone that encased the nerve roots and dura, which led to occlusion of the foramen and symptoms of radiculopathy.^10,28-30

Despite this frequent finding of HO in the intervertebral space outside the target fusion area, use of rhBMP-2 with intervertebral cages increased so rapidly that rhBMP-2 was used more often than autologous bone.^5,11,17,31 In this study, we reviewed the common characteristics of patients who developed HO and subsequent radiculopathy from TLIF with rhBMP.

METHODS

After this study received Institutional Review Board approval, we retrospectively reviewed cases of radiculopathy symptoms that developed after TLIF with rhBMP between January 2002 and January 2015. During this period, 38 patients (26 males, 12 females) with a mean (SD) age of 50.8 (7.5) years and radiculopathy symptoms arising from TLIF with rhBMP-2 were identified to determine commonalities and defining characteristics that will help facilitate diagnosis.

Inclusion criteria were computed tomography (CT)–documented HO arising from the TLIF annulotomy site in continuity with bone in the disk space or ectopic bone forming a distinctive shell with contouring around the thecal sac or nerve roots, as well as recurrence or initial occurrence of radiculopathy with signs and symptoms corresponding to the CT site of aberrant bone growth in terms of laterality and particular nerve root(s) involved. Exclusion criteria were malplacement of interbody cage or pedicle screws, disk herniation, systemic neuropathic disease, and new or unresolved radiculopathy immediately after index surgery.

To improve recognition of this complication, we also documented the amount of BMP used, common patterns of radiculopathy symptom development, and radiologic findings. Type and timing of radiculopathy symptom onset and consistency with side of TLIF placement were documented as well. Radiculopathy symptoms included shooting pain in the legs, incontinence, sexual dysfunction, and severe paralysis. Radiologic findings were specific to bone formation from the disk space (detected with CT).

Continue to: RESULTS

 

 

RESULTS

All 38 selected patients had radiculopathy symptoms from HO out of the intervertebral space. The Table lists the patients’ overall characteristics. The left side had the most radiculopathy symptoms (31/38 patients), followed by the right side (5/38) and both sides (2/38). Radiculopathy symptoms began a mean (SD) of 3.8 (1.0) months (range, 2-6 months) after index surgery. The 38 patients had 4 characteristics in common:

Table. Transforaminal Lumbar Interbody Fusion With Recombinant Human Bone Morphogenetic Protein 2: Onset Time for Radiculopathy Symptoms, Surgery Level, Side of Pseudo-Pedicle Bone Formation, and Subsequent Complications

Pt	Sympton Onset, mo	Surgery Level(s)	Side(s)	Complication(s)
1	3	L3-L5 (2)	Both	Radiculopathy, pseudo-pedicle, urine
2	3	L4-L5 (2)	R	Radiculopathy, pseudo-pedicle
3	4	L5-S1 (1)	R	Radiculopathy, pseudo-pedicle
4	5	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
5	4	L4-S1 (2)	L	Radiculopathy, pseudo-pedicle, subsidence
6	5	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
7	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
8	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
9	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
10	2	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
11	2	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, subsidence, neurologic
12	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
13	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, neurologic
14	2	L2-L3 (1)	R	Radiculopathy, pseudo-pedicle
15	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
16	3	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
17	3	L2-L3, L4-L5 (2)	L	Radiculopathy, pseudo-pedicle
18	3	L4-L5, L2-L3 (1)	L	Radiculopathy, pseudo-pedicle, nonunion
19	4	L4-L5 (1)	R	Radiculopathy, pseudo-pedicle
20	5	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
21	5	L5-S1 (1)	R	Radiculopathy, pseudo-pedicle
22	3	L3-L4, L5-S1 (2)	Both	Radiculopathy, pseudo-pedicle
23	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
24	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
25	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
26	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, urine, bowel
27	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
28	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
29	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
30	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
31	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
32	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
33	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
34	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
35	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
36	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
37	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
38	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle

1. Bone growing out of the annulotomy site for TLIF cage placement was present and in continuity with the disk space in 33 (87%) of the 38 cases. In the other 5 cases (13%), HO was present around the neural tissue, but not necessarily in continuity with the disk space. This bone appeared ectopic and not osteophytic and facet-related, as it formed a shell around either the nerve root or the thecal sac, contouring to the structure.

2. The common, novel finding on CT was a “pseudo-pedicle” (Figures 1A, 1B), which appeared as ectopic growth from the disk space—a solid piece of bone in the same direction as the anatomical pedicle. Confusing similarity to the anatomical pedicle is present on axial cuts and during surgery. The pseudo-pedicle varied in thickness and extent out of the disk space, but was always presented as a bar of bone arising from the annulotomy site. After arising from the disk space, the HO could disperse in any direction, further calcifying neural structures or the facet joints above or below. There was no apparent distinguishable repeating pattern, given the variable nature of arthritic facet changes, scoliotic deformities, size of annulotomies, amount of rhBMP used, and placement in cage and disk space or only in cage.

3. In 36 (95%) of the 38 cases, the initial interpretation of HO on magnetic resonance imaging (MRI) was of tissue other than bone, such as fibrous tissue, granulation tissue, recurrent disk herniation, or postoperative changes. However, this tissue was later determined to be bone from HO complications, which we confirmed with CT in all 38 cases. It is important to note that HO on MRI (Figures 2A, 2B) was initially interpreted by a radiologist as fibrous tissue, but same-level CT of the same case (Figures 3A, 3B) showed clear HO.

4. The radiculopathy symptoms caused by HO were independent of the amount of rhBMP-2 used in TLIF. Of the 38 patients, 19 had 1 rhBMP-2 sponge placed in the cage, 12 had a small kit sponge (1.05 mg), 5 had 1 sponge placed in the cage and 1 sponge placed directly in the disk space before cage placement (no notation of precise size or amount of rhBMP-2), and 2 had 1 sponge placed in the cage (no notation of rhBMP-2 amount). The data showed that HO can occur with even a small amount of rhBMP-2.

Continue to: Bone formation with rhBMP-2...

 

Bone formation with rhBMP-2 is robust and beneficial, but HO-related complications are significant, and identifiable on assessment of radiculopathy symptoms and CT characteristics.

DISCUSSION

We identified 38 patients with a recognizable and consistent pattern of complications of off-label use of rhBMP-2 in TLIF performed at our institution between 2002 and 2015. This pattern included consistent radiculopathy symptoms with corresponding HO at the annulotomy site in continuity with bone in the disk space or ectopic bone forming a distinctive shell around the thecal sac or nerve roots, as well as showing a distinct pseudo-pedicle pattern encompassing nerve roots and the thecal sac. Our finding differs from other findings of similar complication characteristics, but with much larger variations without consistency within the patient population.^19,20,22,24 Specifically, previous studies found an association between off-label rhBMP-2 use in the posterior spine and radiculopathy with and without neuroforaminal HO. However, our study found consistent radiculopathy symptoms with pseudo-pedicle-like HO complications in all its 38 patients a mean (SD) of 3.8 (1.0) months after surgery.

In this study, consistent radiculopathy symptoms with pseudo-pedicle-like HO complications were independent of the amount of rhBMP-2 used, as some complications occurred with use of small pack rhBMP-2 with TLIF. It is well understood that high doses of rhBMP-2 may be required to improve fusion rates, but to our knowledge an optimal dosing strategy for TLIF has not been reported, particularly with respect to potential complications.^8,20,31-33 For anterior lumbar interbody fusion surgery, the FDA-approved use of rhBMP-2 appears to have a significantly decreased risk of neuroforaminal HO complications. This may be attributable to the protective presence of the intact posterior annulus and longitudinal ligament for this procedure.^20,33 For TLIF, it has been suggested that rhBMP-2 should be placed only along the anterior annulus with a posterior strut and morselized bone allograft barricade,³³ and that fibrin glue should be used to limit BMP diffusion through the annulotomy site³¹ to prevent this complication.

Our study results suggest that radiculopathy symptoms with pseudo-pedicle-like HO complications appear to be caused by leakage of rhBMP-2 from the disk space through the annulotomy site. This was often initially interpreted incorrectly on MRI in the first year after surgery as being fibrous or granulation tissue, or even postoperative changes that the heterotopic tissue was bone was obvious only on CT. Even then the tissue may be incorrectly identified, as the encasing nerve roots in bone are similar to the scar tissue having no compressive effect. HO may compress, but it also has an inflammatory component that the scars lack. Additionally, the HO from the disk space, caused by leakage of the BMP placed in or around the fusion cage, can create a pseudo-pedicle of varying size and extent. This was present in all 38 of our cases.

This retrospective case series had its limitations. Its clinical and radiographic findings were not blinded. Confounding variables cannot be isolated for causal relationships, if any, to the complication in a case series such as this.

Bone formation with rhBMP-2 is robust and beneficial, but HO-related complications are significant, and identifiable on assessment of radiculopathy symptoms and CT characteristics.

ABSTRACT

We conducted a study to determine the common characteristics of patients who developed radiculopathy symptoms and corresponding heterotopic ossification (HO) from transforaminal lumbar interbody fusions (TLIF) using recombinant human bone morphogenetic protein 2 (rhBMP-2). HO can arise from a disk space with rhBMP-2 use in TLIF. Formation of bone around nerve roots or the thecal sac can cause a radiculopathy with a consistent pattern of symptoms.

We identified 38 patients (26 males, 12 females) with a mean (SD) age of 50.8 (7.5) years who developed radiculopathy symptoms and corresponding HO from TLIF with rhBMP-2 in the disk space between 2002 and 2015. To document this complication and improve its recognition, we recorded common patterns of symptom development and radiologic findings: specifically, time from implantation of rhBMP-2 to symptom development, consistency with side of TLIF placement, and radiologic findings.

Radicular pain generally developed a mean (SD) of 3.8 (1.0) months after TLIF with rhBMP-2. Development of radiculopathy symptoms corresponded to consistent “pseudo-pedicle”-like HO. In all 38 patients, HO arising from the annulotomy site showed a distinct pseudo-pedicle pattern encompassing nerve roots and the thecal sac. In addition, development of radiculopathy symptoms and corresponding HO appear to be independent of amount of rhBMP-2. HO resulting from TLIF with rhBMP-2 in the disk space is a pain generator and a recognizable complication that can be diagnosed by assessment of symptoms and computed tomography characteristics.

Continue to: Bone morphogenetic proteins...

 

Bone morphogenetic proteins (BMPs), first isolated by Urist in 1964¹, are a family of growth factors that stimulate the cascade of bone formation. Recombinant human BMP (rhBMP), specifically rhBMP-2 and rhBMP-7 (also known as osteogenic protein 1 [OP-1]), was developed in the 1990s after the advent of gene splicing. Then, in 2002, the US Food and Drug Administration (FDA) approved use of rhBMP to stimulate fusion in the human spine. Specifically, rhBMP-2 (Medtronic) was approved for use in combination with a specific brand of interbody cage in 1-level anterior lumbar interbody fusion.² Over the past decade, off-label use of rhBMP-2 to achieve osseous union has increased dramatically, particularly in spinal surgery: transforaminal lumbar interbody fusion (TLIF), posterior lumbar interbody fusion, and posterolateral lumbar fusion.^3-9 However, this widespread off-label use for posterior spinal fusion began despite FDA data indicating that specific complications were underreported in the peer-reviewed literature.^10,11 Although rhBMP-2 is very effective in increasing osteoblast formation and improving osteogenesis and subsequent bone healing in spinal surgery,^12,13 its use in TLIF resulted in significant adverse side effects, including radiculopathy with and without neuroforaminal heterotopic ossification (HO); ^14-24 complications in the FDA studies; ^14,22,25-27 and osteolysis causing intervertebral cage subsidence, inflammatory radiculitis, genitourinary complications, infections, possible systemic effects, and significant HO complications.^10,28-30 Of these, HO complications involved rhBMP leakage through the annulotomy to the disk space that led to HO. Specifically, rhBMP leaked directly out of the disk space and formed a pillar of bone that encased the nerve roots and dura, which led to occlusion of the foramen and symptoms of radiculopathy.^10,28-30

Despite this frequent finding of HO in the intervertebral space outside the target fusion area, use of rhBMP-2 with intervertebral cages increased so rapidly that rhBMP-2 was used more often than autologous bone.^5,11,17,31 In this study, we reviewed the common characteristics of patients who developed HO and subsequent radiculopathy from TLIF with rhBMP.

METHODS

After this study received Institutional Review Board approval, we retrospectively reviewed cases of radiculopathy symptoms that developed after TLIF with rhBMP between January 2002 and January 2015. During this period, 38 patients (26 males, 12 females) with a mean (SD) age of 50.8 (7.5) years and radiculopathy symptoms arising from TLIF with rhBMP-2 were identified to determine commonalities and defining characteristics that will help facilitate diagnosis.

Inclusion criteria were computed tomography (CT)–documented HO arising from the TLIF annulotomy site in continuity with bone in the disk space or ectopic bone forming a distinctive shell with contouring around the thecal sac or nerve roots, as well as recurrence or initial occurrence of radiculopathy with signs and symptoms corresponding to the CT site of aberrant bone growth in terms of laterality and particular nerve root(s) involved. Exclusion criteria were malplacement of interbody cage or pedicle screws, disk herniation, systemic neuropathic disease, and new or unresolved radiculopathy immediately after index surgery.

To improve recognition of this complication, we also documented the amount of BMP used, common patterns of radiculopathy symptom development, and radiologic findings. Type and timing of radiculopathy symptom onset and consistency with side of TLIF placement were documented as well. Radiculopathy symptoms included shooting pain in the legs, incontinence, sexual dysfunction, and severe paralysis. Radiologic findings were specific to bone formation from the disk space (detected with CT).

Continue to: RESULTS

 

 

RESULTS

All 38 selected patients had radiculopathy symptoms from HO out of the intervertebral space. The Table lists the patients’ overall characteristics. The left side had the most radiculopathy symptoms (31/38 patients), followed by the right side (5/38) and both sides (2/38). Radiculopathy symptoms began a mean (SD) of 3.8 (1.0) months (range, 2-6 months) after index surgery. The 38 patients had 4 characteristics in common:

Table. Transforaminal Lumbar Interbody Fusion With Recombinant Human Bone Morphogenetic Protein 2: Onset Time for Radiculopathy Symptoms, Surgery Level, Side of Pseudo-Pedicle Bone Formation, and Subsequent Complications

Pt	Sympton Onset, mo	Surgery Level(s)	Side(s)	Complication(s)
1	3	L3-L5 (2)	Both	Radiculopathy, pseudo-pedicle, urine
2	3	L4-L5 (2)	R	Radiculopathy, pseudo-pedicle
3	4	L5-S1 (1)	R	Radiculopathy, pseudo-pedicle
4	5	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
5	4	L4-S1 (2)	L	Radiculopathy, pseudo-pedicle, subsidence
6	5	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
7	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
8	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
9	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
10	2	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
11	2	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, subsidence, neurologic
12	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
13	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, neurologic
14	2	L2-L3 (1)	R	Radiculopathy, pseudo-pedicle
15	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
16	3	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
17	3	L2-L3, L4-L5 (2)	L	Radiculopathy, pseudo-pedicle
18	3	L4-L5, L2-L3 (1)	L	Radiculopathy, pseudo-pedicle, nonunion
19	4	L4-L5 (1)	R	Radiculopathy, pseudo-pedicle
20	5	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
21	5	L5-S1 (1)	R	Radiculopathy, pseudo-pedicle
22	3	L3-L4, L5-S1 (2)	Both	Radiculopathy, pseudo-pedicle
23	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
24	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
25	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
26	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, urine, bowel
27	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
28	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
29	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
30	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
31	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
32	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
33	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
34	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
35	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
36	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
37	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
38	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle

1. Bone growing out of the annulotomy site for TLIF cage placement was present and in continuity with the disk space in 33 (87%) of the 38 cases. In the other 5 cases (13%), HO was present around the neural tissue, but not necessarily in continuity with the disk space. This bone appeared ectopic and not osteophytic and facet-related, as it formed a shell around either the nerve root or the thecal sac, contouring to the structure.

2. The common, novel finding on CT was a “pseudo-pedicle” (Figures 1A, 1B), which appeared as ectopic growth from the disk space—a solid piece of bone in the same direction as the anatomical pedicle. Confusing similarity to the anatomical pedicle is present on axial cuts and during surgery. The pseudo-pedicle varied in thickness and extent out of the disk space, but was always presented as a bar of bone arising from the annulotomy site. After arising from the disk space, the HO could disperse in any direction, further calcifying neural structures or the facet joints above or below. There was no apparent distinguishable repeating pattern, given the variable nature of arthritic facet changes, scoliotic deformities, size of annulotomies, amount of rhBMP used, and placement in cage and disk space or only in cage.

3. In 36 (95%) of the 38 cases, the initial interpretation of HO on magnetic resonance imaging (MRI) was of tissue other than bone, such as fibrous tissue, granulation tissue, recurrent disk herniation, or postoperative changes. However, this tissue was later determined to be bone from HO complications, which we confirmed with CT in all 38 cases. It is important to note that HO on MRI (Figures 2A, 2B) was initially interpreted by a radiologist as fibrous tissue, but same-level CT of the same case (Figures 3A, 3B) showed clear HO.

4. The radiculopathy symptoms caused by HO were independent of the amount of rhBMP-2 used in TLIF. Of the 38 patients, 19 had 1 rhBMP-2 sponge placed in the cage, 12 had a small kit sponge (1.05 mg), 5 had 1 sponge placed in the cage and 1 sponge placed directly in the disk space before cage placement (no notation of precise size or amount of rhBMP-2), and 2 had 1 sponge placed in the cage (no notation of rhBMP-2 amount). The data showed that HO can occur with even a small amount of rhBMP-2.

Continue to: Bone formation with rhBMP-2...

 

Bone formation with rhBMP-2 is robust and beneficial, but HO-related complications are significant, and identifiable on assessment of radiculopathy symptoms and CT characteristics.

DISCUSSION

We identified 38 patients with a recognizable and consistent pattern of complications of off-label use of rhBMP-2 in TLIF performed at our institution between 2002 and 2015. This pattern included consistent radiculopathy symptoms with corresponding HO at the annulotomy site in continuity with bone in the disk space or ectopic bone forming a distinctive shell around the thecal sac or nerve roots, as well as showing a distinct pseudo-pedicle pattern encompassing nerve roots and the thecal sac. Our finding differs from other findings of similar complication characteristics, but with much larger variations without consistency within the patient population.^19,20,22,24 Specifically, previous studies found an association between off-label rhBMP-2 use in the posterior spine and radiculopathy with and without neuroforaminal HO. However, our study found consistent radiculopathy symptoms with pseudo-pedicle-like HO complications in all its 38 patients a mean (SD) of 3.8 (1.0) months after surgery.

In this study, consistent radiculopathy symptoms with pseudo-pedicle-like HO complications were independent of the amount of rhBMP-2 used, as some complications occurred with use of small pack rhBMP-2 with TLIF. It is well understood that high doses of rhBMP-2 may be required to improve fusion rates, but to our knowledge an optimal dosing strategy for TLIF has not been reported, particularly with respect to potential complications.^8,20,31-33 For anterior lumbar interbody fusion surgery, the FDA-approved use of rhBMP-2 appears to have a significantly decreased risk of neuroforaminal HO complications. This may be attributable to the protective presence of the intact posterior annulus and longitudinal ligament for this procedure.^20,33 For TLIF, it has been suggested that rhBMP-2 should be placed only along the anterior annulus with a posterior strut and morselized bone allograft barricade,³³ and that fibrin glue should be used to limit BMP diffusion through the annulotomy site³¹ to prevent this complication.

Our study results suggest that radiculopathy symptoms with pseudo-pedicle-like HO complications appear to be caused by leakage of rhBMP-2 from the disk space through the annulotomy site. This was often initially interpreted incorrectly on MRI in the first year after surgery as being fibrous or granulation tissue, or even postoperative changes that the heterotopic tissue was bone was obvious only on CT. Even then the tissue may be incorrectly identified, as the encasing nerve roots in bone are similar to the scar tissue having no compressive effect. HO may compress, but it also has an inflammatory component that the scars lack. Additionally, the HO from the disk space, caused by leakage of the BMP placed in or around the fusion cage, can create a pseudo-pedicle of varying size and extent. This was present in all 38 of our cases.

This retrospective case series had its limitations. Its clinical and radiographic findings were not blinded. Confounding variables cannot be isolated for causal relationships, if any, to the complication in a case series such as this.

Bone formation with rhBMP-2 is robust and beneficial, but HO-related complications are significant, and identifiable on assessment of radiculopathy symptoms and CT characteristics.

ABSTRACT

We conducted a study to determine the common characteristics of patients who developed radiculopathy symptoms and corresponding heterotopic ossification (HO) from transforaminal lumbar interbody fusions (TLIF) using recombinant human bone morphogenetic protein 2 (rhBMP-2). HO can arise from a disk space with rhBMP-2 use in TLIF. Formation of bone around nerve roots or the thecal sac can cause a radiculopathy with a consistent pattern of symptoms.

We identified 38 patients (26 males, 12 females) with a mean (SD) age of 50.8 (7.5) years who developed radiculopathy symptoms and corresponding HO from TLIF with rhBMP-2 in the disk space between 2002 and 2015. To document this complication and improve its recognition, we recorded common patterns of symptom development and radiologic findings: specifically, time from implantation of rhBMP-2 to symptom development, consistency with side of TLIF placement, and radiologic findings.

Radicular pain generally developed a mean (SD) of 3.8 (1.0) months after TLIF with rhBMP-2. Development of radiculopathy symptoms corresponded to consistent “pseudo-pedicle”-like HO. In all 38 patients, HO arising from the annulotomy site showed a distinct pseudo-pedicle pattern encompassing nerve roots and the thecal sac. In addition, development of radiculopathy symptoms and corresponding HO appear to be independent of amount of rhBMP-2. HO resulting from TLIF with rhBMP-2 in the disk space is a pain generator and a recognizable complication that can be diagnosed by assessment of symptoms and computed tomography characteristics.

Continue to: Bone morphogenetic proteins...

 

Bone morphogenetic proteins (BMPs), first isolated by Urist in 1964¹, are a family of growth factors that stimulate the cascade of bone formation. Recombinant human BMP (rhBMP), specifically rhBMP-2 and rhBMP-7 (also known as osteogenic protein 1 [OP-1]), was developed in the 1990s after the advent of gene splicing. Then, in 2002, the US Food and Drug Administration (FDA) approved use of rhBMP to stimulate fusion in the human spine. Specifically, rhBMP-2 (Medtronic) was approved for use in combination with a specific brand of interbody cage in 1-level anterior lumbar interbody fusion.² Over the past decade, off-label use of rhBMP-2 to achieve osseous union has increased dramatically, particularly in spinal surgery: transforaminal lumbar interbody fusion (TLIF), posterior lumbar interbody fusion, and posterolateral lumbar fusion.^3-9 However, this widespread off-label use for posterior spinal fusion began despite FDA data indicating that specific complications were underreported in the peer-reviewed literature.^10,11 Although rhBMP-2 is very effective in increasing osteoblast formation and improving osteogenesis and subsequent bone healing in spinal surgery,^12,13 its use in TLIF resulted in significant adverse side effects, including radiculopathy with and without neuroforaminal heterotopic ossification (HO); ^14-24 complications in the FDA studies; ^14,22,25-27 and osteolysis causing intervertebral cage subsidence, inflammatory radiculitis, genitourinary complications, infections, possible systemic effects, and significant HO complications.^10,28-30 Of these, HO complications involved rhBMP leakage through the annulotomy to the disk space that led to HO. Specifically, rhBMP leaked directly out of the disk space and formed a pillar of bone that encased the nerve roots and dura, which led to occlusion of the foramen and symptoms of radiculopathy.^10,28-30

Despite this frequent finding of HO in the intervertebral space outside the target fusion area, use of rhBMP-2 with intervertebral cages increased so rapidly that rhBMP-2 was used more often than autologous bone.^5,11,17,31 In this study, we reviewed the common characteristics of patients who developed HO and subsequent radiculopathy from TLIF with rhBMP.

METHODS

After this study received Institutional Review Board approval, we retrospectively reviewed cases of radiculopathy symptoms that developed after TLIF with rhBMP between January 2002 and January 2015. During this period, 38 patients (26 males, 12 females) with a mean (SD) age of 50.8 (7.5) years and radiculopathy symptoms arising from TLIF with rhBMP-2 were identified to determine commonalities and defining characteristics that will help facilitate diagnosis.

Inclusion criteria were computed tomography (CT)–documented HO arising from the TLIF annulotomy site in continuity with bone in the disk space or ectopic bone forming a distinctive shell with contouring around the thecal sac or nerve roots, as well as recurrence or initial occurrence of radiculopathy with signs and symptoms corresponding to the CT site of aberrant bone growth in terms of laterality and particular nerve root(s) involved. Exclusion criteria were malplacement of interbody cage or pedicle screws, disk herniation, systemic neuropathic disease, and new or unresolved radiculopathy immediately after index surgery.

To improve recognition of this complication, we also documented the amount of BMP used, common patterns of radiculopathy symptom development, and radiologic findings. Type and timing of radiculopathy symptom onset and consistency with side of TLIF placement were documented as well. Radiculopathy symptoms included shooting pain in the legs, incontinence, sexual dysfunction, and severe paralysis. Radiologic findings were specific to bone formation from the disk space (detected with CT).

Continue to: RESULTS

 

 

RESULTS

All 38 selected patients had radiculopathy symptoms from HO out of the intervertebral space. The Table lists the patients’ overall characteristics. The left side had the most radiculopathy symptoms (31/38 patients), followed by the right side (5/38) and both sides (2/38). Radiculopathy symptoms began a mean (SD) of 3.8 (1.0) months (range, 2-6 months) after index surgery. The 38 patients had 4 characteristics in common:

Table. Transforaminal Lumbar Interbody Fusion With Recombinant Human Bone Morphogenetic Protein 2: Onset Time for Radiculopathy Symptoms, Surgery Level, Side of Pseudo-Pedicle Bone Formation, and Subsequent Complications

Pt	Sympton Onset, mo	Surgery Level(s)	Side(s)	Complication(s)
1	3	L3-L5 (2)	Both	Radiculopathy, pseudo-pedicle, urine
2	3	L4-L5 (2)	R	Radiculopathy, pseudo-pedicle
3	4	L5-S1 (1)	R	Radiculopathy, pseudo-pedicle
4	5	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
5	4	L4-S1 (2)	L	Radiculopathy, pseudo-pedicle, subsidence
6	5	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
7	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
8	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
9	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
10	2	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
11	2	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, subsidence, neurologic
12	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
13	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, neurologic
14	2	L2-L3 (1)	R	Radiculopathy, pseudo-pedicle
15	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
16	3	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
17	3	L2-L3, L4-L5 (2)	L	Radiculopathy, pseudo-pedicle
18	3	L4-L5, L2-L3 (1)	L	Radiculopathy, pseudo-pedicle, nonunion
19	4	L4-L5 (1)	R	Radiculopathy, pseudo-pedicle
20	5	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
21	5	L5-S1 (1)	R	Radiculopathy, pseudo-pedicle
22	3	L3-L4, L5-S1 (2)	Both	Radiculopathy, pseudo-pedicle
23	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
24	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
25	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
26	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle, urine, bowel
27	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
28	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
29	6	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
30	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
31	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
32	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
33	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
34	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
35	4	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
36	3	L5-S1 (1)	L	Radiculopathy, pseudo-pedicle
37	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle
38	4	L4-L5 (1)	L	Radiculopathy, pseudo-pedicle

1. Bone growing out of the annulotomy site for TLIF cage placement was present and in continuity with the disk space in 33 (87%) of the 38 cases. In the other 5 cases (13%), HO was present around the neural tissue, but not necessarily in continuity with the disk space. This bone appeared ectopic and not osteophytic and facet-related, as it formed a shell around either the nerve root or the thecal sac, contouring to the structure.

2. The common, novel finding on CT was a “pseudo-pedicle” (Figures 1A, 1B), which appeared as ectopic growth from the disk space—a solid piece of bone in the same direction as the anatomical pedicle. Confusing similarity to the anatomical pedicle is present on axial cuts and during surgery. The pseudo-pedicle varied in thickness and extent out of the disk space, but was always presented as a bar of bone arising from the annulotomy site. After arising from the disk space, the HO could disperse in any direction, further calcifying neural structures or the facet joints above or below. There was no apparent distinguishable repeating pattern, given the variable nature of arthritic facet changes, scoliotic deformities, size of annulotomies, amount of rhBMP used, and placement in cage and disk space or only in cage.

3. In 36 (95%) of the 38 cases, the initial interpretation of HO on magnetic resonance imaging (MRI) was of tissue other than bone, such as fibrous tissue, granulation tissue, recurrent disk herniation, or postoperative changes. However, this tissue was later determined to be bone from HO complications, which we confirmed with CT in all 38 cases. It is important to note that HO on MRI (Figures 2A, 2B) was initially interpreted by a radiologist as fibrous tissue, but same-level CT of the same case (Figures 3A, 3B) showed clear HO.

4. The radiculopathy symptoms caused by HO were independent of the amount of rhBMP-2 used in TLIF. Of the 38 patients, 19 had 1 rhBMP-2 sponge placed in the cage, 12 had a small kit sponge (1.05 mg), 5 had 1 sponge placed in the cage and 1 sponge placed directly in the disk space before cage placement (no notation of precise size or amount of rhBMP-2), and 2 had 1 sponge placed in the cage (no notation of rhBMP-2 amount). The data showed that HO can occur with even a small amount of rhBMP-2.

Continue to: Bone formation with rhBMP-2...

 

Bone formation with rhBMP-2 is robust and beneficial, but HO-related complications are significant, and identifiable on assessment of radiculopathy symptoms and CT characteristics.

DISCUSSION

We identified 38 patients with a recognizable and consistent pattern of complications of off-label use of rhBMP-2 in TLIF performed at our institution between 2002 and 2015. This pattern included consistent radiculopathy symptoms with corresponding HO at the annulotomy site in continuity with bone in the disk space or ectopic bone forming a distinctive shell around the thecal sac or nerve roots, as well as showing a distinct pseudo-pedicle pattern encompassing nerve roots and the thecal sac. Our finding differs from other findings of similar complication characteristics, but with much larger variations without consistency within the patient population.^19,20,22,24 Specifically, previous studies found an association between off-label rhBMP-2 use in the posterior spine and radiculopathy with and without neuroforaminal HO. However, our study found consistent radiculopathy symptoms with pseudo-pedicle-like HO complications in all its 38 patients a mean (SD) of 3.8 (1.0) months after surgery.

In this study, consistent radiculopathy symptoms with pseudo-pedicle-like HO complications were independent of the amount of rhBMP-2 used, as some complications occurred with use of small pack rhBMP-2 with TLIF. It is well understood that high doses of rhBMP-2 may be required to improve fusion rates, but to our knowledge an optimal dosing strategy for TLIF has not been reported, particularly with respect to potential complications.^8,20,31-33 For anterior lumbar interbody fusion surgery, the FDA-approved use of rhBMP-2 appears to have a significantly decreased risk of neuroforaminal HO complications. This may be attributable to the protective presence of the intact posterior annulus and longitudinal ligament for this procedure.^20,33 For TLIF, it has been suggested that rhBMP-2 should be placed only along the anterior annulus with a posterior strut and morselized bone allograft barricade,³³ and that fibrin glue should be used to limit BMP diffusion through the annulotomy site³¹ to prevent this complication.

Our study results suggest that radiculopathy symptoms with pseudo-pedicle-like HO complications appear to be caused by leakage of rhBMP-2 from the disk space through the annulotomy site. This was often initially interpreted incorrectly on MRI in the first year after surgery as being fibrous or granulation tissue, or even postoperative changes that the heterotopic tissue was bone was obvious only on CT. Even then the tissue may be incorrectly identified, as the encasing nerve roots in bone are similar to the scar tissue having no compressive effect. HO may compress, but it also has an inflammatory component that the scars lack. Additionally, the HO from the disk space, caused by leakage of the BMP placed in or around the fusion cage, can create a pseudo-pedicle of varying size and extent. This was present in all 38 of our cases.

This retrospective case series had its limitations. Its clinical and radiographic findings were not blinded. Confounding variables cannot be isolated for causal relationships, if any, to the complication in a case series such as this.

Bone formation with rhBMP-2 is robust and beneficial, but HO-related complications are significant, and identifiable on assessment of radiculopathy symptoms and CT characteristics.

Take-Home Points

• Studies of AEs after orthopedic surgery commonly use composite AE outcomes.
• These types of outcomes treat AEs with different clinical significance similarly.
• This study created a single severity-weighted outcome that can be used to characterize the overall severity of a given patient’s postoperative course.
• Future studies may benefit from using this new severity-weighted outcome score.

Recently there has been an increase in the use of national databases for orthopedic surgery research.^1-4 Studies commonly compare rates of postoperative adverse events (AEs) across different demographic, comorbidity, and procedural characteristics.^5-23 Their conclusions often highlight different modifiable and/or nonmodifiable risk factors associated with the occurrence of postoperative events.

The several dozen AEs that have been investigated range from very severe (eg, death, myocardial infarction, coma) to less severe (eg, urinary tract infection [UTI], anemia requiring blood transfusion). A common approach for these studies is to consider many AEs together in the same analysis, asking a question such as, “What are risk factors for the occurrence of ‘adverse events’ after spine surgery?” Such studies test for associations with the occurrence of “any adverse event,” the occurrence of any “serious adverse event,” or similar composite outcomes. How common this type of study has become is indicated by the fact that in 2013 and 2014, at least 12 such studies were published in Clinical Orthopaedics and Related Research and the Journal of Bone and Joint Surgery,^5-14,21-23 and many more in other orthopedic journals.^15-20 However, there is a problem in using this type of composite outcome to perform such analyses: AEs with highly varying degrees of severity have identical impacts on the outcome variable, changing it from negative (“no adverse event”) to positive (“at least one adverse event”). As a result, the system may treat a very severe AE such as death and a very minor AE such as UTI similarly. Even in studies that use the slightly more specific composite outcome of “serious adverse events,” death and a nonlethal thromboembolic event would be treated similarly. Failure to differentiate these AEs in terms of their clinical significance detracts from the clinical applicability of conclusions drawn from studies using these types of composite AE outcomes.

In one of many examples that can be considered, a retrospective cohort study compared general and spinal anesthesia used in total knee arthroplasty.¹⁰ The rate of any AEs was higher with general anesthesia than with spinal anesthesia (12.34% vs 10.72%; P = .003). However, the only 2 specific AEs that had statistically significant differences were anemia requiring blood transfusion (6.07% vs 5.02%; P = .009) and superficial surgical-site infection (SSI; 0.92% vs 0.68%; P < .001). These 2 AEs are of relatively low severity; nevertheless, because these AEs are common, their differences constituted the majority of the difference in the rate of any AEs. In contrast, differences in the more severe AEs, such as death (0.11% vs 0.22%; P > .05), septic shock (0.14% vs 0.12%; P > .05), and myocardial infarction (0.20% vs 0.20%; P > .05), were small and not statistically significant. Had more weight been given to these more severe events, the outcome of the study likely would have been “no difference.”

To address this shortcoming in orthopedic research methodology, we created a severity-weighted outcome score that can be used to determine the overall “severity” of any given patient’s postoperative course. We also tested this novel outcome score for correlation with procedure type and patient characteristics using orthopedic patients from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP). Our intention is for database investigators to be able to use this outcome score in place of the composite outcomes that are dominating this type of research.

Methods

Generation of Severity Weights

Our method is described generally as utility weighting, assigning value weights reflective of overall impact to differing outcome states.²⁴ Parallel methods have been used to generate the disability weights used to determine disability-adjusted life years for the Global Burden of Disease project²⁵ and many other areas of health, economic, and policy research.

All orthopedic faculty members at 2 geographically disparate, large US academic institutions were invited to participate in a severity-weighting exercise. Each surgeon who agreed to participate performed the exercise independently.

Each participant was given a stack of 23 index cards, each listing the name and description of an AE monitored by ACS-NSQIP (Table 1).²⁶ In addition, in the upper right corner of each card was a box in which the participant could write a number. Each stack of cards was provided in a distinct randomized order. Written instructions for participants were exactly as follows:

• STEP 1: Please reorder the AE cards by your perception of “severity” for a patient experiencing that event after an orthopedic procedure.
• STEP 2: Once your cards are in order, please determine how many postoperative occurrences of each event you would “trade” for 1 patient experiencing postoperative death. Place this number of occurrences in the box in the upper right corner of each card.
• NOTES: As you consider each AE:
• Please consider an “average” occurrence of that AE, but note that in no case does the AE result in perioperative death.
• Please consider only the “severity” for the patient. (Do not consider the extent to which the event may be related to surgical error.)
• Please consider that the numbers you assign are relative to each other. Hence, if you would trade 20 of “event A” for 1 death, and if you would trade 40 of “event B” for 1 death, the implication is that you would trade 20 of “event A” for 40 of “event B.”
• You may readjust the order of your cards at any point.

Participants’ responses were recorded. For each number provided by each participant, the inverse (reciprocal) was taken and multiplied by 100%. This new number was taken to be the percentage severity of death that the given participant considered the given AE to embody. For example, as a hypothetical on one end of the spectrum, if a participant reported 1 (he/she would trade 1 AE X for 1 death), then the severity would be 1/1 × 100% = 100% of death, a very severe AE. Conversely, if a participant reported a very large number like 100,000 (he/she would trade 100,000 AEs X for 1 death), then the severity would be 1/100,000 × 100% = 0.001% of death, a very minor AE. More commonly, a participant will report a number like 25, which would translate to 4% of death (1/25 × 100% = 4%). For each AE, weights were then averaged across participants to derive a mean severity weight to be used to generate a novel composite outcome score.

Definition of Novel Composite Outcome Score

The novel composite outcome score would be expressed as a percentage to be interpreted as percentage severity of death, which we termed severity-weighted outcome relative to death (SWORD). For each patient, SWORD was defined as no AE (0%) or postoperative death (100%), with other AEs assigned mean severity weights based on faculty members’ survey responses. A patient with multiple AEs would be assigned the weight for the more severe AE. This method was chosen over summing the AE weights because in many cases the AEs were thought to overlap; hence, summing would be inappropriate. For example, generally a deep SSI would result in a return to the operating room, and one would not want to double-count this AE. Similarly, it would not make sense for a patient who died of a complication to have a SWORD of >100%, which would be the summing result.

Application to ACS-NSQIP Patients

ACS-NSQIP is a surgical registry that prospectively identifies patients undergoing major surgery at any of >500 institutions nationwide.^26,27 Patients are characterized at baseline and are followed for AEs over the first 30 postoperative days.

Patients undergoing any of 8 common orthopedic procedures were identified in the 2012 ACS-NSQIP database using International Classification of Diseases, Ninth Revision (ICD-9) codes and Current Procedural Terminology (CPT) codes (Table 2). Any patient with missing data was excluded from this population before analysis.

First, mean SWORD was calculated and reported for patients undergoing each of the 8 procedures. Analysis of variance (ANOVA) was used to test for associations of mean SWORD with type of procedure both before and after multivariate adjustment for demographics (sex; age in years, <40, 40-49, 50-59, 60-69, 70-79, 80-89, ≥90) and comorbidities (diabetes, hypertension, chronic obstructive pulmonary disease, exertional dyspnea, end-stage renal disease, congestive heart failure).

Second, patients undergoing the procedure with the highest mean SWORD (hip fracture surgery) were examined in depth. Among only these patients, multivariate ANOVA was used to test for associations of mean SWORD with the same demographics and comorbidities.

All statistical tests were 2-tailed. Significance was set at α = 0.05 (P < .05).

All 23 institution A faculty members (100%) and 24 (89%) of the 27 institution B faculty members completed the exercise.

Total number of participants was 47, and the overall response rate was 94%. Participant characteristics are listed in Table 3.

In the ACS-NSQIP database, 85,109 patients were identified on the basis of the initial inclusion criteria.

After patients with missing data were excluded, 85,031 remained for analysis. Patient characteristics are listed in Table 4.

 

Results

Figure 1 shows mean severity weights and standard errors generated from faculty responses. Mean (standard error) severity weight for UTI was 0.23% (0.08%); blood transfusion, 0.28% (0.09%); pneumonia, 0.55% (0.15%); hospital readmission, 0.59% (0.23%); wound dehiscence, 0.64% (0.17%); deep vein thrombosis, 0.64% (0.19%); superficial SSI, 0.68% (0.23%); return to operating room, 0.91% (0.29%); progressive renal insufficiency, 0.93% (0.27%); graft/prosthesis/flap failure, 1.20% (0.34%); unplanned intubation, 1.38% (0.53%); deep SSI, 1.45% (0.38%); failure to wean from ventilator, 1.45% (0.48%); organ/space SSI, 1.76% (0.46%); sepsis without shock, 1.77% (0.42%); peripheral nerve injury, 1.83% (0.47%); pulmonary embolism, 2.99% (0.76%); acute renal failure, 3.95% (0.85%); myocardial infarction, 4.16% (0.98%); septic shock, 7.17% (1.36%); stroke, 8.73% (1.74%); cardiac arrest requiring cardiopulmonary resuscitation, 9.97% (2.46%); and coma, 15.14% (3.04%).

Among ACS-NSQIP patients, mean SWORD ranged from 0.2% (elective anterior cervical decompression and fusion) to 6.0% (hip fracture surgery) (Figure 2).

Mean SWORD was associated with procedure type both before (P < .001) and after (P < .001) controlling for demographic and comorbidity differences between populations. Among ACS-NSQIP patients having hip fracture surgery, mean SWORD was independently associated with older age, male sex, and 4 of 6 tested comorbidities (Ps < .05) (Figure 3).

Discussion

The use of national databases in studies has become increasingly common in orthopedic surgery.^1-4

However, many of these studies use composite outcomes such as “any adverse events” and “serious adverse events” to generate primary results.^5-23 Such methods implicitly consider the severity of markedly different AEs (death, UTI) to be the same. Our study provides orthopedics researchers with a tool that can be used to overcome this methodologic deficit.

The academic orthopedic surgeons who participated in our severity-weighting exercise thought the various AEs have markedly different severities. The least severe AE (UTI) was considered 0.23% as severe as postoperative death, with other events spanning the range up to 15.14% as severe as death. This wide range of severities demonstrates the problem with composite outcomes that implicitly consider all AEs similarly severe. Use of these markedly disparate weights in the development of SWORD enables this outcome to be more clinically applicable than outcomes such as “any adverse events.”

SWORD was highly associated with procedure type both before and after adjustment for demographics and comorbidities. Among patients undergoing the highest SWORD procedure (hip fracture surgery), SWORD was also associated with age, sex, and 4 of 6 tested comorbidities. Together, our findings show how SWORD is intended to be used in studies: to identify demographic, comorbidity, and procedural risk factors for an adverse postoperative course. We propose that researchers use our weighted outcome as their primary outcome—it is more meaningful than the simpler composite outcomes commonly used.

Outside orthopedic surgery, a small series of studies has addressed severity weighting of postoperative AEs.^25,28-30 However, their approach was very different, as they were not designed to generate weights that could be transferred to future studies; rather, they simply compared severities of postoperative courses for patients within each individual study. In each study, a review of each original patient record was required, as the severity of each patient’s postoperative course was characterized according to the degree of any postoperative intervention—from no intervention to minor interventions such as placement of an intravenous catheter and major interventions such as endoscopic, radiologic, and surgical procedures. Only after the degree of intervention was defined could an outcome score be assigned to a given patient. However, databases do not depict the degree of intervention with nearly enough detail for this type of approach; they typically identify only occurrence or nonoccurrence of each event. Our work, which arose independently from this body of literature, enables an entirely different type of analysis. SWORD, which is not based on degree of intervention but on perceived severity of an “average” event, enables direct application of severity weights to large databases that store simple information on occurrence and nonoccurrence of specific AEs.

This study had several limitations. Most significantly, the generated severity weights were based on the surgeons’ subjective perceptions of severity, not on definitive assessments of the impacts of specific AEs on actual patients. We did not query the specialists who treat the complications or who present data on the costs and disabilities that may arise from these AEs. In addition, to develop our severity weighting scale, we queried faculty at only 2 institutions. A survey of surgeons throughout the United States would be more representative and would minimize selection bias. This is a potential research area. Another limitation is that scoring was subjective, based on surgeons’ perceptions of patients—in contrast to the Global Burden of Disease project, in which severity was based more objectively on epidemiologic data from >150 countries.

Orthopedic database research itself has often-noted limitations, including inability to sufficiently control for confounders, potential inaccuracies in data coding, limited follow-up, and lack of orthopedic-specific outcomes.^1-4,31-33 However, this research also has much to offer, has increased tremendously over the past several years, and is expected to continue to expand. Many of the limitations of database studies cannot be entirely reversed. In providing a system for weighting postoperative AEs, our study fills a methodologic void. Future studies in orthopedics may benefit from using the severity-weighted outcome score presented here. Other fields with growth in database research may consider using similar methods to create severity-weighting systems of their own.

Am J Orthop. 2017;46(4):E235-E243. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Studies of AEs after orthopedic surgery commonly use composite AE outcomes.
• These types of outcomes treat AEs with different clinical significance similarly.
• This study created a single severity-weighted outcome that can be used to characterize the overall severity of a given patient’s postoperative course.
• Future studies may benefit from using this new severity-weighted outcome score.

Recently there has been an increase in the use of national databases for orthopedic surgery research.^1-4 Studies commonly compare rates of postoperative adverse events (AEs) across different demographic, comorbidity, and procedural characteristics.^5-23 Their conclusions often highlight different modifiable and/or nonmodifiable risk factors associated with the occurrence of postoperative events.

The several dozen AEs that have been investigated range from very severe (eg, death, myocardial infarction, coma) to less severe (eg, urinary tract infection [UTI], anemia requiring blood transfusion). A common approach for these studies is to consider many AEs together in the same analysis, asking a question such as, “What are risk factors for the occurrence of ‘adverse events’ after spine surgery?” Such studies test for associations with the occurrence of “any adverse event,” the occurrence of any “serious adverse event,” or similar composite outcomes. How common this type of study has become is indicated by the fact that in 2013 and 2014, at least 12 such studies were published in Clinical Orthopaedics and Related Research and the Journal of Bone and Joint Surgery,^5-14,21-23 and many more in other orthopedic journals.^15-20 However, there is a problem in using this type of composite outcome to perform such analyses: AEs with highly varying degrees of severity have identical impacts on the outcome variable, changing it from negative (“no adverse event”) to positive (“at least one adverse event”). As a result, the system may treat a very severe AE such as death and a very minor AE such as UTI similarly. Even in studies that use the slightly more specific composite outcome of “serious adverse events,” death and a nonlethal thromboembolic event would be treated similarly. Failure to differentiate these AEs in terms of their clinical significance detracts from the clinical applicability of conclusions drawn from studies using these types of composite AE outcomes.

In one of many examples that can be considered, a retrospective cohort study compared general and spinal anesthesia used in total knee arthroplasty.¹⁰ The rate of any AEs was higher with general anesthesia than with spinal anesthesia (12.34% vs 10.72%; P = .003). However, the only 2 specific AEs that had statistically significant differences were anemia requiring blood transfusion (6.07% vs 5.02%; P = .009) and superficial surgical-site infection (SSI; 0.92% vs 0.68%; P < .001). These 2 AEs are of relatively low severity; nevertheless, because these AEs are common, their differences constituted the majority of the difference in the rate of any AEs. In contrast, differences in the more severe AEs, such as death (0.11% vs 0.22%; P > .05), septic shock (0.14% vs 0.12%; P > .05), and myocardial infarction (0.20% vs 0.20%; P > .05), were small and not statistically significant. Had more weight been given to these more severe events, the outcome of the study likely would have been “no difference.”

To address this shortcoming in orthopedic research methodology, we created a severity-weighted outcome score that can be used to determine the overall “severity” of any given patient’s postoperative course. We also tested this novel outcome score for correlation with procedure type and patient characteristics using orthopedic patients from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP). Our intention is for database investigators to be able to use this outcome score in place of the composite outcomes that are dominating this type of research.

Methods

Generation of Severity Weights

Our method is described generally as utility weighting, assigning value weights reflective of overall impact to differing outcome states.²⁴ Parallel methods have been used to generate the disability weights used to determine disability-adjusted life years for the Global Burden of Disease project²⁵ and many other areas of health, economic, and policy research.

All orthopedic faculty members at 2 geographically disparate, large US academic institutions were invited to participate in a severity-weighting exercise. Each surgeon who agreed to participate performed the exercise independently.

Each participant was given a stack of 23 index cards, each listing the name and description of an AE monitored by ACS-NSQIP (Table 1).²⁶ In addition, in the upper right corner of each card was a box in which the participant could write a number. Each stack of cards was provided in a distinct randomized order. Written instructions for participants were exactly as follows:

• STEP 1: Please reorder the AE cards by your perception of “severity” for a patient experiencing that event after an orthopedic procedure.
• STEP 2: Once your cards are in order, please determine how many postoperative occurrences of each event you would “trade” for 1 patient experiencing postoperative death. Place this number of occurrences in the box in the upper right corner of each card.
• NOTES: As you consider each AE:
• Please consider an “average” occurrence of that AE, but note that in no case does the AE result in perioperative death.
• Please consider only the “severity” for the patient. (Do not consider the extent to which the event may be related to surgical error.)
• Please consider that the numbers you assign are relative to each other. Hence, if you would trade 20 of “event A” for 1 death, and if you would trade 40 of “event B” for 1 death, the implication is that you would trade 20 of “event A” for 40 of “event B.”
• You may readjust the order of your cards at any point.

Participants’ responses were recorded. For each number provided by each participant, the inverse (reciprocal) was taken and multiplied by 100%. This new number was taken to be the percentage severity of death that the given participant considered the given AE to embody. For example, as a hypothetical on one end of the spectrum, if a participant reported 1 (he/she would trade 1 AE X for 1 death), then the severity would be 1/1 × 100% = 100% of death, a very severe AE. Conversely, if a participant reported a very large number like 100,000 (he/she would trade 100,000 AEs X for 1 death), then the severity would be 1/100,000 × 100% = 0.001% of death, a very minor AE. More commonly, a participant will report a number like 25, which would translate to 4% of death (1/25 × 100% = 4%). For each AE, weights were then averaged across participants to derive a mean severity weight to be used to generate a novel composite outcome score.

Definition of Novel Composite Outcome Score

The novel composite outcome score would be expressed as a percentage to be interpreted as percentage severity of death, which we termed severity-weighted outcome relative to death (SWORD). For each patient, SWORD was defined as no AE (0%) or postoperative death (100%), with other AEs assigned mean severity weights based on faculty members’ survey responses. A patient with multiple AEs would be assigned the weight for the more severe AE. This method was chosen over summing the AE weights because in many cases the AEs were thought to overlap; hence, summing would be inappropriate. For example, generally a deep SSI would result in a return to the operating room, and one would not want to double-count this AE. Similarly, it would not make sense for a patient who died of a complication to have a SWORD of >100%, which would be the summing result.

Application to ACS-NSQIP Patients

ACS-NSQIP is a surgical registry that prospectively identifies patients undergoing major surgery at any of >500 institutions nationwide.^26,27 Patients are characterized at baseline and are followed for AEs over the first 30 postoperative days.

Patients undergoing any of 8 common orthopedic procedures were identified in the 2012 ACS-NSQIP database using International Classification of Diseases, Ninth Revision (ICD-9) codes and Current Procedural Terminology (CPT) codes (Table 2). Any patient with missing data was excluded from this population before analysis.

First, mean SWORD was calculated and reported for patients undergoing each of the 8 procedures. Analysis of variance (ANOVA) was used to test for associations of mean SWORD with type of procedure both before and after multivariate adjustment for demographics (sex; age in years, <40, 40-49, 50-59, 60-69, 70-79, 80-89, ≥90) and comorbidities (diabetes, hypertension, chronic obstructive pulmonary disease, exertional dyspnea, end-stage renal disease, congestive heart failure).

Second, patients undergoing the procedure with the highest mean SWORD (hip fracture surgery) were examined in depth. Among only these patients, multivariate ANOVA was used to test for associations of mean SWORD with the same demographics and comorbidities.

All statistical tests were 2-tailed. Significance was set at α = 0.05 (P < .05).

All 23 institution A faculty members (100%) and 24 (89%) of the 27 institution B faculty members completed the exercise.

Total number of participants was 47, and the overall response rate was 94%. Participant characteristics are listed in Table 3.

In the ACS-NSQIP database, 85,109 patients were identified on the basis of the initial inclusion criteria.

After patients with missing data were excluded, 85,031 remained for analysis. Patient characteristics are listed in Table 4.

 

Results

Figure 1 shows mean severity weights and standard errors generated from faculty responses. Mean (standard error) severity weight for UTI was 0.23% (0.08%); blood transfusion, 0.28% (0.09%); pneumonia, 0.55% (0.15%); hospital readmission, 0.59% (0.23%); wound dehiscence, 0.64% (0.17%); deep vein thrombosis, 0.64% (0.19%); superficial SSI, 0.68% (0.23%); return to operating room, 0.91% (0.29%); progressive renal insufficiency, 0.93% (0.27%); graft/prosthesis/flap failure, 1.20% (0.34%); unplanned intubation, 1.38% (0.53%); deep SSI, 1.45% (0.38%); failure to wean from ventilator, 1.45% (0.48%); organ/space SSI, 1.76% (0.46%); sepsis without shock, 1.77% (0.42%); peripheral nerve injury, 1.83% (0.47%); pulmonary embolism, 2.99% (0.76%); acute renal failure, 3.95% (0.85%); myocardial infarction, 4.16% (0.98%); septic shock, 7.17% (1.36%); stroke, 8.73% (1.74%); cardiac arrest requiring cardiopulmonary resuscitation, 9.97% (2.46%); and coma, 15.14% (3.04%).

Among ACS-NSQIP patients, mean SWORD ranged from 0.2% (elective anterior cervical decompression and fusion) to 6.0% (hip fracture surgery) (Figure 2).

Mean SWORD was associated with procedure type both before (P < .001) and after (P < .001) controlling for demographic and comorbidity differences between populations. Among ACS-NSQIP patients having hip fracture surgery, mean SWORD was independently associated with older age, male sex, and 4 of 6 tested comorbidities (Ps < .05) (Figure 3).

Discussion

The use of national databases in studies has become increasingly common in orthopedic surgery.^1-4

However, many of these studies use composite outcomes such as “any adverse events” and “serious adverse events” to generate primary results.^5-23 Such methods implicitly consider the severity of markedly different AEs (death, UTI) to be the same. Our study provides orthopedics researchers with a tool that can be used to overcome this methodologic deficit.

The academic orthopedic surgeons who participated in our severity-weighting exercise thought the various AEs have markedly different severities. The least severe AE (UTI) was considered 0.23% as severe as postoperative death, with other events spanning the range up to 15.14% as severe as death. This wide range of severities demonstrates the problem with composite outcomes that implicitly consider all AEs similarly severe. Use of these markedly disparate weights in the development of SWORD enables this outcome to be more clinically applicable than outcomes such as “any adverse events.”

SWORD was highly associated with procedure type both before and after adjustment for demographics and comorbidities. Among patients undergoing the highest SWORD procedure (hip fracture surgery), SWORD was also associated with age, sex, and 4 of 6 tested comorbidities. Together, our findings show how SWORD is intended to be used in studies: to identify demographic, comorbidity, and procedural risk factors for an adverse postoperative course. We propose that researchers use our weighted outcome as their primary outcome—it is more meaningful than the simpler composite outcomes commonly used.

Outside orthopedic surgery, a small series of studies has addressed severity weighting of postoperative AEs.^25,28-30 However, their approach was very different, as they were not designed to generate weights that could be transferred to future studies; rather, they simply compared severities of postoperative courses for patients within each individual study. In each study, a review of each original patient record was required, as the severity of each patient’s postoperative course was characterized according to the degree of any postoperative intervention—from no intervention to minor interventions such as placement of an intravenous catheter and major interventions such as endoscopic, radiologic, and surgical procedures. Only after the degree of intervention was defined could an outcome score be assigned to a given patient. However, databases do not depict the degree of intervention with nearly enough detail for this type of approach; they typically identify only occurrence or nonoccurrence of each event. Our work, which arose independently from this body of literature, enables an entirely different type of analysis. SWORD, which is not based on degree of intervention but on perceived severity of an “average” event, enables direct application of severity weights to large databases that store simple information on occurrence and nonoccurrence of specific AEs.

This study had several limitations. Most significantly, the generated severity weights were based on the surgeons’ subjective perceptions of severity, not on definitive assessments of the impacts of specific AEs on actual patients. We did not query the specialists who treat the complications or who present data on the costs and disabilities that may arise from these AEs. In addition, to develop our severity weighting scale, we queried faculty at only 2 institutions. A survey of surgeons throughout the United States would be more representative and would minimize selection bias. This is a potential research area. Another limitation is that scoring was subjective, based on surgeons’ perceptions of patients—in contrast to the Global Burden of Disease project, in which severity was based more objectively on epidemiologic data from >150 countries.

Orthopedic database research itself has often-noted limitations, including inability to sufficiently control for confounders, potential inaccuracies in data coding, limited follow-up, and lack of orthopedic-specific outcomes.^1-4,31-33 However, this research also has much to offer, has increased tremendously over the past several years, and is expected to continue to expand. Many of the limitations of database studies cannot be entirely reversed. In providing a system for weighting postoperative AEs, our study fills a methodologic void. Future studies in orthopedics may benefit from using the severity-weighted outcome score presented here. Other fields with growth in database research may consider using similar methods to create severity-weighting systems of their own.

Am J Orthop. 2017;46(4):E235-E243. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Studies of AEs after orthopedic surgery commonly use composite AE outcomes.
• These types of outcomes treat AEs with different clinical significance similarly.
• This study created a single severity-weighted outcome that can be used to characterize the overall severity of a given patient’s postoperative course.
• Future studies may benefit from using this new severity-weighted outcome score.

Recently there has been an increase in the use of national databases for orthopedic surgery research.^1-4 Studies commonly compare rates of postoperative adverse events (AEs) across different demographic, comorbidity, and procedural characteristics.^5-23 Their conclusions often highlight different modifiable and/or nonmodifiable risk factors associated with the occurrence of postoperative events.

The several dozen AEs that have been investigated range from very severe (eg, death, myocardial infarction, coma) to less severe (eg, urinary tract infection [UTI], anemia requiring blood transfusion). A common approach for these studies is to consider many AEs together in the same analysis, asking a question such as, “What are risk factors for the occurrence of ‘adverse events’ after spine surgery?” Such studies test for associations with the occurrence of “any adverse event,” the occurrence of any “serious adverse event,” or similar composite outcomes. How common this type of study has become is indicated by the fact that in 2013 and 2014, at least 12 such studies were published in Clinical Orthopaedics and Related Research and the Journal of Bone and Joint Surgery,^5-14,21-23 and many more in other orthopedic journals.^15-20 However, there is a problem in using this type of composite outcome to perform such analyses: AEs with highly varying degrees of severity have identical impacts on the outcome variable, changing it from negative (“no adverse event”) to positive (“at least one adverse event”). As a result, the system may treat a very severe AE such as death and a very minor AE such as UTI similarly. Even in studies that use the slightly more specific composite outcome of “serious adverse events,” death and a nonlethal thromboembolic event would be treated similarly. Failure to differentiate these AEs in terms of their clinical significance detracts from the clinical applicability of conclusions drawn from studies using these types of composite AE outcomes.

In one of many examples that can be considered, a retrospective cohort study compared general and spinal anesthesia used in total knee arthroplasty.¹⁰ The rate of any AEs was higher with general anesthesia than with spinal anesthesia (12.34% vs 10.72%; P = .003). However, the only 2 specific AEs that had statistically significant differences were anemia requiring blood transfusion (6.07% vs 5.02%; P = .009) and superficial surgical-site infection (SSI; 0.92% vs 0.68%; P < .001). These 2 AEs are of relatively low severity; nevertheless, because these AEs are common, their differences constituted the majority of the difference in the rate of any AEs. In contrast, differences in the more severe AEs, such as death (0.11% vs 0.22%; P > .05), septic shock (0.14% vs 0.12%; P > .05), and myocardial infarction (0.20% vs 0.20%; P > .05), were small and not statistically significant. Had more weight been given to these more severe events, the outcome of the study likely would have been “no difference.”

To address this shortcoming in orthopedic research methodology, we created a severity-weighted outcome score that can be used to determine the overall “severity” of any given patient’s postoperative course. We also tested this novel outcome score for correlation with procedure type and patient characteristics using orthopedic patients from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP). Our intention is for database investigators to be able to use this outcome score in place of the composite outcomes that are dominating this type of research.

Methods

Generation of Severity Weights

Our method is described generally as utility weighting, assigning value weights reflective of overall impact to differing outcome states.²⁴ Parallel methods have been used to generate the disability weights used to determine disability-adjusted life years for the Global Burden of Disease project²⁵ and many other areas of health, economic, and policy research.

All orthopedic faculty members at 2 geographically disparate, large US academic institutions were invited to participate in a severity-weighting exercise. Each surgeon who agreed to participate performed the exercise independently.

Each participant was given a stack of 23 index cards, each listing the name and description of an AE monitored by ACS-NSQIP (Table 1).²⁶ In addition, in the upper right corner of each card was a box in which the participant could write a number. Each stack of cards was provided in a distinct randomized order. Written instructions for participants were exactly as follows:

• STEP 1: Please reorder the AE cards by your perception of “severity” for a patient experiencing that event after an orthopedic procedure.
• STEP 2: Once your cards are in order, please determine how many postoperative occurrences of each event you would “trade” for 1 patient experiencing postoperative death. Place this number of occurrences in the box in the upper right corner of each card.
• NOTES: As you consider each AE:
• Please consider an “average” occurrence of that AE, but note that in no case does the AE result in perioperative death.
• Please consider only the “severity” for the patient. (Do not consider the extent to which the event may be related to surgical error.)
• Please consider that the numbers you assign are relative to each other. Hence, if you would trade 20 of “event A” for 1 death, and if you would trade 40 of “event B” for 1 death, the implication is that you would trade 20 of “event A” for 40 of “event B.”
• You may readjust the order of your cards at any point.

Participants’ responses were recorded. For each number provided by each participant, the inverse (reciprocal) was taken and multiplied by 100%. This new number was taken to be the percentage severity of death that the given participant considered the given AE to embody. For example, as a hypothetical on one end of the spectrum, if a participant reported 1 (he/she would trade 1 AE X for 1 death), then the severity would be 1/1 × 100% = 100% of death, a very severe AE. Conversely, if a participant reported a very large number like 100,000 (he/she would trade 100,000 AEs X for 1 death), then the severity would be 1/100,000 × 100% = 0.001% of death, a very minor AE. More commonly, a participant will report a number like 25, which would translate to 4% of death (1/25 × 100% = 4%). For each AE, weights were then averaged across participants to derive a mean severity weight to be used to generate a novel composite outcome score.

Definition of Novel Composite Outcome Score

The novel composite outcome score would be expressed as a percentage to be interpreted as percentage severity of death, which we termed severity-weighted outcome relative to death (SWORD). For each patient, SWORD was defined as no AE (0%) or postoperative death (100%), with other AEs assigned mean severity weights based on faculty members’ survey responses. A patient with multiple AEs would be assigned the weight for the more severe AE. This method was chosen over summing the AE weights because in many cases the AEs were thought to overlap; hence, summing would be inappropriate. For example, generally a deep SSI would result in a return to the operating room, and one would not want to double-count this AE. Similarly, it would not make sense for a patient who died of a complication to have a SWORD of >100%, which would be the summing result.

Application to ACS-NSQIP Patients

ACS-NSQIP is a surgical registry that prospectively identifies patients undergoing major surgery at any of >500 institutions nationwide.^26,27 Patients are characterized at baseline and are followed for AEs over the first 30 postoperative days.

Patients undergoing any of 8 common orthopedic procedures were identified in the 2012 ACS-NSQIP database using International Classification of Diseases, Ninth Revision (ICD-9) codes and Current Procedural Terminology (CPT) codes (Table 2). Any patient with missing data was excluded from this population before analysis.

First, mean SWORD was calculated and reported for patients undergoing each of the 8 procedures. Analysis of variance (ANOVA) was used to test for associations of mean SWORD with type of procedure both before and after multivariate adjustment for demographics (sex; age in years, <40, 40-49, 50-59, 60-69, 70-79, 80-89, ≥90) and comorbidities (diabetes, hypertension, chronic obstructive pulmonary disease, exertional dyspnea, end-stage renal disease, congestive heart failure).

Second, patients undergoing the procedure with the highest mean SWORD (hip fracture surgery) were examined in depth. Among only these patients, multivariate ANOVA was used to test for associations of mean SWORD with the same demographics and comorbidities.

All statistical tests were 2-tailed. Significance was set at α = 0.05 (P < .05).

All 23 institution A faculty members (100%) and 24 (89%) of the 27 institution B faculty members completed the exercise.

Total number of participants was 47, and the overall response rate was 94%. Participant characteristics are listed in Table 3.

In the ACS-NSQIP database, 85,109 patients were identified on the basis of the initial inclusion criteria.

After patients with missing data were excluded, 85,031 remained for analysis. Patient characteristics are listed in Table 4.

 

Results

Figure 1 shows mean severity weights and standard errors generated from faculty responses. Mean (standard error) severity weight for UTI was 0.23% (0.08%); blood transfusion, 0.28% (0.09%); pneumonia, 0.55% (0.15%); hospital readmission, 0.59% (0.23%); wound dehiscence, 0.64% (0.17%); deep vein thrombosis, 0.64% (0.19%); superficial SSI, 0.68% (0.23%); return to operating room, 0.91% (0.29%); progressive renal insufficiency, 0.93% (0.27%); graft/prosthesis/flap failure, 1.20% (0.34%); unplanned intubation, 1.38% (0.53%); deep SSI, 1.45% (0.38%); failure to wean from ventilator, 1.45% (0.48%); organ/space SSI, 1.76% (0.46%); sepsis without shock, 1.77% (0.42%); peripheral nerve injury, 1.83% (0.47%); pulmonary embolism, 2.99% (0.76%); acute renal failure, 3.95% (0.85%); myocardial infarction, 4.16% (0.98%); septic shock, 7.17% (1.36%); stroke, 8.73% (1.74%); cardiac arrest requiring cardiopulmonary resuscitation, 9.97% (2.46%); and coma, 15.14% (3.04%).

Among ACS-NSQIP patients, mean SWORD ranged from 0.2% (elective anterior cervical decompression and fusion) to 6.0% (hip fracture surgery) (Figure 2).

Mean SWORD was associated with procedure type both before (P < .001) and after (P < .001) controlling for demographic and comorbidity differences between populations. Among ACS-NSQIP patients having hip fracture surgery, mean SWORD was independently associated with older age, male sex, and 4 of 6 tested comorbidities (Ps < .05) (Figure 3).

Discussion

The use of national databases in studies has become increasingly common in orthopedic surgery.^1-4

However, many of these studies use composite outcomes such as “any adverse events” and “serious adverse events” to generate primary results.^5-23 Such methods implicitly consider the severity of markedly different AEs (death, UTI) to be the same. Our study provides orthopedics researchers with a tool that can be used to overcome this methodologic deficit.

The academic orthopedic surgeons who participated in our severity-weighting exercise thought the various AEs have markedly different severities. The least severe AE (UTI) was considered 0.23% as severe as postoperative death, with other events spanning the range up to 15.14% as severe as death. This wide range of severities demonstrates the problem with composite outcomes that implicitly consider all AEs similarly severe. Use of these markedly disparate weights in the development of SWORD enables this outcome to be more clinically applicable than outcomes such as “any adverse events.”

SWORD was highly associated with procedure type both before and after adjustment for demographics and comorbidities. Among patients undergoing the highest SWORD procedure (hip fracture surgery), SWORD was also associated with age, sex, and 4 of 6 tested comorbidities. Together, our findings show how SWORD is intended to be used in studies: to identify demographic, comorbidity, and procedural risk factors for an adverse postoperative course. We propose that researchers use our weighted outcome as their primary outcome—it is more meaningful than the simpler composite outcomes commonly used.

Outside orthopedic surgery, a small series of studies has addressed severity weighting of postoperative AEs.^25,28-30 However, their approach was very different, as they were not designed to generate weights that could be transferred to future studies; rather, they simply compared severities of postoperative courses for patients within each individual study. In each study, a review of each original patient record was required, as the severity of each patient’s postoperative course was characterized according to the degree of any postoperative intervention—from no intervention to minor interventions such as placement of an intravenous catheter and major interventions such as endoscopic, radiologic, and surgical procedures. Only after the degree of intervention was defined could an outcome score be assigned to a given patient. However, databases do not depict the degree of intervention with nearly enough detail for this type of approach; they typically identify only occurrence or nonoccurrence of each event. Our work, which arose independently from this body of literature, enables an entirely different type of analysis. SWORD, which is not based on degree of intervention but on perceived severity of an “average” event, enables direct application of severity weights to large databases that store simple information on occurrence and nonoccurrence of specific AEs.

This study had several limitations. Most significantly, the generated severity weights were based on the surgeons’ subjective perceptions of severity, not on definitive assessments of the impacts of specific AEs on actual patients. We did not query the specialists who treat the complications or who present data on the costs and disabilities that may arise from these AEs. In addition, to develop our severity weighting scale, we queried faculty at only 2 institutions. A survey of surgeons throughout the United States would be more representative and would minimize selection bias. This is a potential research area. Another limitation is that scoring was subjective, based on surgeons’ perceptions of patients—in contrast to the Global Burden of Disease project, in which severity was based more objectively on epidemiologic data from >150 countries.

Orthopedic database research itself has often-noted limitations, including inability to sufficiently control for confounders, potential inaccuracies in data coding, limited follow-up, and lack of orthopedic-specific outcomes.^1-4,31-33 However, this research also has much to offer, has increased tremendously over the past several years, and is expected to continue to expand. Many of the limitations of database studies cannot be entirely reversed. In providing a system for weighting postoperative AEs, our study fills a methodologic void. Future studies in orthopedics may benefit from using the severity-weighted outcome score presented here. Other fields with growth in database research may consider using similar methods to create severity-weighting systems of their own.

Am J Orthop. 2017;46(4):E235-E243. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

 

VIENNA – Oral antibiotic therapy is just as effective as intravenous treatment in curing bone and joint infections, but costs about $3,500 less.

Treating these infections with oral agents also “improves patient autonomy, as it’s not necessary to have IV lines at home,” and represents a generally wiser use of powerful antibiotics, Matthew Scarborough, MD, said at the European Society of Clinical Microbiology and Infectious Diseases annual congress.

Michele G Sullivan/Frontline Medical News

“The OVIVA study is really good news for our patients, for our practice in terms of antibiotic stewardship and reducing the risk of health care–associated infections, and fantastic for the health economy worldwide,” said Dr. Scarborough of Oxford (England) University.

OVIVA (Oral vs. Intravenous Antibiotics for Bone and Joint Infection) was conducted at 26 sites in the United Kingdom. It randomized 1,054 adults with bone or joint infections to 6 weeks of either oral or intravenous treatment.

An important aspect of the trial was that both oral and IV treatment choices were made before randomization, Dr. Scarborough said. However, the decisions on what drug to use were left up to the treating physician and depended on the infection site and pathogen.

The primary outcome was definite treatment failure (bacteriologic, histologic, and clinical). Patients were followed for 1 year.

Patients were a median of 60 years old. All had surgical treatment before antibiotic therapy, including debridement and, in those with implants, removal of infected devices. The lower limb was involved in 81%, including hip, knee, and foot. The infection was in an upper limb in 10% and in the spine in 7%.

Staphylococcus aureus was present in 38% of cases, coagulase-negative staphylococci in 27%, and streptococci in 15%. Gram-negative bacteria were found in 22%.

For those patients randomized to IV therapy, glycopeptides and cephalosporins were most commonly employed (41% and 33%, respectively). For oral therapy, quinolones and penicillins were most common (37% and 16%). Most patients (74%) continued antibiotic treatment for more than 6 weeks. Forty patients were lost to follow-up.

In the primary intent-to-treat analysis, the failure rate was 13% for oral therapy and 14% for IV therapy, not a significant difference. Results were similar in the other analyses, including a modified intent to treat with only patients who had complete 1-year data, and a per-protocol analysis. All of the point prevalence numbers favored oral therapy, but crossed the null. Curves in the time-to-treatment-failure analysis were virtually superimposable, as were curves in time to discontinuation of therapy.

Another subgroup analysis examined treatment failure by infective organism; again, there were no significant treatment differences in any of the pathogen subgroups examined (S. aureus, coagulase-negative staph, streptococci species, and other gram-negative bacteria).

Nor did the type of antibiotic significantly affect failure rate, Dr. Scarborough noted. The median length of stay was 14 days for patients on IV treatment and 11 days for those taking oral medications. The incidence of serious adverse events was very similar – about 86% in each group.

On a visual analog scale that assessed health-related quality of life, patients taking oral treatment reported better mobility, self-care, and activity level, and less pain, discomfort, anxiety, and depression than those taking IV medications.

Cost represented the other significant difference between the groups. Over 1 year, the mean IV treatment cost was the equivalent of $17,152, and the mean oral treatment cost was $13,611 – a significant difference of $3,541.

“This represents a potential savings to the National Health Service of 16-25 million pounds sterling ($20.6 million-$32.3 million) per year,” Dr. Scarborough said. “All coming at no expense of good clinical outcomes.”

OVIVA was sponsored by the U.K. National Institute of Health Research. Dr. Scarborough had no financial disclosures.

[email protected]

On Twitter @alz_gal

 

VIENNA – Oral antibiotic therapy is just as effective as intravenous treatment in curing bone and joint infections, but costs about $3,500 less.

Treating these infections with oral agents also “improves patient autonomy, as it’s not necessary to have IV lines at home,” and represents a generally wiser use of powerful antibiotics, Matthew Scarborough, MD, said at the European Society of Clinical Microbiology and Infectious Diseases annual congress.

Michele G Sullivan/Frontline Medical News

“The OVIVA study is really good news for our patients, for our practice in terms of antibiotic stewardship and reducing the risk of health care–associated infections, and fantastic for the health economy worldwide,” said Dr. Scarborough of Oxford (England) University.

OVIVA (Oral vs. Intravenous Antibiotics for Bone and Joint Infection) was conducted at 26 sites in the United Kingdom. It randomized 1,054 adults with bone or joint infections to 6 weeks of either oral or intravenous treatment.

An important aspect of the trial was that both oral and IV treatment choices were made before randomization, Dr. Scarborough said. However, the decisions on what drug to use were left up to the treating physician and depended on the infection site and pathogen.

The primary outcome was definite treatment failure (bacteriologic, histologic, and clinical). Patients were followed for 1 year.

Patients were a median of 60 years old. All had surgical treatment before antibiotic therapy, including debridement and, in those with implants, removal of infected devices. The lower limb was involved in 81%, including hip, knee, and foot. The infection was in an upper limb in 10% and in the spine in 7%.

Staphylococcus aureus was present in 38% of cases, coagulase-negative staphylococci in 27%, and streptococci in 15%. Gram-negative bacteria were found in 22%.

For those patients randomized to IV therapy, glycopeptides and cephalosporins were most commonly employed (41% and 33%, respectively). For oral therapy, quinolones and penicillins were most common (37% and 16%). Most patients (74%) continued antibiotic treatment for more than 6 weeks. Forty patients were lost to follow-up.

In the primary intent-to-treat analysis, the failure rate was 13% for oral therapy and 14% for IV therapy, not a significant difference. Results were similar in the other analyses, including a modified intent to treat with only patients who had complete 1-year data, and a per-protocol analysis. All of the point prevalence numbers favored oral therapy, but crossed the null. Curves in the time-to-treatment-failure analysis were virtually superimposable, as were curves in time to discontinuation of therapy.

Another subgroup analysis examined treatment failure by infective organism; again, there were no significant treatment differences in any of the pathogen subgroups examined (S. aureus, coagulase-negative staph, streptococci species, and other gram-negative bacteria).

Nor did the type of antibiotic significantly affect failure rate, Dr. Scarborough noted. The median length of stay was 14 days for patients on IV treatment and 11 days for those taking oral medications. The incidence of serious adverse events was very similar – about 86% in each group.

On a visual analog scale that assessed health-related quality of life, patients taking oral treatment reported better mobility, self-care, and activity level, and less pain, discomfort, anxiety, and depression than those taking IV medications.

Cost represented the other significant difference between the groups. Over 1 year, the mean IV treatment cost was the equivalent of $17,152, and the mean oral treatment cost was $13,611 – a significant difference of $3,541.

“This represents a potential savings to the National Health Service of 16-25 million pounds sterling ($20.6 million-$32.3 million) per year,” Dr. Scarborough said. “All coming at no expense of good clinical outcomes.”

OVIVA was sponsored by the U.K. National Institute of Health Research. Dr. Scarborough had no financial disclosures.

[email protected]

On Twitter @alz_gal

 

VIENNA – Oral antibiotic therapy is just as effective as intravenous treatment in curing bone and joint infections, but costs about $3,500 less.

Treating these infections with oral agents also “improves patient autonomy, as it’s not necessary to have IV lines at home,” and represents a generally wiser use of powerful antibiotics, Matthew Scarborough, MD, said at the European Society of Clinical Microbiology and Infectious Diseases annual congress.

Michele G Sullivan/Frontline Medical News

“The OVIVA study is really good news for our patients, for our practice in terms of antibiotic stewardship and reducing the risk of health care–associated infections, and fantastic for the health economy worldwide,” said Dr. Scarborough of Oxford (England) University.

OVIVA (Oral vs. Intravenous Antibiotics for Bone and Joint Infection) was conducted at 26 sites in the United Kingdom. It randomized 1,054 adults with bone or joint infections to 6 weeks of either oral or intravenous treatment.

An important aspect of the trial was that both oral and IV treatment choices were made before randomization, Dr. Scarborough said. However, the decisions on what drug to use were left up to the treating physician and depended on the infection site and pathogen.

The primary outcome was definite treatment failure (bacteriologic, histologic, and clinical). Patients were followed for 1 year.

Patients were a median of 60 years old. All had surgical treatment before antibiotic therapy, including debridement and, in those with implants, removal of infected devices. The lower limb was involved in 81%, including hip, knee, and foot. The infection was in an upper limb in 10% and in the spine in 7%.

Staphylococcus aureus was present in 38% of cases, coagulase-negative staphylococci in 27%, and streptococci in 15%. Gram-negative bacteria were found in 22%.

For those patients randomized to IV therapy, glycopeptides and cephalosporins were most commonly employed (41% and 33%, respectively). For oral therapy, quinolones and penicillins were most common (37% and 16%). Most patients (74%) continued antibiotic treatment for more than 6 weeks. Forty patients were lost to follow-up.

In the primary intent-to-treat analysis, the failure rate was 13% for oral therapy and 14% for IV therapy, not a significant difference. Results were similar in the other analyses, including a modified intent to treat with only patients who had complete 1-year data, and a per-protocol analysis. All of the point prevalence numbers favored oral therapy, but crossed the null. Curves in the time-to-treatment-failure analysis were virtually superimposable, as were curves in time to discontinuation of therapy.

Another subgroup analysis examined treatment failure by infective organism; again, there were no significant treatment differences in any of the pathogen subgroups examined (S. aureus, coagulase-negative staph, streptococci species, and other gram-negative bacteria).

Nor did the type of antibiotic significantly affect failure rate, Dr. Scarborough noted. The median length of stay was 14 days for patients on IV treatment and 11 days for those taking oral medications. The incidence of serious adverse events was very similar – about 86% in each group.

On a visual analog scale that assessed health-related quality of life, patients taking oral treatment reported better mobility, self-care, and activity level, and less pain, discomfort, anxiety, and depression than those taking IV medications.

Cost represented the other significant difference between the groups. Over 1 year, the mean IV treatment cost was the equivalent of $17,152, and the mean oral treatment cost was $13,611 – a significant difference of $3,541.

“This represents a potential savings to the National Health Service of 16-25 million pounds sterling ($20.6 million-$32.3 million) per year,” Dr. Scarborough said. “All coming at no expense of good clinical outcomes.”

OVIVA was sponsored by the U.K. National Institute of Health Research. Dr. Scarborough had no financial disclosures.

[email protected]

On Twitter @alz_gal

Take-Home Points

• Importance of on-field management.
• Preseason drilling of spinal injury management.
• Early and rapid intervention.
• Possible benefit of moderate systemic hypothermia as treatment for acute cervical injury.

In 2010, we reported the case of a professional American football player who sustained a complete cervical spinal cord injury (SCI) while tackling an opposing player.¹ He received prompt medical and surgical care based on then-current recommendations, but was also treated with systemic hypothermia soon after his injury. Although systemic hypothermia had been used in the management of other neurologic injuries at that time, it had not been used in humans with acute SCI, except as described in 2 case reports.^2,3 However, Dietrich⁴ described early emerging animal data on the efficacy of systemic hypothermia for acute SCI. We now provide a clinical update on our patient, who provided written informed consent for print and electronic publication of this case report.

Case Report

During a National Football League game, the player sustained a C3–C4 fracture-dislocation after a helmet-to-helmet hit on an opposing player. He fell face down on the ground and did not move. The team’s physician and trainer rushed to the player’s side, immediately assessed him, and initiated the emergency spinal resuscitation protocol.

As per protocol, the assigned team leader took charge of managing the player’s head to maintain in-line traction with the helmet in place until the head was secured in place on a backboard designed to accommodate the helmet.

In addition, 6 assistants were tasked with rolling the player to prone position with his head in traction. An equipment technician rapidly removed the player’s mask, leaving the helmet in place. The trauma ABCs (airway, breathing, circulation) were assessed. Once the airway was stable, the 6-person roll technique was used, under the team leader’s direction, to place the player on the backboard and secure him to it. Paramedics were ready to commence resuscitation, and an ambulance was driven onto the field (Figures 1-3).

Complete motor paralysis and sensory loss (American Spinal Injury Association [ASIA] level A) were noted below the clavicles during physical examination by the head athletic trainer and 2 independent physicians, and by self-report.

The patient was breathing adequately despite feeling dyspneic. He was transferred to the ambulance within 15 minutes of injury, and there he received intravenous methylprednisolone in accordance with the National Acute Spinal Cord Injury Study (NASCIS) 2 protocol (Figure 3).⁵

With the goal being to achieve relative hypothermia, chilled saline was infused intravenously, rotating ice packs were applied to the axillae and groin, the patient’s garments were removed, and the ambient temperature in the ambulance was lowered to 55°F. Repeated clinical examination in the ambulance revealed bulbocavernosus response, indicating resolution of spinal shock, though there was still no motor or sensory function below the clavicles (remained ASIA level A). During transportation, the patient was hemodynamically monitored and found to be stable, with no evidence of neurogenic shock. After 30 minutes of resuscitation, he showed slight improvement; by the time the ambulance arrived at the emergency department, crude pressure and vibratory sensation in the extremities were apparent.

On arrival at the hospital, the patient had a core temperature of 98°F, which is substantially lower than the average core temperature (≤101.7°F) of an active football player.⁶He had a normal level of consciousness and normal cranial nerve function but remained without any voluntary motor function in the extremities and still had no sensation below the clavicles, except crude pressure sensation in one hand while in the emergency department. After the helmet and shoulder pads were removed, per National Athletic Trainers’ Association (NATA) protocol⁷ (Figure 2), he was stabilized, and a hard cervical collar was placed. A lateral radiograph (Figure 4) showed a C3–C4 facet dislocation with about 46% anterior translation of C3 on C4 and obvious disruption of the facets.

Computed tomography (CT) confirmed a left C3–C4 complete facet dislocation and a right C3–C4 facet subluxation with a “perched” facet, and Digital Imaging and Communications in Medicine (DICOM) measurements showed the same canal compromise (~55%) found with magnetic resonance imaging (MRI). After CT and before MRI, repeat clinical examination revealed persistent complete motor paralysis and rudimentary sensation to deep pressure below the nipples, with proprioception indicating anterior cord syndrome. At this point, hyperreflexia and nonsustained clonus were noted. MRI showed a small right central and paracentral disk herniation superimposed on signal change within the cord as it was draped over the posterosuperior aspect of C4.

About 3 hours after injury, the patient was taken to the operating room. Although closed reduction improved alignment dramatically, it failed to completely reduce the dislocated left C3–C4 facet. An hour later, anterior C3–C4 discectomy was performed from the front with instrumented anterior interbody fusion. This was immediately followed by posterior decompressive laminectomy, bilateral facet reduction, and fusion with instrumentation. Surgery was completed within about 4 hours, almost exactly 7 hours after injury. Anesthesia records indicated a core temperature range of 94.1°F to 95.3°F with passive cooling during surgery. CT and MRI performed within 4 hours after surgery showed excellent cord decompression.

The next morning, about 14.5 hours after injury, the patient demonstrated a flicker of the adductor muscles of the lower extremities. An examination an hour later revealed 1/5 quadriceps, 2/5 adductors, and 1/5 gastrocnemius/soleus. A nurse’s hourly examinations and the surgeon’s repeat examinations revealed no other motor function. Sensory function was more difficult to evaluate because of sedation, but rudimentary sensation was noted throughout the lower extremities, and proprioception and vibratory sensation were noted as well. With passive cooling, it was difficult to consistently maintain moderate hypothermia; the patient’s core temperature ranged from 94.8°F to 98.8°F by 6:00 a.m. Therefore, the decision was made to place a Cordis sheath in the left femoral vein and introduce an intra-vena cava cooling catheter through it. This catheter was highly effective in maintaining the patient’s temperature at about 92.5°F.

Over the next 36 hours, the patient demonstrated increased motor activity in the upper and lower extremities: 1/5 biceps, 2-3/5 triceps, 3/5 quadriceps. He was slowly rewarmed and, on postoperative day 3, extubated.

Continued intravascular cooling was used for several more days to maintain normal body temperature and avoid hyperthermia. During his 12-day hospital stay, the patient showed improvement in all leg muscle groups (3-4/5 motor strength) and minimal return of upper extremity motor function (0/5 deltoids, 1/5 biceps, 3/5 triceps, 1/5 first dorsal interosseous) After discharge to a rehabilitation facility, the patient improved dramatically, but discernible deficits in sensation, strength, coordination, and endurance (ASIA level D) lasted several months, improving only slowly. A year after injury, he was ambulating independently and having normal bowel, bladder, and sexual function but residual sensory deficits in the hands and feet (glove-and-stocking distribution) and significant deficits in fine motor movement.

At 2 years, the patient underwent another anterior-only cervical procedure: The inferior adjacent segment (C4–C5) was fused because of neck pain and deformity.

Residual deficits now included only occasional tingling in fingertips and toe tips, and the patient continued to improve. Nine years after injury, he had a relapse of mechanical neck pain only and was being treated for additional adjacent segment disease.

With respect to the original injury and the evolution in cord appearance, the patient had solid arthrodesis from C3–C5 with instrumentation in good position. There was evidence of loss of lordosis at C5–C6 with disk dessication and broad-based bulging. The spinal cord had evidence of myelomalacia; this was noted when the patient was in rehabilitation, 1 month after injury. The 2-cm × 11-mm area of myelomalacia was directly posterior to the fused C3–C4 interval (original MRI, Figure 5; 2-week MRI, Figure 6).

 

Conclusion

At the time this player was injured, use of systemic hypothermia with standard therapy for acute SCI was unique and controversial. Since then, smaller randomized human studies have described the tolerable safety profile, efficacy, and potential benefits of this intervention in acute SCI in humans.^8-10 Now, modest systemic hypothermia can be one of many tools considered in the treatment of acute SCI. Before it can become the standard of care, however, additional larger prospective randomized studies need to be completed.

Am J Orthop. 2017;46(2):E79-E82. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Importance of on-field management.
• Preseason drilling of spinal injury management.
• Early and rapid intervention.
• Possible benefit of moderate systemic hypothermia as treatment for acute cervical injury.

In 2010, we reported the case of a professional American football player who sustained a complete cervical spinal cord injury (SCI) while tackling an opposing player.¹ He received prompt medical and surgical care based on then-current recommendations, but was also treated with systemic hypothermia soon after his injury. Although systemic hypothermia had been used in the management of other neurologic injuries at that time, it had not been used in humans with acute SCI, except as described in 2 case reports.^2,3 However, Dietrich⁴ described early emerging animal data on the efficacy of systemic hypothermia for acute SCI. We now provide a clinical update on our patient, who provided written informed consent for print and electronic publication of this case report.

Case Report

During a National Football League game, the player sustained a C3–C4 fracture-dislocation after a helmet-to-helmet hit on an opposing player. He fell face down on the ground and did not move. The team’s physician and trainer rushed to the player’s side, immediately assessed him, and initiated the emergency spinal resuscitation protocol.

As per protocol, the assigned team leader took charge of managing the player’s head to maintain in-line traction with the helmet in place until the head was secured in place on a backboard designed to accommodate the helmet.

In addition, 6 assistants were tasked with rolling the player to prone position with his head in traction. An equipment technician rapidly removed the player’s mask, leaving the helmet in place. The trauma ABCs (airway, breathing, circulation) were assessed. Once the airway was stable, the 6-person roll technique was used, under the team leader’s direction, to place the player on the backboard and secure him to it. Paramedics were ready to commence resuscitation, and an ambulance was driven onto the field (Figures 1-3).

Complete motor paralysis and sensory loss (American Spinal Injury Association [ASIA] level A) were noted below the clavicles during physical examination by the head athletic trainer and 2 independent physicians, and by self-report.

The patient was breathing adequately despite feeling dyspneic. He was transferred to the ambulance within 15 minutes of injury, and there he received intravenous methylprednisolone in accordance with the National Acute Spinal Cord Injury Study (NASCIS) 2 protocol (Figure 3).⁵

With the goal being to achieve relative hypothermia, chilled saline was infused intravenously, rotating ice packs were applied to the axillae and groin, the patient’s garments were removed, and the ambient temperature in the ambulance was lowered to 55°F. Repeated clinical examination in the ambulance revealed bulbocavernosus response, indicating resolution of spinal shock, though there was still no motor or sensory function below the clavicles (remained ASIA level A). During transportation, the patient was hemodynamically monitored and found to be stable, with no evidence of neurogenic shock. After 30 minutes of resuscitation, he showed slight improvement; by the time the ambulance arrived at the emergency department, crude pressure and vibratory sensation in the extremities were apparent.

On arrival at the hospital, the patient had a core temperature of 98°F, which is substantially lower than the average core temperature (≤101.7°F) of an active football player.⁶He had a normal level of consciousness and normal cranial nerve function but remained without any voluntary motor function in the extremities and still had no sensation below the clavicles, except crude pressure sensation in one hand while in the emergency department. After the helmet and shoulder pads were removed, per National Athletic Trainers’ Association (NATA) protocol⁷ (Figure 2), he was stabilized, and a hard cervical collar was placed. A lateral radiograph (Figure 4) showed a C3–C4 facet dislocation with about 46% anterior translation of C3 on C4 and obvious disruption of the facets.

Computed tomography (CT) confirmed a left C3–C4 complete facet dislocation and a right C3–C4 facet subluxation with a “perched” facet, and Digital Imaging and Communications in Medicine (DICOM) measurements showed the same canal compromise (~55%) found with magnetic resonance imaging (MRI). After CT and before MRI, repeat clinical examination revealed persistent complete motor paralysis and rudimentary sensation to deep pressure below the nipples, with proprioception indicating anterior cord syndrome. At this point, hyperreflexia and nonsustained clonus were noted. MRI showed a small right central and paracentral disk herniation superimposed on signal change within the cord as it was draped over the posterosuperior aspect of C4.

About 3 hours after injury, the patient was taken to the operating room. Although closed reduction improved alignment dramatically, it failed to completely reduce the dislocated left C3–C4 facet. An hour later, anterior C3–C4 discectomy was performed from the front with instrumented anterior interbody fusion. This was immediately followed by posterior decompressive laminectomy, bilateral facet reduction, and fusion with instrumentation. Surgery was completed within about 4 hours, almost exactly 7 hours after injury. Anesthesia records indicated a core temperature range of 94.1°F to 95.3°F with passive cooling during surgery. CT and MRI performed within 4 hours after surgery showed excellent cord decompression.

The next morning, about 14.5 hours after injury, the patient demonstrated a flicker of the adductor muscles of the lower extremities. An examination an hour later revealed 1/5 quadriceps, 2/5 adductors, and 1/5 gastrocnemius/soleus. A nurse’s hourly examinations and the surgeon’s repeat examinations revealed no other motor function. Sensory function was more difficult to evaluate because of sedation, but rudimentary sensation was noted throughout the lower extremities, and proprioception and vibratory sensation were noted as well. With passive cooling, it was difficult to consistently maintain moderate hypothermia; the patient’s core temperature ranged from 94.8°F to 98.8°F by 6:00 a.m. Therefore, the decision was made to place a Cordis sheath in the left femoral vein and introduce an intra-vena cava cooling catheter through it. This catheter was highly effective in maintaining the patient’s temperature at about 92.5°F.

Over the next 36 hours, the patient demonstrated increased motor activity in the upper and lower extremities: 1/5 biceps, 2-3/5 triceps, 3/5 quadriceps. He was slowly rewarmed and, on postoperative day 3, extubated.

Continued intravascular cooling was used for several more days to maintain normal body temperature and avoid hyperthermia. During his 12-day hospital stay, the patient showed improvement in all leg muscle groups (3-4/5 motor strength) and minimal return of upper extremity motor function (0/5 deltoids, 1/5 biceps, 3/5 triceps, 1/5 first dorsal interosseous) After discharge to a rehabilitation facility, the patient improved dramatically, but discernible deficits in sensation, strength, coordination, and endurance (ASIA level D) lasted several months, improving only slowly. A year after injury, he was ambulating independently and having normal bowel, bladder, and sexual function but residual sensory deficits in the hands and feet (glove-and-stocking distribution) and significant deficits in fine motor movement.

At 2 years, the patient underwent another anterior-only cervical procedure: The inferior adjacent segment (C4–C5) was fused because of neck pain and deformity.

Residual deficits now included only occasional tingling in fingertips and toe tips, and the patient continued to improve. Nine years after injury, he had a relapse of mechanical neck pain only and was being treated for additional adjacent segment disease.

With respect to the original injury and the evolution in cord appearance, the patient had solid arthrodesis from C3–C5 with instrumentation in good position. There was evidence of loss of lordosis at C5–C6 with disk dessication and broad-based bulging. The spinal cord had evidence of myelomalacia; this was noted when the patient was in rehabilitation, 1 month after injury. The 2-cm × 11-mm area of myelomalacia was directly posterior to the fused C3–C4 interval (original MRI, Figure 5; 2-week MRI, Figure 6).

 

Conclusion

At the time this player was injured, use of systemic hypothermia with standard therapy for acute SCI was unique and controversial. Since then, smaller randomized human studies have described the tolerable safety profile, efficacy, and potential benefits of this intervention in acute SCI in humans.^8-10 Now, modest systemic hypothermia can be one of many tools considered in the treatment of acute SCI. Before it can become the standard of care, however, additional larger prospective randomized studies need to be completed.

Am J Orthop. 2017;46(2):E79-E82. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Importance of on-field management.
• Preseason drilling of spinal injury management.
• Early and rapid intervention.
• Possible benefit of moderate systemic hypothermia as treatment for acute cervical injury.

In 2010, we reported the case of a professional American football player who sustained a complete cervical spinal cord injury (SCI) while tackling an opposing player.¹ He received prompt medical and surgical care based on then-current recommendations, but was also treated with systemic hypothermia soon after his injury. Although systemic hypothermia had been used in the management of other neurologic injuries at that time, it had not been used in humans with acute SCI, except as described in 2 case reports.^2,3 However, Dietrich⁴ described early emerging animal data on the efficacy of systemic hypothermia for acute SCI. We now provide a clinical update on our patient, who provided written informed consent for print and electronic publication of this case report.

Case Report

During a National Football League game, the player sustained a C3–C4 fracture-dislocation after a helmet-to-helmet hit on an opposing player. He fell face down on the ground and did not move. The team’s physician and trainer rushed to the player’s side, immediately assessed him, and initiated the emergency spinal resuscitation protocol.

As per protocol, the assigned team leader took charge of managing the player’s head to maintain in-line traction with the helmet in place until the head was secured in place on a backboard designed to accommodate the helmet.

In addition, 6 assistants were tasked with rolling the player to prone position with his head in traction. An equipment technician rapidly removed the player’s mask, leaving the helmet in place. The trauma ABCs (airway, breathing, circulation) were assessed. Once the airway was stable, the 6-person roll technique was used, under the team leader’s direction, to place the player on the backboard and secure him to it. Paramedics were ready to commence resuscitation, and an ambulance was driven onto the field (Figures 1-3).

Complete motor paralysis and sensory loss (American Spinal Injury Association [ASIA] level A) were noted below the clavicles during physical examination by the head athletic trainer and 2 independent physicians, and by self-report.

The patient was breathing adequately despite feeling dyspneic. He was transferred to the ambulance within 15 minutes of injury, and there he received intravenous methylprednisolone in accordance with the National Acute Spinal Cord Injury Study (NASCIS) 2 protocol (Figure 3).⁵

With the goal being to achieve relative hypothermia, chilled saline was infused intravenously, rotating ice packs were applied to the axillae and groin, the patient’s garments were removed, and the ambient temperature in the ambulance was lowered to 55°F. Repeated clinical examination in the ambulance revealed bulbocavernosus response, indicating resolution of spinal shock, though there was still no motor or sensory function below the clavicles (remained ASIA level A). During transportation, the patient was hemodynamically monitored and found to be stable, with no evidence of neurogenic shock. After 30 minutes of resuscitation, he showed slight improvement; by the time the ambulance arrived at the emergency department, crude pressure and vibratory sensation in the extremities were apparent.

On arrival at the hospital, the patient had a core temperature of 98°F, which is substantially lower than the average core temperature (≤101.7°F) of an active football player.⁶He had a normal level of consciousness and normal cranial nerve function but remained without any voluntary motor function in the extremities and still had no sensation below the clavicles, except crude pressure sensation in one hand while in the emergency department. After the helmet and shoulder pads were removed, per National Athletic Trainers’ Association (NATA) protocol⁷ (Figure 2), he was stabilized, and a hard cervical collar was placed. A lateral radiograph (Figure 4) showed a C3–C4 facet dislocation with about 46% anterior translation of C3 on C4 and obvious disruption of the facets.

Computed tomography (CT) confirmed a left C3–C4 complete facet dislocation and a right C3–C4 facet subluxation with a “perched” facet, and Digital Imaging and Communications in Medicine (DICOM) measurements showed the same canal compromise (~55%) found with magnetic resonance imaging (MRI). After CT and before MRI, repeat clinical examination revealed persistent complete motor paralysis and rudimentary sensation to deep pressure below the nipples, with proprioception indicating anterior cord syndrome. At this point, hyperreflexia and nonsustained clonus were noted. MRI showed a small right central and paracentral disk herniation superimposed on signal change within the cord as it was draped over the posterosuperior aspect of C4.

About 3 hours after injury, the patient was taken to the operating room. Although closed reduction improved alignment dramatically, it failed to completely reduce the dislocated left C3–C4 facet. An hour later, anterior C3–C4 discectomy was performed from the front with instrumented anterior interbody fusion. This was immediately followed by posterior decompressive laminectomy, bilateral facet reduction, and fusion with instrumentation. Surgery was completed within about 4 hours, almost exactly 7 hours after injury. Anesthesia records indicated a core temperature range of 94.1°F to 95.3°F with passive cooling during surgery. CT and MRI performed within 4 hours after surgery showed excellent cord decompression.

The next morning, about 14.5 hours after injury, the patient demonstrated a flicker of the adductor muscles of the lower extremities. An examination an hour later revealed 1/5 quadriceps, 2/5 adductors, and 1/5 gastrocnemius/soleus. A nurse’s hourly examinations and the surgeon’s repeat examinations revealed no other motor function. Sensory function was more difficult to evaluate because of sedation, but rudimentary sensation was noted throughout the lower extremities, and proprioception and vibratory sensation were noted as well. With passive cooling, it was difficult to consistently maintain moderate hypothermia; the patient’s core temperature ranged from 94.8°F to 98.8°F by 6:00 a.m. Therefore, the decision was made to place a Cordis sheath in the left femoral vein and introduce an intra-vena cava cooling catheter through it. This catheter was highly effective in maintaining the patient’s temperature at about 92.5°F.

Over the next 36 hours, the patient demonstrated increased motor activity in the upper and lower extremities: 1/5 biceps, 2-3/5 triceps, 3/5 quadriceps. He was slowly rewarmed and, on postoperative day 3, extubated.

Continued intravascular cooling was used for several more days to maintain normal body temperature and avoid hyperthermia. During his 12-day hospital stay, the patient showed improvement in all leg muscle groups (3-4/5 motor strength) and minimal return of upper extremity motor function (0/5 deltoids, 1/5 biceps, 3/5 triceps, 1/5 first dorsal interosseous) After discharge to a rehabilitation facility, the patient improved dramatically, but discernible deficits in sensation, strength, coordination, and endurance (ASIA level D) lasted several months, improving only slowly. A year after injury, he was ambulating independently and having normal bowel, bladder, and sexual function but residual sensory deficits in the hands and feet (glove-and-stocking distribution) and significant deficits in fine motor movement.

At 2 years, the patient underwent another anterior-only cervical procedure: The inferior adjacent segment (C4–C5) was fused because of neck pain and deformity.

Residual deficits now included only occasional tingling in fingertips and toe tips, and the patient continued to improve. Nine years after injury, he had a relapse of mechanical neck pain only and was being treated for additional adjacent segment disease.

With respect to the original injury and the evolution in cord appearance, the patient had solid arthrodesis from C3–C5 with instrumentation in good position. There was evidence of loss of lordosis at C5–C6 with disk dessication and broad-based bulging. The spinal cord had evidence of myelomalacia; this was noted when the patient was in rehabilitation, 1 month after injury. The 2-cm × 11-mm area of myelomalacia was directly posterior to the fused C3–C4 interval (original MRI, Figure 5; 2-week MRI, Figure 6).

 

Conclusion

At the time this player was injured, use of systemic hypothermia with standard therapy for acute SCI was unique and controversial. Since then, smaller randomized human studies have described the tolerable safety profile, efficacy, and potential benefits of this intervention in acute SCI in humans.^8-10 Now, modest systemic hypothermia can be one of many tools considered in the treatment of acute SCI. Before it can become the standard of care, however, additional larger prospective randomized studies need to be completed.

Am J Orthop. 2017;46(2):E79-E82. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Adolescent growth spurt, height-to-weight ratio, and perioperative weight loss are risk factors associated with SMA syndrome following pediatric spine surgery.
• Must recognize nonspecific symptoms such as abdominal pain, tenderness, distention, bilious or projectile vomiting, hypoactive bowel sounds, and anorexia postoperatively.
• Complications of SMA syndrome can potentially lead to aspiration pneumonia, acute gastric rupture, or cardiovascular collapse and death.

Superior mesenteric artery (SMA) syndrome resulting from surgical treatment of scoliosis has been recognized in the medical literature since 1752.¹ Throughout the literature, SMA syndrome variably has been referred to as cast syndrome, Wilkie syndrome, arteriomesenteric duodenal obstruction, and chronic duodenal ileus.² We now recognize numerous etiologies of SMA syndrome, as several sources can externally compress the duodenum. Classic acute symptoms of bowel obstruction include bilious vomiting, nausea, and epigastric pain. Chronic manifestations of SMA syndrome may include weight loss and decreased appetite. Our literature review revealed that adolescent growth spurt, height-to-weight ratio, and perioperative weight loss are risk factors associated with SMA syndrome after pediatric spine surgery.

We report the case of a 14-year-old boy who developed SMA syndrome after undergoing scoliosis surgery. The patient and his mother provided written informed consent for print and electronic publication of this case report.

Case Report

A 14-year-old boy with a history of idiopathic scoliosis presented to Cohen Children’s Hospital (Long Island Jewish Medical Center) with bilious vomiting that had persisted for 7 days after posterior T9–L4 fusion with instrumentation.

Preoperative radiographs revealed a 55° right Lenke V C curve (Figures 1, 2). Before the procedure, the patient weighed 111.6 lb and was 175 cm tall. The surgery was uneventful, with a curve correction to about 7° (Figures 3A, 3B). No abnormalities were noted during intraoperative neurologic monitoring. After an unremarkable postoperative course, on postoperative day 19 the patient presented to the emergency department (ED) with abdominal pain, nausea, and vomiting of 3 days’ duration. Right lower quadrant ultrasound revealed nonspecific fluid-filled bowel loops, and the patient was discharged with antiemetics and instructions for hydration.

Two days later, he returned to the ED with unrelenting brown vomitus and abdominal pain and noted a 20-lb weight loss over 2 weeks. He was admitted to the postanesthesia care unit for dehydration and for QT prolongation secondary to electrolyte abnormalities. On admission, he weighed 88.2 lb. An upper gastrointestinal (GI) contrast radiograph confirmed a diagnosis of SMA syndrome, and a nasojejunal tube was placed. The patient gained no weight over 10 days; a gastrojejunal tube was placed until he was able to tolerate oral nutritional intake, 5 weeks later. He was followed by the nutrition and general surgery teams to ensure clinical improvement.

Surgical intervention was unnecessary. One year after surgery, the patient was home and doing well without permanent sequelae.

Discussion

SMA syndrome is attributed to the anatomical orientation of the third part of the duodenum, which passes between the aorta and the SMA (Figure 4).

The SMA, an anterior branch of the aorta at the L1 vertebral level, is encased in fat and lymphatic tissue. Its acute caudal descent is sometimes referred to as a nutcracker configuration.² Normal SMA angles are highly variable. One study described 75 aortas with angles ranging from 20° to 70°.³ SMA angle reduction results in extrinsic compression of the duodenum by the SMA. A common influence is the loss of protective peripancreatic and periduodenal fat below the SMA origin secondary to significant weight loss of any kind, such as from anorexia nervosa, malabsorption, and malignancy. Correcting a scoliotic curve through spinal manipulation essentially results in a lengthening of the vertebral column, which displaces the SMA origin more superiorly and creates a more acute aortomesenteric artery angle.

Adolescents are particularly vulnerable to this condition. Faster adolescent bone growth relative to visceral growth is accompanied by a decrease in SMA angle.³ Occasionally, body casts are used after surgery to immobilize the vertebrae and augment healing. Cast syndrome occurs when pressure from a body cast causes a bowel obstruction secondary to spinal hyperextension and amplified spinal lordosis.² This finding, dating to the 19th century, was reported by Willet⁴ when a patient died 48 hours after application of a body cast. In 1950, the term cast syndrome was coined after a motorcyclist’s injuries were treated with a hip spica cast and the patient died of cardiovascular collapse secondary to persistent vomiting.⁵

Table 1 summarizes various evaluation, diagnosis, and treatment algorithms designed to optimize nutrition and weight in patients developing signs and symptoms of SMA syndrome after posterior spinal instrumentation and fusion for adolescent idiopathic scoliosis (AIS).

Of note, about 50% of patients with SMA syndrome present in the first week after spine surgery, 35% in the second week, and 15% more than 2 weeks after surgery. A patient presenting with abdominal pain/distension, nausea, and vomiting after scoliosis surgery should be initially evaluated for signs of intestinal obstruction.⁶ An abdominal radiograph can be used to assess for distended bowel gas or air-fluid levels, though this imaging study has also been found to be within normal range in an eventual SMA syndrome diagnosis. SMA syndrome can often be differentiated from postoperative ileus by fever/tachycardia and peritoneal signs. In the presence of positive findings for intestinal obstruction, initial management should begin with nasogastric decompression, electrolyte correction, and intravenous hydration. Otherwise, management should be to observe, treat with antiemetics, and reassess periodically.⁶ The first step is to start auxiliary enteral nutritional support through a nasojejunal feeding tube—or total parenteral nutrition if enteral feeding is unacceptable. Often, SMA syndrome is definitively diagnosed with an upper GI barium study with simultaneous angiography. If the diagnosis of SMA syndrome is made and symptoms improve, conservative management should be continued and diet slowly advanced. If symptoms worsen or significant weight loss occurs, surgical management should be considered. Surgical management is performed through laparoscopic or open duodenojejunostomy, division of the ligament of Treitz, or a modified Ladd procedure.^7-10 Removal of spinal implants and cast is unnecessary, except when lumbar spine hyperextension is the cause, in which case cast and metal implants must be removed to relieve the duodenum from the SMA.⁷The incidence of SMA syndrome after scoliosis surgery is 1% to 4.7%.^3,6,7 Our literature review of SMA syndrome after scoliosis surgery for AIS revealed 19 case reports over 45 years (Table 2).

Studies reported that the incidence of SMA syndrome was higher in certain groups based on the extent of spinal deformity and the Lenke classification system for scoliosis.^11,12 Specifically, groups with body mass index under the 25th percentile, Lenke B or C (laterally displaced, curved) scoliosis, and stiffer thoracic curves (<60% correction) have a higher incidence.¹² Overall, initial presentation of SMA syndrome generally consists of a combination of abdominal pain/distension, nausea, vomiting, and varying degrees of weight loss. Although the predominant cases are confirmed with upper GI contrast studies, some cases are confirmed with radiographs, laboratory (serum lipase) abnormalities, and correlated with their clinical presentation in order to direct their therapy.^13-15 For patients diagnosed with SMA syndrome, length of stay varies significantly, from 3 to 71 days. Time in hospital generally depends on ability to transition a patient to oral intake without complication. Eighty-five percent of reported cases of SMA syndrome after spinal surgery for AIS present within the first 2 weeks after surgery.^{1,6,7,9,13-19}Our patient’s case had a combination of unique features. First, he presented 19 days (almost 3 weeks) after surgery. We identified only 3 other case reports in which the patient presented later (most SMA syndrome symptoms present within 2 weeks of the spinal procedure). One patient presented on postoperative day 27 and was discharged with a nasojejunal tube because of an inability to tolerate oral intake.⁶ Another patient presented 40 days after surgery, underwent laparotomy (a fundal perforation was found), and died immediately afterward.¹⁵ A third presented 45 days after surgery and had a treatment experience similar to our patient’s: nasogastric decompression, intravenous fluids, nasojejunal tube feeding, and transition to oral intake before discharge.⁷Our case’s second unique feature is the 20-lb weight loss over 2 weeks—more than in most other cases over the same period. For patients with recorded weight loss, average weight loss was about 6.2 pounds per postoperative presentation week, and only 1 patient presented with a steeper trajectory of weight loss before presentation.¹⁸ Our patient may have waited longer to present to the ED or may have had a more severe case of the disease.

The third unique feature in this case is electrocardiogram findings. Although some cases briefly discussed electrolyte abnormalities, none presented evidence that these abnormalities caused cardiac changes.^6,16,18 The overall clinical significance of the QT prolongation in our patient’s case is unknown, as this finding was improved with correction of the electrolyte abnormalities and appropriate fluid replenishment.

Early recognition of nonspecific symptoms (eg, abdominal pain, tenderness, distension, bilious or projectile vomiting, hypoactive bowel sounds, anorexia) plays a key role in preventing severe morbidity and mortality from SMA syndrome after scoliosis surgery. Although many patients present in the semiclassic obstructed pattern, notable reasons for diagnostic delay include normal appetite and bowel sounds.³ For example, SMA syndrome may be misdiagnosed as stomach flu because of unfamiliarity with disease diagnosis and management.²⁰ Complications of SMA syndrome can potentially lead to aspiration pneumonia, acute gastric rupture, and cardiovascular collapse and death.

Am J Orthop. 2017;46(2):E124-E130. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Adolescent growth spurt, height-to-weight ratio, and perioperative weight loss are risk factors associated with SMA syndrome following pediatric spine surgery.
• Must recognize nonspecific symptoms such as abdominal pain, tenderness, distention, bilious or projectile vomiting, hypoactive bowel sounds, and anorexia postoperatively.
• Complications of SMA syndrome can potentially lead to aspiration pneumonia, acute gastric rupture, or cardiovascular collapse and death.

Superior mesenteric artery (SMA) syndrome resulting from surgical treatment of scoliosis has been recognized in the medical literature since 1752.¹ Throughout the literature, SMA syndrome variably has been referred to as cast syndrome, Wilkie syndrome, arteriomesenteric duodenal obstruction, and chronic duodenal ileus.² We now recognize numerous etiologies of SMA syndrome, as several sources can externally compress the duodenum. Classic acute symptoms of bowel obstruction include bilious vomiting, nausea, and epigastric pain. Chronic manifestations of SMA syndrome may include weight loss and decreased appetite. Our literature review revealed that adolescent growth spurt, height-to-weight ratio, and perioperative weight loss are risk factors associated with SMA syndrome after pediatric spine surgery.

We report the case of a 14-year-old boy who developed SMA syndrome after undergoing scoliosis surgery. The patient and his mother provided written informed consent for print and electronic publication of this case report.

Case Report

A 14-year-old boy with a history of idiopathic scoliosis presented to Cohen Children’s Hospital (Long Island Jewish Medical Center) with bilious vomiting that had persisted for 7 days after posterior T9–L4 fusion with instrumentation.

Preoperative radiographs revealed a 55° right Lenke V C curve (Figures 1, 2). Before the procedure, the patient weighed 111.6 lb and was 175 cm tall. The surgery was uneventful, with a curve correction to about 7° (Figures 3A, 3B). No abnormalities were noted during intraoperative neurologic monitoring. After an unremarkable postoperative course, on postoperative day 19 the patient presented to the emergency department (ED) with abdominal pain, nausea, and vomiting of 3 days’ duration. Right lower quadrant ultrasound revealed nonspecific fluid-filled bowel loops, and the patient was discharged with antiemetics and instructions for hydration.

Two days later, he returned to the ED with unrelenting brown vomitus and abdominal pain and noted a 20-lb weight loss over 2 weeks. He was admitted to the postanesthesia care unit for dehydration and for QT prolongation secondary to electrolyte abnormalities. On admission, he weighed 88.2 lb. An upper gastrointestinal (GI) contrast radiograph confirmed a diagnosis of SMA syndrome, and a nasojejunal tube was placed. The patient gained no weight over 10 days; a gastrojejunal tube was placed until he was able to tolerate oral nutritional intake, 5 weeks later. He was followed by the nutrition and general surgery teams to ensure clinical improvement.

Surgical intervention was unnecessary. One year after surgery, the patient was home and doing well without permanent sequelae.

Discussion

SMA syndrome is attributed to the anatomical orientation of the third part of the duodenum, which passes between the aorta and the SMA (Figure 4).

The SMA, an anterior branch of the aorta at the L1 vertebral level, is encased in fat and lymphatic tissue. Its acute caudal descent is sometimes referred to as a nutcracker configuration.² Normal SMA angles are highly variable. One study described 75 aortas with angles ranging from 20° to 70°.³ SMA angle reduction results in extrinsic compression of the duodenum by the SMA. A common influence is the loss of protective peripancreatic and periduodenal fat below the SMA origin secondary to significant weight loss of any kind, such as from anorexia nervosa, malabsorption, and malignancy. Correcting a scoliotic curve through spinal manipulation essentially results in a lengthening of the vertebral column, which displaces the SMA origin more superiorly and creates a more acute aortomesenteric artery angle.

Adolescents are particularly vulnerable to this condition. Faster adolescent bone growth relative to visceral growth is accompanied by a decrease in SMA angle.³ Occasionally, body casts are used after surgery to immobilize the vertebrae and augment healing. Cast syndrome occurs when pressure from a body cast causes a bowel obstruction secondary to spinal hyperextension and amplified spinal lordosis.² This finding, dating to the 19th century, was reported by Willet⁴ when a patient died 48 hours after application of a body cast. In 1950, the term cast syndrome was coined after a motorcyclist’s injuries were treated with a hip spica cast and the patient died of cardiovascular collapse secondary to persistent vomiting.⁵

Table 1 summarizes various evaluation, diagnosis, and treatment algorithms designed to optimize nutrition and weight in patients developing signs and symptoms of SMA syndrome after posterior spinal instrumentation and fusion for adolescent idiopathic scoliosis (AIS).

Of note, about 50% of patients with SMA syndrome present in the first week after spine surgery, 35% in the second week, and 15% more than 2 weeks after surgery. A patient presenting with abdominal pain/distension, nausea, and vomiting after scoliosis surgery should be initially evaluated for signs of intestinal obstruction.⁶ An abdominal radiograph can be used to assess for distended bowel gas or air-fluid levels, though this imaging study has also been found to be within normal range in an eventual SMA syndrome diagnosis. SMA syndrome can often be differentiated from postoperative ileus by fever/tachycardia and peritoneal signs. In the presence of positive findings for intestinal obstruction, initial management should begin with nasogastric decompression, electrolyte correction, and intravenous hydration. Otherwise, management should be to observe, treat with antiemetics, and reassess periodically.⁶ The first step is to start auxiliary enteral nutritional support through a nasojejunal feeding tube—or total parenteral nutrition if enteral feeding is unacceptable. Often, SMA syndrome is definitively diagnosed with an upper GI barium study with simultaneous angiography. If the diagnosis of SMA syndrome is made and symptoms improve, conservative management should be continued and diet slowly advanced. If symptoms worsen or significant weight loss occurs, surgical management should be considered. Surgical management is performed through laparoscopic or open duodenojejunostomy, division of the ligament of Treitz, or a modified Ladd procedure.^7-10 Removal of spinal implants and cast is unnecessary, except when lumbar spine hyperextension is the cause, in which case cast and metal implants must be removed to relieve the duodenum from the SMA.⁷The incidence of SMA syndrome after scoliosis surgery is 1% to 4.7%.^3,6,7 Our literature review of SMA syndrome after scoliosis surgery for AIS revealed 19 case reports over 45 years (Table 2).

Studies reported that the incidence of SMA syndrome was higher in certain groups based on the extent of spinal deformity and the Lenke classification system for scoliosis.^11,12 Specifically, groups with body mass index under the 25th percentile, Lenke B or C (laterally displaced, curved) scoliosis, and stiffer thoracic curves (<60% correction) have a higher incidence.¹² Overall, initial presentation of SMA syndrome generally consists of a combination of abdominal pain/distension, nausea, vomiting, and varying degrees of weight loss. Although the predominant cases are confirmed with upper GI contrast studies, some cases are confirmed with radiographs, laboratory (serum lipase) abnormalities, and correlated with their clinical presentation in order to direct their therapy.^13-15 For patients diagnosed with SMA syndrome, length of stay varies significantly, from 3 to 71 days. Time in hospital generally depends on ability to transition a patient to oral intake without complication. Eighty-five percent of reported cases of SMA syndrome after spinal surgery for AIS present within the first 2 weeks after surgery.^{1,6,7,9,13-19}Our patient’s case had a combination of unique features. First, he presented 19 days (almost 3 weeks) after surgery. We identified only 3 other case reports in which the patient presented later (most SMA syndrome symptoms present within 2 weeks of the spinal procedure). One patient presented on postoperative day 27 and was discharged with a nasojejunal tube because of an inability to tolerate oral intake.⁶ Another patient presented 40 days after surgery, underwent laparotomy (a fundal perforation was found), and died immediately afterward.¹⁵ A third presented 45 days after surgery and had a treatment experience similar to our patient’s: nasogastric decompression, intravenous fluids, nasojejunal tube feeding, and transition to oral intake before discharge.⁷Our case’s second unique feature is the 20-lb weight loss over 2 weeks—more than in most other cases over the same period. For patients with recorded weight loss, average weight loss was about 6.2 pounds per postoperative presentation week, and only 1 patient presented with a steeper trajectory of weight loss before presentation.¹⁸ Our patient may have waited longer to present to the ED or may have had a more severe case of the disease.

The third unique feature in this case is electrocardiogram findings. Although some cases briefly discussed electrolyte abnormalities, none presented evidence that these abnormalities caused cardiac changes.^6,16,18 The overall clinical significance of the QT prolongation in our patient’s case is unknown, as this finding was improved with correction of the electrolyte abnormalities and appropriate fluid replenishment.

Early recognition of nonspecific symptoms (eg, abdominal pain, tenderness, distension, bilious or projectile vomiting, hypoactive bowel sounds, anorexia) plays a key role in preventing severe morbidity and mortality from SMA syndrome after scoliosis surgery. Although many patients present in the semiclassic obstructed pattern, notable reasons for diagnostic delay include normal appetite and bowel sounds.³ For example, SMA syndrome may be misdiagnosed as stomach flu because of unfamiliarity with disease diagnosis and management.²⁰ Complications of SMA syndrome can potentially lead to aspiration pneumonia, acute gastric rupture, and cardiovascular collapse and death.

Am J Orthop. 2017;46(2):E124-E130. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Adolescent growth spurt, height-to-weight ratio, and perioperative weight loss are risk factors associated with SMA syndrome following pediatric spine surgery.
• Must recognize nonspecific symptoms such as abdominal pain, tenderness, distention, bilious or projectile vomiting, hypoactive bowel sounds, and anorexia postoperatively.
• Complications of SMA syndrome can potentially lead to aspiration pneumonia, acute gastric rupture, or cardiovascular collapse and death.

Superior mesenteric artery (SMA) syndrome resulting from surgical treatment of scoliosis has been recognized in the medical literature since 1752.¹ Throughout the literature, SMA syndrome variably has been referred to as cast syndrome, Wilkie syndrome, arteriomesenteric duodenal obstruction, and chronic duodenal ileus.² We now recognize numerous etiologies of SMA syndrome, as several sources can externally compress the duodenum. Classic acute symptoms of bowel obstruction include bilious vomiting, nausea, and epigastric pain. Chronic manifestations of SMA syndrome may include weight loss and decreased appetite. Our literature review revealed that adolescent growth spurt, height-to-weight ratio, and perioperative weight loss are risk factors associated with SMA syndrome after pediatric spine surgery.

We report the case of a 14-year-old boy who developed SMA syndrome after undergoing scoliosis surgery. The patient and his mother provided written informed consent for print and electronic publication of this case report.

Case Report

A 14-year-old boy with a history of idiopathic scoliosis presented to Cohen Children’s Hospital (Long Island Jewish Medical Center) with bilious vomiting that had persisted for 7 days after posterior T9–L4 fusion with instrumentation.

Preoperative radiographs revealed a 55° right Lenke V C curve (Figures 1, 2). Before the procedure, the patient weighed 111.6 lb and was 175 cm tall. The surgery was uneventful, with a curve correction to about 7° (Figures 3A, 3B). No abnormalities were noted during intraoperative neurologic monitoring. After an unremarkable postoperative course, on postoperative day 19 the patient presented to the emergency department (ED) with abdominal pain, nausea, and vomiting of 3 days’ duration. Right lower quadrant ultrasound revealed nonspecific fluid-filled bowel loops, and the patient was discharged with antiemetics and instructions for hydration.

Two days later, he returned to the ED with unrelenting brown vomitus and abdominal pain and noted a 20-lb weight loss over 2 weeks. He was admitted to the postanesthesia care unit for dehydration and for QT prolongation secondary to electrolyte abnormalities. On admission, he weighed 88.2 lb. An upper gastrointestinal (GI) contrast radiograph confirmed a diagnosis of SMA syndrome, and a nasojejunal tube was placed. The patient gained no weight over 10 days; a gastrojejunal tube was placed until he was able to tolerate oral nutritional intake, 5 weeks later. He was followed by the nutrition and general surgery teams to ensure clinical improvement.

Surgical intervention was unnecessary. One year after surgery, the patient was home and doing well without permanent sequelae.

Discussion

SMA syndrome is attributed to the anatomical orientation of the third part of the duodenum, which passes between the aorta and the SMA (Figure 4).

The SMA, an anterior branch of the aorta at the L1 vertebral level, is encased in fat and lymphatic tissue. Its acute caudal descent is sometimes referred to as a nutcracker configuration.² Normal SMA angles are highly variable. One study described 75 aortas with angles ranging from 20° to 70°.³ SMA angle reduction results in extrinsic compression of the duodenum by the SMA. A common influence is the loss of protective peripancreatic and periduodenal fat below the SMA origin secondary to significant weight loss of any kind, such as from anorexia nervosa, malabsorption, and malignancy. Correcting a scoliotic curve through spinal manipulation essentially results in a lengthening of the vertebral column, which displaces the SMA origin more superiorly and creates a more acute aortomesenteric artery angle.

Adolescents are particularly vulnerable to this condition. Faster adolescent bone growth relative to visceral growth is accompanied by a decrease in SMA angle.³ Occasionally, body casts are used after surgery to immobilize the vertebrae and augment healing. Cast syndrome occurs when pressure from a body cast causes a bowel obstruction secondary to spinal hyperextension and amplified spinal lordosis.² This finding, dating to the 19th century, was reported by Willet⁴ when a patient died 48 hours after application of a body cast. In 1950, the term cast syndrome was coined after a motorcyclist’s injuries were treated with a hip spica cast and the patient died of cardiovascular collapse secondary to persistent vomiting.⁵

Table 1 summarizes various evaluation, diagnosis, and treatment algorithms designed to optimize nutrition and weight in patients developing signs and symptoms of SMA syndrome after posterior spinal instrumentation and fusion for adolescent idiopathic scoliosis (AIS).

Of note, about 50% of patients with SMA syndrome present in the first week after spine surgery, 35% in the second week, and 15% more than 2 weeks after surgery. A patient presenting with abdominal pain/distension, nausea, and vomiting after scoliosis surgery should be initially evaluated for signs of intestinal obstruction.⁶ An abdominal radiograph can be used to assess for distended bowel gas or air-fluid levels, though this imaging study has also been found to be within normal range in an eventual SMA syndrome diagnosis. SMA syndrome can often be differentiated from postoperative ileus by fever/tachycardia and peritoneal signs. In the presence of positive findings for intestinal obstruction, initial management should begin with nasogastric decompression, electrolyte correction, and intravenous hydration. Otherwise, management should be to observe, treat with antiemetics, and reassess periodically.⁶ The first step is to start auxiliary enteral nutritional support through a nasojejunal feeding tube—or total parenteral nutrition if enteral feeding is unacceptable. Often, SMA syndrome is definitively diagnosed with an upper GI barium study with simultaneous angiography. If the diagnosis of SMA syndrome is made and symptoms improve, conservative management should be continued and diet slowly advanced. If symptoms worsen or significant weight loss occurs, surgical management should be considered. Surgical management is performed through laparoscopic or open duodenojejunostomy, division of the ligament of Treitz, or a modified Ladd procedure.^7-10 Removal of spinal implants and cast is unnecessary, except when lumbar spine hyperextension is the cause, in which case cast and metal implants must be removed to relieve the duodenum from the SMA.⁷The incidence of SMA syndrome after scoliosis surgery is 1% to 4.7%.^3,6,7 Our literature review of SMA syndrome after scoliosis surgery for AIS revealed 19 case reports over 45 years (Table 2).

Studies reported that the incidence of SMA syndrome was higher in certain groups based on the extent of spinal deformity and the Lenke classification system for scoliosis.^11,12 Specifically, groups with body mass index under the 25th percentile, Lenke B or C (laterally displaced, curved) scoliosis, and stiffer thoracic curves (<60% correction) have a higher incidence.¹² Overall, initial presentation of SMA syndrome generally consists of a combination of abdominal pain/distension, nausea, vomiting, and varying degrees of weight loss. Although the predominant cases are confirmed with upper GI contrast studies, some cases are confirmed with radiographs, laboratory (serum lipase) abnormalities, and correlated with their clinical presentation in order to direct their therapy.^13-15 For patients diagnosed with SMA syndrome, length of stay varies significantly, from 3 to 71 days. Time in hospital generally depends on ability to transition a patient to oral intake without complication. Eighty-five percent of reported cases of SMA syndrome after spinal surgery for AIS present within the first 2 weeks after surgery.^{1,6,7,9,13-19}Our patient’s case had a combination of unique features. First, he presented 19 days (almost 3 weeks) after surgery. We identified only 3 other case reports in which the patient presented later (most SMA syndrome symptoms present within 2 weeks of the spinal procedure). One patient presented on postoperative day 27 and was discharged with a nasojejunal tube because of an inability to tolerate oral intake.⁶ Another patient presented 40 days after surgery, underwent laparotomy (a fundal perforation was found), and died immediately afterward.¹⁵ A third presented 45 days after surgery and had a treatment experience similar to our patient’s: nasogastric decompression, intravenous fluids, nasojejunal tube feeding, and transition to oral intake before discharge.⁷Our case’s second unique feature is the 20-lb weight loss over 2 weeks—more than in most other cases over the same period. For patients with recorded weight loss, average weight loss was about 6.2 pounds per postoperative presentation week, and only 1 patient presented with a steeper trajectory of weight loss before presentation.¹⁸ Our patient may have waited longer to present to the ED or may have had a more severe case of the disease.

The third unique feature in this case is electrocardiogram findings. Although some cases briefly discussed electrolyte abnormalities, none presented evidence that these abnormalities caused cardiac changes.^6,16,18 The overall clinical significance of the QT prolongation in our patient’s case is unknown, as this finding was improved with correction of the electrolyte abnormalities and appropriate fluid replenishment.

Early recognition of nonspecific symptoms (eg, abdominal pain, tenderness, distension, bilious or projectile vomiting, hypoactive bowel sounds, anorexia) plays a key role in preventing severe morbidity and mortality from SMA syndrome after scoliosis surgery. Although many patients present in the semiclassic obstructed pattern, notable reasons for diagnostic delay include normal appetite and bowel sounds.³ For example, SMA syndrome may be misdiagnosed as stomach flu because of unfamiliarity with disease diagnosis and management.²⁰ Complications of SMA syndrome can potentially lead to aspiration pneumonia, acute gastric rupture, and cardiovascular collapse and death.

Am J Orthop. 2017;46(2):E124-E130. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Surgical intervention for cervical spondylosis and radiculopathy classically involves either an anterior or posterior approach for adequate decompression of the spinal cord and associated nerve roots.
• Combined anterior-posterior surgery for cervical spondylotic myelopathy is a relatively new technique that has previously been used for disorders of the thoracolumbar spine.
• Combined anterior-posterior cervical decompression and fusion for the treatment of cervical spondylotic myelopathy is associated with minor complications and excellent neurologic outcomes.
• Combined surgery can either be performed in a single day or in a staged manner, with current literature showing that same-day surgery is superior with respect to estimated blood loss and length of stay.

Cervical spondylotic myelopathy (CSM) is a degenerative disease characterized by progressive compression of the spinal cord. CSM has been found to be the most common cause of spinal impairment as well as the most frequently acquired cause of spinal dysfunction in people over 55 years of age.^1,2 If left untreated, this condition can reduce manual dexterity and cause gait disturbances, dysesthesias, and weakness in the extremities. When conservative treatments fail, surgical intervention often becomes the preferred course of action for CSM and/or myeloradiculopathy.

The surgical approach for CSM and other advanced cervical spine (CS) deformities varies and is often a source of debate. Being a relatively safe and effective procedure, anterior decompression with fusion is optimal in treating discogenic lesions causing myelopathy but is less effective in multilevel disease.^3,4 When pseudarthrosis, adjacent segment degeneration (ASD), and hardware failure are of concern, posterior decompressive laminectomy with instrumentation is a promising option.⁵ However, this method is less effective in restoring lordosis and can increase the risk for later clinical deterioration.⁶ There is a select subset of patients for whom a combined anterior-posterior approach is ideal.^7-9In cases in which a combined anterior-posterior approach is identified as the best treatment option, whether to perform the operation in a sequential or staged manner must be decided, and this question is another source of debate. Single-day surgery is sometimes anecdotally criticized as posing a greater risk to the patient. On the other hand, some comparative studies have shown no statistically significant difference in major complication rates between the 2 options.^10,11 More descriptive studies of combined anterior-posterior decompression and fusion (CAPDF) are needed to explore the efficacy of the procedure. In this article, we describe a study we conducted to characterize the operative data, perioperative complications, and short-term outcomes associated with CAPDF for the treatment of CSM in a select group of patients.

Methods

After receiving Institutional Review Board approval for this study (formal consent was not required), we retrospectively reviewed the charts of 21 patients who underwent CAPDF for CSM at our institution. All patients underwent surgery between February 2010 and March 2015. Criteria for inclusion in the study included same-day CAPDF for CSM. Staged procedures were excluded, as were combined procedures for the treatment of other diseases (eg, malignancies). All patients were operated on by the same primary surgeon (Dr. Davis) and co-surgeon (Dr. Labiak). The 1 patient who was lost to follow-up was excluded from the postoperative outcome analysis.

We reviewed the patients’ medical records for surgical consultations, operative reports, intraoperative reports, progress notes, and postoperative office visit reports. Demographic information included age, sex, body mass index, and preoperative risk factors, such as diabetes and tobacco use. All patients had been diagnosed with myelopathy. Clinical data included previous history of CS surgery, levels fused (and number of levels fused) anteriorly and posteriorly, operative time, estimated blood loss (EBL), length of stay (LOS), and perioperative complications. Short-term (3-month follow-up) neurologic improvement was determined both objectively, with the Nurick grading system,¹² and subjectively, with determination of patient quality of life before and after surgery and with neurologic examination.

Operative Technique: Anterior Approach

All operations were performed with continuous somatosensory evoked potential monitoring of both upper and lower extremities. Each patient, positioned supine with the head in a neutral position, underwent standard endotracheal intubation. Intubation was followed by a transverse incision and dissection down to the deep cervical fascia with maintenance of the carotid sheath laterally and tracheoesophageal complex medially. Interspaces were identified and later were confirmed with lateral radiographs. Discectomy, osteophytectomy, and removal of hypertrophied or calcified ligament were then performed until decompression was satisfactory. Corpectomies were not performed. Polyetheretherketone interbody spacers (Stryker) were used with autograft harvested from vertebral body resection. Low-profile screw-plate systems were placed. After completion of the anterior procedure, the patient was placed prone, with the head fixed in a Mayfield clamping device in neutral position and with all pressure points carefully padded.

 

Operative Technique: Posterior Approach

A midline incision was made through the skin and subcutaneous tissue to the level of the deep cervical fascia. Then, dissection was performed to the tips of the lateral masses. Instrumentation and fusion preceded spinal decompression. This order, chosen to preserve bony landmarks for guidance during instrumentation, did not interfere with subsequent decompression. Segmental spinal instrumentation was placed using lateral mass screw-rod fixation. After the laminae and ligamenta flava were bilaterally mobilized, the entire bony ligamentous complex spanning the area of fusion was removed en masse (most commonly C3–C7) in order to decrease the number of instrument passes near the spinal cord. Next, a modest foraminotomy was performed to extend the opening laterally and ensure adequate decompression of the nerve roots. Autograft harvested from the spinous processes and laminae was used. The posterior portion of the operation contributed significantly to blood loss and postoperative pain during the perioperative period. We recommend performing a very meticulous dissection to minimize these consequences. No patient in this study required a halo orthosis.

Results

Twenty-one patients with CSM were treated with CAPDF between February 2010 and March 2015 (Table 1).

Mean age was 62.1 years (range, 44-79 years). Nine patients were female, and 12 were male. The primary diagnosis was CSM, but several patients presented with associated conditions, including congenital cervical spinal stenosis (3 cases), cervical kyphotic deformity (3 cases), and ossification of posterior longitudinal ligament (OPLL; 4 cases). Two patients previously underwent CS surgery: anterior fusion at C4–C6 (patient 8) and separate anterior fusions (C5–C6, C6–C7) about 11 years apart (patient 16). For these 2 patients, combined anterior-posterior surgery was performed not to revise their fusions but to extend their constructs to address ASD. The 21-patient cohort had high rates of comorbidities: Thirteen patients (61.9%) were obese or morbidly obese, 6 (28.6%) had diabetes mellitus (insulin-dependent in 2 cases), and 13 (61.9%) had a history of tobacco use (6 of these patients used tobacco the previous year).

Table 2 summarizes the operative data. Mean number of levels fused was 2 (range, 1-3) anteriorly and 3 (range, 1-4) posteriorly.

C3–C4 was the most common fusion range anteriorly, and C3–C7 was the most common range posteriorly. Figure 1 shows the frequency of type of fusion performed both anteriorly and posteriorly.

Mean operative time, which included supine-to-prone repositioning at the end of the anterior operation, was 4 hours 55 minutes (range, 3:04-6:22). Mean EBL was 131 mL (range, 55-278 mL), and mean LOS was 5 days (range, 2-10 days).

Of the 21 patients, 9 (42.3%) had at least 1 complication during the perioperative period. Table 3 summarizes all encountered complications. Neither neurologic instability nor mortality was observed after surgery.

With the exception of 1 case of adjacent segment kyphosis, all complications were transient, yielding a long-term complication rate of 4.8%. The most frequently encountered complications were dysphagia (28.6%) and excessive wound discharge (9.5%). Dysphagia is a common complication after anterior cervical surgery, with exposure above C4 being a significant risk factor.¹³ Such exposure was found in 4 (66.7%) of the 6 patients with dysphagia. One patient in the study experienced kyphotic collapse below the level of fusion. Subsequent computed tomography showed no evidence of hardware failure, flexion/extension radiographs showed no progression of the kyphotic deformity, and the patient remained asymptomatic and did not undergo reoperation. The deformity was attributed to low bone quality, not to any abnormality in the surgical construct.

Patient 7 was lost to follow-up. For the other 20 patients, mean time to “3-month follow-up” was 96 days (range, 51-149 days). The most commonly noted improvements in quality of life included resolution of numbness, improvement in gait, and return to previous activities, such as walking and even exercising.

The most common improvements noted on neurologic examination included decreased hyperreflexia, less reproducible beats or complete absence of ankle clonus, gait improvement, and increased motor strength. Neurologic status was subjectively improved for 19 patients and unimproved for 1 patient; no patient’s neurologic status was worse (Table 4).

Mean Nurick grade was 1.9 before surgery and 1.1 after surgery (mean difference, 0.80; P < .001). Table 5 shows the distribution of patients’ Nurick grades before and after surgery.

Representative Case

Patient 15, a 53-year-old man, presented with complaints of dysesthesias of the hands. Focused neurologic evaluation at the time revealed limited CS range of motion on extension. The patient (Figures 2A-2D) was diffusely hyperreflexic and had pathologic spread in the upper extremities.

He underwent C3–C6 anterior discectomy, instrumentation, and fusion followed by C3–C6 posterior laminectomy, medial facetectomy, instrumentation, and fusion.

 

Discussion

Cervical myelopathy is a common yet frequently underdiagnosed disease, owing to the fact that many patients remain asymptomatic even after experiencing degenerative changes in the spinal column.^14-16 The additive effects of spondylosis, osteophyte formation, ligamentous hypertrophy, and listhesis lead to progressive canal and intervertebral foraminal compromise, ultimately producing the clinical syndromes of myelopathy and radiculopathy.¹⁷ The characteristic symptoms of CSM are known to have an insidious onset. In the early stages, patients note a subtle gait disturbance and later experience manual dexterity reductions and upper extremity dysesthesias.¹⁸ As the condition progresses and conservative management fails, surgical intervention is sought.

Nevertheless, the pursuit of surgical treatment for CSM remains somewhat controversial. Some authors have found no statistically significant difference between conservative and surgical management of mild to moderate CSM,¹⁹ whereas others have found that surgically treated patients had much better outcomes than their medically treated counterparts.²⁰ In 2010, Scardino and colleagues²¹ reported that CSM patients who were bedridden and/or wheelchair-bound with seemingly irreversible myelopathy were capable of neurologic improvement after surgical intervention. At the very least, what remains clear is that untreated CSM is known to follow an unpredictable course, with the condition deteriorating faster for some patients than others.²²Traditional anterior or posterior approaches, which can be used in the majority of cases of cervical spondylosis and/or radiculopathy, have been compared extensively.^23,24 The inverse relationship concerning the integrity of an anterior construct and the number of levels fused is a well-established clinical finding.^3,4,8,25-28 Laminectomy with fusion is not without its disadvantages: Cervical instability secondary to mechanical loss of posterior cervical support, and subsequent post-laminectomy kyphosis, is a common complication.²³ In cases in which more stability is required, the combined anterior-posterior approach is more promising than either approach alone. This technique has its roots in the treatment of several thoracolumbar spine disorders, including infections, scoliosis, trauma, and tumors.^29-31 More recently, the technique has been applied to CS disorders.

In 2008, Gok and colleagues³² retrospectively compared the results of anterior-only fusion and CAPDF for CSM. Forty-six patients underwent anterior surgery only, and 21 underwent CAPDF. The groups’ complication rates were similar: 28.6% (anterior only) and 24% (CAPDF); the incidence of ASD was lower in the combined group. Song and colleagues³³ conducted a similar study in 2010. They compared anterior fusion alone and CAPDF in treating degenerative cervical kyphosis. Results were strongly in favor of the combined technique, as it led to “greater correction of sagittal alignment, a better maintenance of correction angle, a higher rate of fusion, a lower rate of subsidence and lower complications.” Both studies established that, in a select group of patients, the benefits of CAPDF outweighed the risks. These findings, combined with our study’s findings of no major complications and the transience of minor complications, suggest CAPDF should not be considered too invasive or risky.

The results of our study also mirror those of 3 other studies on the use of CAPDF for CS disorders. In 1995, McAfee and colleagues³⁴ reported on a group of 100 patients with follow-up of 2 years or more. In most cases, the surgical indication was trauma, but neoplasm, infection, rheumatoid arthritis, and CSM were found as well. Outcomes were very favorable: improvement in a previous neurologic deficit (57/75 patients), ability to walk again (21/35 patients), no new neurologic deficits, and no hardware failures. In 2000, Schultz and colleagues³⁵ retrospectively reviewed the cases of 72 patients who underwent CAPDF for a variety of complex CS disorders. Two of the 72 experienced transient neurologic deficits, and, though the immediate complication rate was relatively high (32%), the long-term complication rate was down to 5%. In 2009, Konya and colleagues³⁶ retrospectively reviewed the cases of 40 patients who underwent CAPDF, primarily for CSM. Within 1 week after surgery, neurologic deficits were reduced in 36 patients; by 1 year after surgery, neurologic deficits were reduced in all 40 patients, and fusion was achieved in 39. These 3 studies^34-36 helped establish CAPDF of the CS as a viable and effective procedure that can be performed within a single day.

Although many physicians have achieved favorable results with single-day surgery, the decision to operate in a sequential or staged manner remains controversial. Some anecdotally claim CAPDF poses a greater operative risk to the patient. In 1991, the continuous procedure was found to involve less blood loss and shorter LOS while providing for better correction of severe spinal deformity in patients with scoliosis and rigid kyphosis.³⁷ Three more recent comparative studies examining the same issue in the treatment of CS diseases found staging did not reduce the complication rate and may in fact have been associated with higher complication rates, more blood loss, and longer total operative time and LOS.^10,11,38 Our study’s lower blood loss, shorter LOS, and lower major complication rate relative to the combined groups in all 3 of those studies are most likely attributable to our operating on a lower mean number of spinal levels and our restricting the surgical indication to CSM. The positive short-term outcomes and low rate of long-term complications in our study, combined with the data from these 3 comparative studies, suggest that same-day surgery is superior to staged surgery. A staged operation should be considered only if the patient cannot tolerate long periods under general anesthesia.

Many have advocated extending fusion down to T1 to prevent ASD at the C7–T1 disk space.^35,39,40 We decided against this approach for 2 reasons. First, at C7, lateral mass screws were always chosen over pedicle screws. When possible, shorter lateral mass screws were used at this level, making C7 much less rigid. Second, the C7–T1 facet capsule was maintained to preserve joint integrity. We suggest extending fusion down to T1 only if there is prior evidence of spinal disease and/or listhesis at C7–T1. Although long-term (many-year) follow-up is often desired, we specifically assessed short-term (3-month) outcomes. We have anecdotally found that degree of improvement often follows a predictable course after 3-month follow-up. If myelopathy resolves even to a small extent during the first 3 postoperative months, later improvement will likely follow an upward course. Conversely, if myelopathy does not improve during the first 3 months, further improvement is much less likely.

This trend in neurologic improvement likely is directly related to degree of myelopathy before surgery. Patients with CSM generally experience symptoms over an extended period and try conservative management before any surgical consultation. Although spinal ischemia is often resolved by decompression, permanent ischemic damage to the cord is not uncommon. In this setting, postoperative neurologic improvement is minimal or even nonexistent, and decompression is preventive rather than curative. In our study, 1 patient had no subjective improvement after surgery. At 3-month follow-up, magnetic resonance imaging showed notable myelomalacia without residual spinal cord compression. We attribute the failure of the ischemic changes to resolve to long-standing preoperative damage to the cord. Nevertheless, surgery stabilized the myelopathy and prevented further ischemic damage and clinical deterioration.

As is the case with any operation, patients must be carefully selected for CAPDF. Indications for CAPDF, as described by Kim and Alexander,⁷ include acute spinal trauma, post-laminectomy kyphosis, kyphotic deformity with intact posterior tension band, multilevel spondylosis and OPLL, and preexisting risk factors for pseudarthrosis. Clearly, the severity of each varies, and the pathologies are not mutually exclusive. We emphasize that these indications provide only a guideline for performing CAPDF, and patients must be selected on a case-by-case basis. All the patients in our study were symptomatic and exhibited significant compression of the spinal cord anteriorly and posteriorly at multiple levels. Several presented with concomitant pathologies, such as cervical kyphotic deformity, congenital spinal stenosis, and OPLL. In each case, the indication for surgical intervention was undoubted. We sought both to improve the patient’s baseline symptoms and to prevent further damage to the spinal cord.

This study had its limitations. First, its retrospective design predisposed it to a higher degree of bias. Second, because CAPDF is not commonly performed, the sample size was relatively small. Third, although it provided a descriptive analysis of CAPDF for CSM, the study did not use a direct comparison group to establish whether treatment within a single day or staged treatment was more beneficial for our cohort in particular. On the basis of prior experience and observation, we think performing the operation within a single day is much more beneficial for the patient. Our discussion of studies that have compared same-day and staged surgery supports this observation. Therefore, staged treatment was not recommended to our patients.

 

Conclusion

Few descriptive studies have explored CAPDF for CSM. Our study’s results showed the procedure was associated with minor complications and provided symptomatic relief for a majority of patients as early as 3 months after surgery. In addition, CAPDF can be successfully performed sequentially within a single day. As such, it represents an excellent option for treating multilevel symptomatic CSM cases that require more extensive spinal decompression and more stability.

Am J Orthop. 2017;46(2):E97-E104. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Surgical intervention for cervical spondylosis and radiculopathy classically involves either an anterior or posterior approach for adequate decompression of the spinal cord and associated nerve roots.
• Combined anterior-posterior surgery for cervical spondylotic myelopathy is a relatively new technique that has previously been used for disorders of the thoracolumbar spine.
• Combined anterior-posterior cervical decompression and fusion for the treatment of cervical spondylotic myelopathy is associated with minor complications and excellent neurologic outcomes.
• Combined surgery can either be performed in a single day or in a staged manner, with current literature showing that same-day surgery is superior with respect to estimated blood loss and length of stay.

Cervical spondylotic myelopathy (CSM) is a degenerative disease characterized by progressive compression of the spinal cord. CSM has been found to be the most common cause of spinal impairment as well as the most frequently acquired cause of spinal dysfunction in people over 55 years of age.^1,2 If left untreated, this condition can reduce manual dexterity and cause gait disturbances, dysesthesias, and weakness in the extremities. When conservative treatments fail, surgical intervention often becomes the preferred course of action for CSM and/or myeloradiculopathy.

The surgical approach for CSM and other advanced cervical spine (CS) deformities varies and is often a source of debate. Being a relatively safe and effective procedure, anterior decompression with fusion is optimal in treating discogenic lesions causing myelopathy but is less effective in multilevel disease.^3,4 When pseudarthrosis, adjacent segment degeneration (ASD), and hardware failure are of concern, posterior decompressive laminectomy with instrumentation is a promising option.⁵ However, this method is less effective in restoring lordosis and can increase the risk for later clinical deterioration.⁶ There is a select subset of patients for whom a combined anterior-posterior approach is ideal.^7-9In cases in which a combined anterior-posterior approach is identified as the best treatment option, whether to perform the operation in a sequential or staged manner must be decided, and this question is another source of debate. Single-day surgery is sometimes anecdotally criticized as posing a greater risk to the patient. On the other hand, some comparative studies have shown no statistically significant difference in major complication rates between the 2 options.^10,11 More descriptive studies of combined anterior-posterior decompression and fusion (CAPDF) are needed to explore the efficacy of the procedure. In this article, we describe a study we conducted to characterize the operative data, perioperative complications, and short-term outcomes associated with CAPDF for the treatment of CSM in a select group of patients.

Methods

After receiving Institutional Review Board approval for this study (formal consent was not required), we retrospectively reviewed the charts of 21 patients who underwent CAPDF for CSM at our institution. All patients underwent surgery between February 2010 and March 2015. Criteria for inclusion in the study included same-day CAPDF for CSM. Staged procedures were excluded, as were combined procedures for the treatment of other diseases (eg, malignancies). All patients were operated on by the same primary surgeon (Dr. Davis) and co-surgeon (Dr. Labiak). The 1 patient who was lost to follow-up was excluded from the postoperative outcome analysis.

We reviewed the patients’ medical records for surgical consultations, operative reports, intraoperative reports, progress notes, and postoperative office visit reports. Demographic information included age, sex, body mass index, and preoperative risk factors, such as diabetes and tobacco use. All patients had been diagnosed with myelopathy. Clinical data included previous history of CS surgery, levels fused (and number of levels fused) anteriorly and posteriorly, operative time, estimated blood loss (EBL), length of stay (LOS), and perioperative complications. Short-term (3-month follow-up) neurologic improvement was determined both objectively, with the Nurick grading system,¹² and subjectively, with determination of patient quality of life before and after surgery and with neurologic examination.

Operative Technique: Anterior Approach

All operations were performed with continuous somatosensory evoked potential monitoring of both upper and lower extremities. Each patient, positioned supine with the head in a neutral position, underwent standard endotracheal intubation. Intubation was followed by a transverse incision and dissection down to the deep cervical fascia with maintenance of the carotid sheath laterally and tracheoesophageal complex medially. Interspaces were identified and later were confirmed with lateral radiographs. Discectomy, osteophytectomy, and removal of hypertrophied or calcified ligament were then performed until decompression was satisfactory. Corpectomies were not performed. Polyetheretherketone interbody spacers (Stryker) were used with autograft harvested from vertebral body resection. Low-profile screw-plate systems were placed. After completion of the anterior procedure, the patient was placed prone, with the head fixed in a Mayfield clamping device in neutral position and with all pressure points carefully padded.

 

Operative Technique: Posterior Approach

A midline incision was made through the skin and subcutaneous tissue to the level of the deep cervical fascia. Then, dissection was performed to the tips of the lateral masses. Instrumentation and fusion preceded spinal decompression. This order, chosen to preserve bony landmarks for guidance during instrumentation, did not interfere with subsequent decompression. Segmental spinal instrumentation was placed using lateral mass screw-rod fixation. After the laminae and ligamenta flava were bilaterally mobilized, the entire bony ligamentous complex spanning the area of fusion was removed en masse (most commonly C3–C7) in order to decrease the number of instrument passes near the spinal cord. Next, a modest foraminotomy was performed to extend the opening laterally and ensure adequate decompression of the nerve roots. Autograft harvested from the spinous processes and laminae was used. The posterior portion of the operation contributed significantly to blood loss and postoperative pain during the perioperative period. We recommend performing a very meticulous dissection to minimize these consequences. No patient in this study required a halo orthosis.

Results

Twenty-one patients with CSM were treated with CAPDF between February 2010 and March 2015 (Table 1).

Mean age was 62.1 years (range, 44-79 years). Nine patients were female, and 12 were male. The primary diagnosis was CSM, but several patients presented with associated conditions, including congenital cervical spinal stenosis (3 cases), cervical kyphotic deformity (3 cases), and ossification of posterior longitudinal ligament (OPLL; 4 cases). Two patients previously underwent CS surgery: anterior fusion at C4–C6 (patient 8) and separate anterior fusions (C5–C6, C6–C7) about 11 years apart (patient 16). For these 2 patients, combined anterior-posterior surgery was performed not to revise their fusions but to extend their constructs to address ASD. The 21-patient cohort had high rates of comorbidities: Thirteen patients (61.9%) were obese or morbidly obese, 6 (28.6%) had diabetes mellitus (insulin-dependent in 2 cases), and 13 (61.9%) had a history of tobacco use (6 of these patients used tobacco the previous year).

Table 2 summarizes the operative data. Mean number of levels fused was 2 (range, 1-3) anteriorly and 3 (range, 1-4) posteriorly.

C3–C4 was the most common fusion range anteriorly, and C3–C7 was the most common range posteriorly. Figure 1 shows the frequency of type of fusion performed both anteriorly and posteriorly.

Mean operative time, which included supine-to-prone repositioning at the end of the anterior operation, was 4 hours 55 minutes (range, 3:04-6:22). Mean EBL was 131 mL (range, 55-278 mL), and mean LOS was 5 days (range, 2-10 days).

Of the 21 patients, 9 (42.3%) had at least 1 complication during the perioperative period. Table 3 summarizes all encountered complications. Neither neurologic instability nor mortality was observed after surgery.

With the exception of 1 case of adjacent segment kyphosis, all complications were transient, yielding a long-term complication rate of 4.8%. The most frequently encountered complications were dysphagia (28.6%) and excessive wound discharge (9.5%). Dysphagia is a common complication after anterior cervical surgery, with exposure above C4 being a significant risk factor.¹³ Such exposure was found in 4 (66.7%) of the 6 patients with dysphagia. One patient in the study experienced kyphotic collapse below the level of fusion. Subsequent computed tomography showed no evidence of hardware failure, flexion/extension radiographs showed no progression of the kyphotic deformity, and the patient remained asymptomatic and did not undergo reoperation. The deformity was attributed to low bone quality, not to any abnormality in the surgical construct.

Patient 7 was lost to follow-up. For the other 20 patients, mean time to “3-month follow-up” was 96 days (range, 51-149 days). The most commonly noted improvements in quality of life included resolution of numbness, improvement in gait, and return to previous activities, such as walking and even exercising.

The most common improvements noted on neurologic examination included decreased hyperreflexia, less reproducible beats or complete absence of ankle clonus, gait improvement, and increased motor strength. Neurologic status was subjectively improved for 19 patients and unimproved for 1 patient; no patient’s neurologic status was worse (Table 4).

Mean Nurick grade was 1.9 before surgery and 1.1 after surgery (mean difference, 0.80; P < .001). Table 5 shows the distribution of patients’ Nurick grades before and after surgery.

Representative Case

Patient 15, a 53-year-old man, presented with complaints of dysesthesias of the hands. Focused neurologic evaluation at the time revealed limited CS range of motion on extension. The patient (Figures 2A-2D) was diffusely hyperreflexic and had pathologic spread in the upper extremities.

He underwent C3–C6 anterior discectomy, instrumentation, and fusion followed by C3–C6 posterior laminectomy, medial facetectomy, instrumentation, and fusion.

 

Discussion

Cervical myelopathy is a common yet frequently underdiagnosed disease, owing to the fact that many patients remain asymptomatic even after experiencing degenerative changes in the spinal column.^14-16 The additive effects of spondylosis, osteophyte formation, ligamentous hypertrophy, and listhesis lead to progressive canal and intervertebral foraminal compromise, ultimately producing the clinical syndromes of myelopathy and radiculopathy.¹⁷ The characteristic symptoms of CSM are known to have an insidious onset. In the early stages, patients note a subtle gait disturbance and later experience manual dexterity reductions and upper extremity dysesthesias.¹⁸ As the condition progresses and conservative management fails, surgical intervention is sought.

Nevertheless, the pursuit of surgical treatment for CSM remains somewhat controversial. Some authors have found no statistically significant difference between conservative and surgical management of mild to moderate CSM,¹⁹ whereas others have found that surgically treated patients had much better outcomes than their medically treated counterparts.²⁰ In 2010, Scardino and colleagues²¹ reported that CSM patients who were bedridden and/or wheelchair-bound with seemingly irreversible myelopathy were capable of neurologic improvement after surgical intervention. At the very least, what remains clear is that untreated CSM is known to follow an unpredictable course, with the condition deteriorating faster for some patients than others.²²Traditional anterior or posterior approaches, which can be used in the majority of cases of cervical spondylosis and/or radiculopathy, have been compared extensively.^23,24 The inverse relationship concerning the integrity of an anterior construct and the number of levels fused is a well-established clinical finding.^3,4,8,25-28 Laminectomy with fusion is not without its disadvantages: Cervical instability secondary to mechanical loss of posterior cervical support, and subsequent post-laminectomy kyphosis, is a common complication.²³ In cases in which more stability is required, the combined anterior-posterior approach is more promising than either approach alone. This technique has its roots in the treatment of several thoracolumbar spine disorders, including infections, scoliosis, trauma, and tumors.^29-31 More recently, the technique has been applied to CS disorders.

In 2008, Gok and colleagues³² retrospectively compared the results of anterior-only fusion and CAPDF for CSM. Forty-six patients underwent anterior surgery only, and 21 underwent CAPDF. The groups’ complication rates were similar: 28.6% (anterior only) and 24% (CAPDF); the incidence of ASD was lower in the combined group. Song and colleagues³³ conducted a similar study in 2010. They compared anterior fusion alone and CAPDF in treating degenerative cervical kyphosis. Results were strongly in favor of the combined technique, as it led to “greater correction of sagittal alignment, a better maintenance of correction angle, a higher rate of fusion, a lower rate of subsidence and lower complications.” Both studies established that, in a select group of patients, the benefits of CAPDF outweighed the risks. These findings, combined with our study’s findings of no major complications and the transience of minor complications, suggest CAPDF should not be considered too invasive or risky.

The results of our study also mirror those of 3 other studies on the use of CAPDF for CS disorders. In 1995, McAfee and colleagues³⁴ reported on a group of 100 patients with follow-up of 2 years or more. In most cases, the surgical indication was trauma, but neoplasm, infection, rheumatoid arthritis, and CSM were found as well. Outcomes were very favorable: improvement in a previous neurologic deficit (57/75 patients), ability to walk again (21/35 patients), no new neurologic deficits, and no hardware failures. In 2000, Schultz and colleagues³⁵ retrospectively reviewed the cases of 72 patients who underwent CAPDF for a variety of complex CS disorders. Two of the 72 experienced transient neurologic deficits, and, though the immediate complication rate was relatively high (32%), the long-term complication rate was down to 5%. In 2009, Konya and colleagues³⁶ retrospectively reviewed the cases of 40 patients who underwent CAPDF, primarily for CSM. Within 1 week after surgery, neurologic deficits were reduced in 36 patients; by 1 year after surgery, neurologic deficits were reduced in all 40 patients, and fusion was achieved in 39. These 3 studies^34-36 helped establish CAPDF of the CS as a viable and effective procedure that can be performed within a single day.

Although many physicians have achieved favorable results with single-day surgery, the decision to operate in a sequential or staged manner remains controversial. Some anecdotally claim CAPDF poses a greater operative risk to the patient. In 1991, the continuous procedure was found to involve less blood loss and shorter LOS while providing for better correction of severe spinal deformity in patients with scoliosis and rigid kyphosis.³⁷ Three more recent comparative studies examining the same issue in the treatment of CS diseases found staging did not reduce the complication rate and may in fact have been associated with higher complication rates, more blood loss, and longer total operative time and LOS.^10,11,38 Our study’s lower blood loss, shorter LOS, and lower major complication rate relative to the combined groups in all 3 of those studies are most likely attributable to our operating on a lower mean number of spinal levels and our restricting the surgical indication to CSM. The positive short-term outcomes and low rate of long-term complications in our study, combined with the data from these 3 comparative studies, suggest that same-day surgery is superior to staged surgery. A staged operation should be considered only if the patient cannot tolerate long periods under general anesthesia.

Many have advocated extending fusion down to T1 to prevent ASD at the C7–T1 disk space.^35,39,40 We decided against this approach for 2 reasons. First, at C7, lateral mass screws were always chosen over pedicle screws. When possible, shorter lateral mass screws were used at this level, making C7 much less rigid. Second, the C7–T1 facet capsule was maintained to preserve joint integrity. We suggest extending fusion down to T1 only if there is prior evidence of spinal disease and/or listhesis at C7–T1. Although long-term (many-year) follow-up is often desired, we specifically assessed short-term (3-month) outcomes. We have anecdotally found that degree of improvement often follows a predictable course after 3-month follow-up. If myelopathy resolves even to a small extent during the first 3 postoperative months, later improvement will likely follow an upward course. Conversely, if myelopathy does not improve during the first 3 months, further improvement is much less likely.

This trend in neurologic improvement likely is directly related to degree of myelopathy before surgery. Patients with CSM generally experience symptoms over an extended period and try conservative management before any surgical consultation. Although spinal ischemia is often resolved by decompression, permanent ischemic damage to the cord is not uncommon. In this setting, postoperative neurologic improvement is minimal or even nonexistent, and decompression is preventive rather than curative. In our study, 1 patient had no subjective improvement after surgery. At 3-month follow-up, magnetic resonance imaging showed notable myelomalacia without residual spinal cord compression. We attribute the failure of the ischemic changes to resolve to long-standing preoperative damage to the cord. Nevertheless, surgery stabilized the myelopathy and prevented further ischemic damage and clinical deterioration.

As is the case with any operation, patients must be carefully selected for CAPDF. Indications for CAPDF, as described by Kim and Alexander,⁷ include acute spinal trauma, post-laminectomy kyphosis, kyphotic deformity with intact posterior tension band, multilevel spondylosis and OPLL, and preexisting risk factors for pseudarthrosis. Clearly, the severity of each varies, and the pathologies are not mutually exclusive. We emphasize that these indications provide only a guideline for performing CAPDF, and patients must be selected on a case-by-case basis. All the patients in our study were symptomatic and exhibited significant compression of the spinal cord anteriorly and posteriorly at multiple levels. Several presented with concomitant pathologies, such as cervical kyphotic deformity, congenital spinal stenosis, and OPLL. In each case, the indication for surgical intervention was undoubted. We sought both to improve the patient’s baseline symptoms and to prevent further damage to the spinal cord.

This study had its limitations. First, its retrospective design predisposed it to a higher degree of bias. Second, because CAPDF is not commonly performed, the sample size was relatively small. Third, although it provided a descriptive analysis of CAPDF for CSM, the study did not use a direct comparison group to establish whether treatment within a single day or staged treatment was more beneficial for our cohort in particular. On the basis of prior experience and observation, we think performing the operation within a single day is much more beneficial for the patient. Our discussion of studies that have compared same-day and staged surgery supports this observation. Therefore, staged treatment was not recommended to our patients.

 

Conclusion

Few descriptive studies have explored CAPDF for CSM. Our study’s results showed the procedure was associated with minor complications and provided symptomatic relief for a majority of patients as early as 3 months after surgery. In addition, CAPDF can be successfully performed sequentially within a single day. As such, it represents an excellent option for treating multilevel symptomatic CSM cases that require more extensive spinal decompression and more stability.

Am J Orthop. 2017;46(2):E97-E104. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Surgical intervention for cervical spondylosis and radiculopathy classically involves either an anterior or posterior approach for adequate decompression of the spinal cord and associated nerve roots.
• Combined anterior-posterior surgery for cervical spondylotic myelopathy is a relatively new technique that has previously been used for disorders of the thoracolumbar spine.
• Combined anterior-posterior cervical decompression and fusion for the treatment of cervical spondylotic myelopathy is associated with minor complications and excellent neurologic outcomes.
• Combined surgery can either be performed in a single day or in a staged manner, with current literature showing that same-day surgery is superior with respect to estimated blood loss and length of stay.

Cervical spondylotic myelopathy (CSM) is a degenerative disease characterized by progressive compression of the spinal cord. CSM has been found to be the most common cause of spinal impairment as well as the most frequently acquired cause of spinal dysfunction in people over 55 years of age.^1,2 If left untreated, this condition can reduce manual dexterity and cause gait disturbances, dysesthesias, and weakness in the extremities. When conservative treatments fail, surgical intervention often becomes the preferred course of action for CSM and/or myeloradiculopathy.

The surgical approach for CSM and other advanced cervical spine (CS) deformities varies and is often a source of debate. Being a relatively safe and effective procedure, anterior decompression with fusion is optimal in treating discogenic lesions causing myelopathy but is less effective in multilevel disease.^3,4 When pseudarthrosis, adjacent segment degeneration (ASD), and hardware failure are of concern, posterior decompressive laminectomy with instrumentation is a promising option.⁵ However, this method is less effective in restoring lordosis and can increase the risk for later clinical deterioration.⁶ There is a select subset of patients for whom a combined anterior-posterior approach is ideal.^7-9In cases in which a combined anterior-posterior approach is identified as the best treatment option, whether to perform the operation in a sequential or staged manner must be decided, and this question is another source of debate. Single-day surgery is sometimes anecdotally criticized as posing a greater risk to the patient. On the other hand, some comparative studies have shown no statistically significant difference in major complication rates between the 2 options.^10,11 More descriptive studies of combined anterior-posterior decompression and fusion (CAPDF) are needed to explore the efficacy of the procedure. In this article, we describe a study we conducted to characterize the operative data, perioperative complications, and short-term outcomes associated with CAPDF for the treatment of CSM in a select group of patients.

Methods

After receiving Institutional Review Board approval for this study (formal consent was not required), we retrospectively reviewed the charts of 21 patients who underwent CAPDF for CSM at our institution. All patients underwent surgery between February 2010 and March 2015. Criteria for inclusion in the study included same-day CAPDF for CSM. Staged procedures were excluded, as were combined procedures for the treatment of other diseases (eg, malignancies). All patients were operated on by the same primary surgeon (Dr. Davis) and co-surgeon (Dr. Labiak). The 1 patient who was lost to follow-up was excluded from the postoperative outcome analysis.

We reviewed the patients’ medical records for surgical consultations, operative reports, intraoperative reports, progress notes, and postoperative office visit reports. Demographic information included age, sex, body mass index, and preoperative risk factors, such as diabetes and tobacco use. All patients had been diagnosed with myelopathy. Clinical data included previous history of CS surgery, levels fused (and number of levels fused) anteriorly and posteriorly, operative time, estimated blood loss (EBL), length of stay (LOS), and perioperative complications. Short-term (3-month follow-up) neurologic improvement was determined both objectively, with the Nurick grading system,¹² and subjectively, with determination of patient quality of life before and after surgery and with neurologic examination.

Operative Technique: Anterior Approach

All operations were performed with continuous somatosensory evoked potential monitoring of both upper and lower extremities. Each patient, positioned supine with the head in a neutral position, underwent standard endotracheal intubation. Intubation was followed by a transverse incision and dissection down to the deep cervical fascia with maintenance of the carotid sheath laterally and tracheoesophageal complex medially. Interspaces were identified and later were confirmed with lateral radiographs. Discectomy, osteophytectomy, and removal of hypertrophied or calcified ligament were then performed until decompression was satisfactory. Corpectomies were not performed. Polyetheretherketone interbody spacers (Stryker) were used with autograft harvested from vertebral body resection. Low-profile screw-plate systems were placed. After completion of the anterior procedure, the patient was placed prone, with the head fixed in a Mayfield clamping device in neutral position and with all pressure points carefully padded.

 

Operative Technique: Posterior Approach

A midline incision was made through the skin and subcutaneous tissue to the level of the deep cervical fascia. Then, dissection was performed to the tips of the lateral masses. Instrumentation and fusion preceded spinal decompression. This order, chosen to preserve bony landmarks for guidance during instrumentation, did not interfere with subsequent decompression. Segmental spinal instrumentation was placed using lateral mass screw-rod fixation. After the laminae and ligamenta flava were bilaterally mobilized, the entire bony ligamentous complex spanning the area of fusion was removed en masse (most commonly C3–C7) in order to decrease the number of instrument passes near the spinal cord. Next, a modest foraminotomy was performed to extend the opening laterally and ensure adequate decompression of the nerve roots. Autograft harvested from the spinous processes and laminae was used. The posterior portion of the operation contributed significantly to blood loss and postoperative pain during the perioperative period. We recommend performing a very meticulous dissection to minimize these consequences. No patient in this study required a halo orthosis.

Results

Twenty-one patients with CSM were treated with CAPDF between February 2010 and March 2015 (Table 1).

Mean age was 62.1 years (range, 44-79 years). Nine patients were female, and 12 were male. The primary diagnosis was CSM, but several patients presented with associated conditions, including congenital cervical spinal stenosis (3 cases), cervical kyphotic deformity (3 cases), and ossification of posterior longitudinal ligament (OPLL; 4 cases). Two patients previously underwent CS surgery: anterior fusion at C4–C6 (patient 8) and separate anterior fusions (C5–C6, C6–C7) about 11 years apart (patient 16). For these 2 patients, combined anterior-posterior surgery was performed not to revise their fusions but to extend their constructs to address ASD. The 21-patient cohort had high rates of comorbidities: Thirteen patients (61.9%) were obese or morbidly obese, 6 (28.6%) had diabetes mellitus (insulin-dependent in 2 cases), and 13 (61.9%) had a history of tobacco use (6 of these patients used tobacco the previous year).

Table 2 summarizes the operative data. Mean number of levels fused was 2 (range, 1-3) anteriorly and 3 (range, 1-4) posteriorly.

C3–C4 was the most common fusion range anteriorly, and C3–C7 was the most common range posteriorly. Figure 1 shows the frequency of type of fusion performed both anteriorly and posteriorly.

Mean operative time, which included supine-to-prone repositioning at the end of the anterior operation, was 4 hours 55 minutes (range, 3:04-6:22). Mean EBL was 131 mL (range, 55-278 mL), and mean LOS was 5 days (range, 2-10 days).

Of the 21 patients, 9 (42.3%) had at least 1 complication during the perioperative period. Table 3 summarizes all encountered complications. Neither neurologic instability nor mortality was observed after surgery.

With the exception of 1 case of adjacent segment kyphosis, all complications were transient, yielding a long-term complication rate of 4.8%. The most frequently encountered complications were dysphagia (28.6%) and excessive wound discharge (9.5%). Dysphagia is a common complication after anterior cervical surgery, with exposure above C4 being a significant risk factor.¹³ Such exposure was found in 4 (66.7%) of the 6 patients with dysphagia. One patient in the study experienced kyphotic collapse below the level of fusion. Subsequent computed tomography showed no evidence of hardware failure, flexion/extension radiographs showed no progression of the kyphotic deformity, and the patient remained asymptomatic and did not undergo reoperation. The deformity was attributed to low bone quality, not to any abnormality in the surgical construct.

Patient 7 was lost to follow-up. For the other 20 patients, mean time to “3-month follow-up” was 96 days (range, 51-149 days). The most commonly noted improvements in quality of life included resolution of numbness, improvement in gait, and return to previous activities, such as walking and even exercising.

The most common improvements noted on neurologic examination included decreased hyperreflexia, less reproducible beats or complete absence of ankle clonus, gait improvement, and increased motor strength. Neurologic status was subjectively improved for 19 patients and unimproved for 1 patient; no patient’s neurologic status was worse (Table 4).

Mean Nurick grade was 1.9 before surgery and 1.1 after surgery (mean difference, 0.80; P < .001). Table 5 shows the distribution of patients’ Nurick grades before and after surgery.

Representative Case

Patient 15, a 53-year-old man, presented with complaints of dysesthesias of the hands. Focused neurologic evaluation at the time revealed limited CS range of motion on extension. The patient (Figures 2A-2D) was diffusely hyperreflexic and had pathologic spread in the upper extremities.

He underwent C3–C6 anterior discectomy, instrumentation, and fusion followed by C3–C6 posterior laminectomy, medial facetectomy, instrumentation, and fusion.

 

Discussion

Cervical myelopathy is a common yet frequently underdiagnosed disease, owing to the fact that many patients remain asymptomatic even after experiencing degenerative changes in the spinal column.^14-16 The additive effects of spondylosis, osteophyte formation, ligamentous hypertrophy, and listhesis lead to progressive canal and intervertebral foraminal compromise, ultimately producing the clinical syndromes of myelopathy and radiculopathy.¹⁷ The characteristic symptoms of CSM are known to have an insidious onset. In the early stages, patients note a subtle gait disturbance and later experience manual dexterity reductions and upper extremity dysesthesias.¹⁸ As the condition progresses and conservative management fails, surgical intervention is sought.

Nevertheless, the pursuit of surgical treatment for CSM remains somewhat controversial. Some authors have found no statistically significant difference between conservative and surgical management of mild to moderate CSM,¹⁹ whereas others have found that surgically treated patients had much better outcomes than their medically treated counterparts.²⁰ In 2010, Scardino and colleagues²¹ reported that CSM patients who were bedridden and/or wheelchair-bound with seemingly irreversible myelopathy were capable of neurologic improvement after surgical intervention. At the very least, what remains clear is that untreated CSM is known to follow an unpredictable course, with the condition deteriorating faster for some patients than others.²²Traditional anterior or posterior approaches, which can be used in the majority of cases of cervical spondylosis and/or radiculopathy, have been compared extensively.^23,24 The inverse relationship concerning the integrity of an anterior construct and the number of levels fused is a well-established clinical finding.^3,4,8,25-28 Laminectomy with fusion is not without its disadvantages: Cervical instability secondary to mechanical loss of posterior cervical support, and subsequent post-laminectomy kyphosis, is a common complication.²³ In cases in which more stability is required, the combined anterior-posterior approach is more promising than either approach alone. This technique has its roots in the treatment of several thoracolumbar spine disorders, including infections, scoliosis, trauma, and tumors.^29-31 More recently, the technique has been applied to CS disorders.

In 2008, Gok and colleagues³² retrospectively compared the results of anterior-only fusion and CAPDF for CSM. Forty-six patients underwent anterior surgery only, and 21 underwent CAPDF. The groups’ complication rates were similar: 28.6% (anterior only) and 24% (CAPDF); the incidence of ASD was lower in the combined group. Song and colleagues³³ conducted a similar study in 2010. They compared anterior fusion alone and CAPDF in treating degenerative cervical kyphosis. Results were strongly in favor of the combined technique, as it led to “greater correction of sagittal alignment, a better maintenance of correction angle, a higher rate of fusion, a lower rate of subsidence and lower complications.” Both studies established that, in a select group of patients, the benefits of CAPDF outweighed the risks. These findings, combined with our study’s findings of no major complications and the transience of minor complications, suggest CAPDF should not be considered too invasive or risky.

The results of our study also mirror those of 3 other studies on the use of CAPDF for CS disorders. In 1995, McAfee and colleagues³⁴ reported on a group of 100 patients with follow-up of 2 years or more. In most cases, the surgical indication was trauma, but neoplasm, infection, rheumatoid arthritis, and CSM were found as well. Outcomes were very favorable: improvement in a previous neurologic deficit (57/75 patients), ability to walk again (21/35 patients), no new neurologic deficits, and no hardware failures. In 2000, Schultz and colleagues³⁵ retrospectively reviewed the cases of 72 patients who underwent CAPDF for a variety of complex CS disorders. Two of the 72 experienced transient neurologic deficits, and, though the immediate complication rate was relatively high (32%), the long-term complication rate was down to 5%. In 2009, Konya and colleagues³⁶ retrospectively reviewed the cases of 40 patients who underwent CAPDF, primarily for CSM. Within 1 week after surgery, neurologic deficits were reduced in 36 patients; by 1 year after surgery, neurologic deficits were reduced in all 40 patients, and fusion was achieved in 39. These 3 studies^34-36 helped establish CAPDF of the CS as a viable and effective procedure that can be performed within a single day.

Although many physicians have achieved favorable results with single-day surgery, the decision to operate in a sequential or staged manner remains controversial. Some anecdotally claim CAPDF poses a greater operative risk to the patient. In 1991, the continuous procedure was found to involve less blood loss and shorter LOS while providing for better correction of severe spinal deformity in patients with scoliosis and rigid kyphosis.³⁷ Three more recent comparative studies examining the same issue in the treatment of CS diseases found staging did not reduce the complication rate and may in fact have been associated with higher complication rates, more blood loss, and longer total operative time and LOS.^10,11,38 Our study’s lower blood loss, shorter LOS, and lower major complication rate relative to the combined groups in all 3 of those studies are most likely attributable to our operating on a lower mean number of spinal levels and our restricting the surgical indication to CSM. The positive short-term outcomes and low rate of long-term complications in our study, combined with the data from these 3 comparative studies, suggest that same-day surgery is superior to staged surgery. A staged operation should be considered only if the patient cannot tolerate long periods under general anesthesia.

Many have advocated extending fusion down to T1 to prevent ASD at the C7–T1 disk space.^35,39,40 We decided against this approach for 2 reasons. First, at C7, lateral mass screws were always chosen over pedicle screws. When possible, shorter lateral mass screws were used at this level, making C7 much less rigid. Second, the C7–T1 facet capsule was maintained to preserve joint integrity. We suggest extending fusion down to T1 only if there is prior evidence of spinal disease and/or listhesis at C7–T1. Although long-term (many-year) follow-up is often desired, we specifically assessed short-term (3-month) outcomes. We have anecdotally found that degree of improvement often follows a predictable course after 3-month follow-up. If myelopathy resolves even to a small extent during the first 3 postoperative months, later improvement will likely follow an upward course. Conversely, if myelopathy does not improve during the first 3 months, further improvement is much less likely.

This trend in neurologic improvement likely is directly related to degree of myelopathy before surgery. Patients with CSM generally experience symptoms over an extended period and try conservative management before any surgical consultation. Although spinal ischemia is often resolved by decompression, permanent ischemic damage to the cord is not uncommon. In this setting, postoperative neurologic improvement is minimal or even nonexistent, and decompression is preventive rather than curative. In our study, 1 patient had no subjective improvement after surgery. At 3-month follow-up, magnetic resonance imaging showed notable myelomalacia without residual spinal cord compression. We attribute the failure of the ischemic changes to resolve to long-standing preoperative damage to the cord. Nevertheless, surgery stabilized the myelopathy and prevented further ischemic damage and clinical deterioration.

As is the case with any operation, patients must be carefully selected for CAPDF. Indications for CAPDF, as described by Kim and Alexander,⁷ include acute spinal trauma, post-laminectomy kyphosis, kyphotic deformity with intact posterior tension band, multilevel spondylosis and OPLL, and preexisting risk factors for pseudarthrosis. Clearly, the severity of each varies, and the pathologies are not mutually exclusive. We emphasize that these indications provide only a guideline for performing CAPDF, and patients must be selected on a case-by-case basis. All the patients in our study were symptomatic and exhibited significant compression of the spinal cord anteriorly and posteriorly at multiple levels. Several presented with concomitant pathologies, such as cervical kyphotic deformity, congenital spinal stenosis, and OPLL. In each case, the indication for surgical intervention was undoubted. We sought both to improve the patient’s baseline symptoms and to prevent further damage to the spinal cord.

This study had its limitations. First, its retrospective design predisposed it to a higher degree of bias. Second, because CAPDF is not commonly performed, the sample size was relatively small. Third, although it provided a descriptive analysis of CAPDF for CSM, the study did not use a direct comparison group to establish whether treatment within a single day or staged treatment was more beneficial for our cohort in particular. On the basis of prior experience and observation, we think performing the operation within a single day is much more beneficial for the patient. Our discussion of studies that have compared same-day and staged surgery supports this observation. Therefore, staged treatment was not recommended to our patients.

 

Conclusion

Few descriptive studies have explored CAPDF for CSM. Our study’s results showed the procedure was associated with minor complications and provided symptomatic relief for a majority of patients as early as 3 months after surgery. In addition, CAPDF can be successfully performed sequentially within a single day. As such, it represents an excellent option for treating multilevel symptomatic CSM cases that require more extensive spinal decompression and more stability.

Am J Orthop. 2017;46(2):E97-E104. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Music therapists use patient-preferred live music, increasing neurologic cues that enhance movement—a seminal recovery function in postoperative spine patients.
• Music therapy is an evidence-based, integrative treatment addressing body, mind, and spirit.
• Tension release through music therapy can serve as a critical mechanism for building resilience related to pain management.
• Music therapy and music medicine are distinct forms of clinical practice that focus on mind-body integration in the healing process.
• Music therapists, board-certified and licensed by the state as recognized healthcare professionals, address pain management, which is an increasing subspecialty in postoperative care.

About 70% of people in the United States experience at least 1 episode of back pain in their lifetime,¹ and more than 5 million are temporarily or permanently disabled by spinal disorders.^2-4 Some require surgery, which may rectify injury, but pain during recovery is often inevitable, and the road to recovery is not guaranteed to be smooth.^5-20

Postoperative spine patients are at major risk for pain management challenges.^14,15,18,20 Treatment is primarily pharmacologic and based on the surgical team’s pain management orders. Nursing care consists of monitoring the airway, vital signs, and neurovascular status and having patients rate their pain on a visual analog scale (VAS; 0 = no pain, 10 = worst pain imaginable). Nurses have the challenge of monitoring and continually assessing to make sure patients are achieving the optimal outcomes, particularly during the immediate postoperative period, when pain and anxiety are prominently increased.

Variability in spine surgery outcomes can be explained at least partly on the basis of prognostic psychological factors, including hypochondriasis, hysteria, depression, and poor pain coping strategies (eg, catastrophizing).²¹ In spine surgery patients, kinesiophobia (fear of moving) is a common component of distress that can impede recuperation.^21-23Psychological interventions that assist with the secondary stressors associated with pain and loss during physical recuperation are recommended, with increased attention given to the importance of treating the whole person: body, mind, and spirit.^24-29 Conventional pain-alleviating medical interventions can be enhanced with integrative therapies that empower patients to marshal their inner resources during recovery.^25-28Music therapy may be particularly suited to this effort, as it is adaptable to the patient’s individual and culturally specific needs.^29-33

Rationale for Live Music

Pain is subjective and personal, and warrants an individualized approach to care. There is a body of music medicine research on the use of recorded music in modulating psychological and physiological factors in pain perception.^30,32,34-54 This research supports the unique relationship of music to well-being, and the understanding that controlling any of these factors affects the duration, intensity, and quality of that experience.^41,43,52

These findings provide incentive for breathing-entrained music therapy interventions, which enhance the relaxation response and release of pain-related tension;^32,55-58 empower patients to unlock physical and emotional tension;^32,57,58 provide a channel for expression and body movement; and enhance blood flow and/or alleviate pain by activating neurologic areas involved in the experience of pain.^59-62Studies have found that physical endurance may be enhanced when movement is rhythmically coordinated with a musical stimulus.^63-66 Music may prolong physical endurance by inhibiting psychological feedback associated with physical exertion related to fatigue, which may translate into accelerated recovery periods. When we listen to a rhythmic sound, our brains tend to automatically synchronize, or entrain, to external rhythmic cues that can stimulate increased motor control and coordination.⁶³ Sound can arouse and raise the excitability of spinal motor neurons mediated by auditory-motor neuronal connections on the brain stem and spinal cord level.^64-66 Rhythmically organized sounds serve as a neurological function in our capacity to organize predictable timing cues that are apparent in music, and may result in an effective treatment intervention in recovery.^63,64

Music Therapy in Recovery From Spine Surgery

In music therapy, music is used within a therapeutic relationship to support or affect change in the patient and the treatment regimen.^32,33,56-58 Research on music therapy with patients who are recovering from spine surgery is scant.^67-69 Kleiber and Adamek⁶⁷ studied perceptions of music therapy in 8 adolescents after spinal fusion surgery. In their study, a music therapist provided patients with a postoperative music therapy session focusing on the use of patient-preferred live music for relaxation and expression. Although their qualitative query was based on a therapeutic approach similar to that used in the present study, only 1 session was offered during the recovery period, and follow-up was conducted by survey invitation and telephone. In addition, the number of participants was small, and there was no quantitative measure of pain or other symptoms.

 

Another study focused on the effects of listening to music on pain intensity and distress after spine surgery.⁶⁸ Patients in the study’s music group made their selections from prerecorded classical music and domestic and international popular songs from various genres and listened to their chosen recordings 30 minutes a day. Although the study was not a music therapy study per se, it showed a positive impact of listening to music on anxiety and pain perception in 60 adults who were randomly assigned to the music group or to a non-music control group (n = 30 in each). Differences between the music and control groups’ VAS ratings of anxiety (Ps = .018-.001) and pain (P = .001) were statistically significant.

Different from our study, the aforementioned studies did not include tension release–focused live music offered within a therapeutic relationship. Our 1.5-year pilot study, conducted prior to the present study indicated that music therapy led to increased resilience and recovery mechanisms.⁵⁸

Methods

Our mixed-methods study design combined standard medical treatment with integrative music therapy interventions based on pain assessments to better understand the effects of music therapy on the recovery of patients after spine surgery.

The Spine Institute of New York within the Department of Orthopedic Surgery at Mount Sinai Beth Israel provides surgical treatment of common spinal cord conditions. Prioritizing patient satisfaction and positive outcomes,^27,28 the institute integrates music therapy through the Louis Armstrong Center for Music and Medicine to enhance treatment of pain symptoms.

Patients were recruited by the research team as per the daily surgical schedule, or through referral by the medical team or patient care navigator. Sixty patients (35 female, 25 male) ranging in age from 40 to 55 years underwent anterior, posterior, or anterior-posterior spinal fusion and were enrolled in the study after signing a participation consent form. Minorities, women, and patients with Medicaid and Medicare were included. Patients who received a diagnosis of clinical psychosis or depression prior to spine injury were excluded.

The experimental group received music therapy plus standard care (medical and nursing care with scheduled pharmacologic pain intervention), and a wait-listed control group received standard care only. A randomization chart created by a blinded statistician who did not have access to the patient census determined the intervention–nonintervention schedule. Patients in the music therapy group received one 30-minute music therapy session during an 8-hour period within 72 hours after surgery.

For both groups, measurements were completed before and after the study window. Control patients were offered music therapy after completion of the post-intervention surveys in order to minimize the ethical dilemma of denying potentially helpful pain intervention. For this same reason, both groups were given the option of receiving follow-up music therapy sessions for the duration of their hospitalization.

The research team consisted of 2 licensed, board-certified music therapists. In addition, Master’s-level music therapy interns completing clinical hours as part of the trajectory for board certification served on the research team over the 5-year period 2009 to 2014, and 13 blinded research assistants helped with enrolling and collecting data on patients.

Intervention

Each music therapy session included a warm-up phase of verbal or musical discourse. Next was the treatment phase, which was based on patient need as assessed during warm-up. Treatment options included use of patient-preferred live music that supported tension release/relaxation through incentive-based clinical improvisation, singing, and/or rhythmic drumming or through breathwork and visualization. Psychoeducation about mind–body awareness through the use of breath and imagery was introduced and explained by the therapist at this time.

The improvised music intervention was focused on making salient the natural harmonic tension-resolution cycles that occur in music and that were entrained to the patient’s presentation (respiratory rate, verbal report, clinical presentation). When patient-preferred precomposed songs were used, tension resolution was achieved by sustaining cadence and resolution, also entrained to the patient’s respiratory cycles.^32,57,58

After the music therapy intervention, a period of closure or integration was facilitated by the therapist contingent on the patient’s degree of alertness. If awake, the patient was supported in a reflexive process of thoughts, impressions, or issues that may have contributed to the overall experience. If the patient was asleep, the researcher returned within 30 minutes for post-intervention interviewing. Interview information was recorded in a qualitative post-participation survey. To prevent bias, researchers who were not the treating clinicians conducted the surveys.

Outcome Measures

Both primary and secondary outcome measures were collected before and after the intervention. The primary outcome measure was VAS pain ratings, and the secondary outcome measures were scores on the Hospital Anxiety and Depression Scale (HADS), the Tampa Scale for Kinesiophobia (TSK), and the Color Analysis Scale (CAS).

 

VAS. With the VAS, images are used to rate pain. The scale has points labeled 0 to 10 and corresponding faces representing progression in pain intensity. The scale is quickly rendered and can be interpreted according to the patient’s recovery phase at time of rendering.

HADS. The HADS⁷⁰ provides a specific baseline for anxiety and depression as an indicator of how the patient might fare during hospitalization (admission through recovery and discharge).

TSK. The TSK⁷¹ provides insight into the patient’s perception of fear-related movement, which is an important factor in this study because of the movement required for rehabilitation. We used a shortened version of the TSK to accommodate the sensitive threshold for pain tolerance and pharmacologic side effects commonly experienced by spine patients.

CAS. The CAS was developed at the Louis Armstrong Center for Music and Medicine to assess comorbidities and dynamic aspects of pain. Through a coloring exercise, patients illustrate their pain experience, which gives tangible form to the abstract experience of pain.

Coding

We collected patients’ demographic data, including age, sex, and diagnoses. Clinical indicators of the preoperative baseline included lifestyle, surgical history, and prior experience with music or other mind–body strategies for self-regulation.

As fundamental to qualitative methodology,^72,73 the reported responses to questions were grouped into themes that were peer-tested with members of the research team before and during the coding process.

The Appendix shows the Spine Study: Data Collection Form that was used.

VAS, HADS, and TSK data were tabulated by blinded research assistants and analyzed by a statistician. Patients were identified by number assignment, and their data and personal information were kept confidentially stored.

Statistical Methods

Means and standard deviations were used for continuous variables, and frequencies (percentages) for categorical variables. All outcomes were analyzed on an intent-to-treat basis. Repeated-measures analysis of variance was used to compare changes in outcomes from before to after intervention for the music and control groups. In particular, a statistically significant Group (music vs control) × Time (before vs after intervention) interaction would support the hypothesis that there would be more benefit (less pain) in the music group as a result of the music therapy. For all tests, significance was set at P < .05. SPSS Version 20 (IBM) was used for all statistical analyses. Based on previously found differences in heart rate and mobility,³¹ we assumed an effect size of 0.71 for the difference between music and control (no music), which would require 32 patients per group to achieve a power of 0.8 with an α of 0.05.

Results

Of the 136 patients who were asked to participate in the study, 76 were not enrolled; the other 60 were equally assigned to either the control group or the music therapy group (n = 30 in each) according to randomization indicated by a blinded statistician (Figure 1).

All outcomes were measured before and after intervention. Table 1 summarizes the demographic and clinical characteristics of the control and music therapy patients.

There were no statistically significant clinical differences between the groups in terms of any demographic or clinical characteristic. Mean age was 48 years for the control group and 49 years for the music group (P = .58). Sixty-seven percent of control patients and 50% of music patients were female (P = .24). Baseline perspectives with regard to the outcome of their surgery are also included (Ps > .05).

Table 2 lists the pre-intervention and post-intervention comparisons of the main outcomes between groups.

The groups showed significant differences in degree and direction of change in VAS pain ratings (P = .01). VAS pain levels increased slightly in the control group (to 5.87 from 5.20) but decreased by more than 1 point in the music group (to 5.09 from 6.20) (Figure 2).

The control and music groups did not differ in the rate of change in scores on HADS Anxiety (P = .62), HADS Depression (P = .85), or TSK (P = .93). Both groups had slight increases in HADS Anxiety, comparable decreases in HADS Depression, and minimal changes in TSK.

The emerging themes of the responses are listed in Tables 3 and 4 and are explained here:

Relationship with music was coded for significance and included reports of music as a resource accessed for stimulation and/or relaxation through listening; direct involvement with instrument playing; and history of music training. 

This area was left broad because we think any of the listed criteria would define music as an inner resource for enhanced coping.

Perceptions of surgical outcome in patients’ responses were coded across 3 themes: (1) optimistic (belief and hope in returning to original baseline of functionality), (2) indifferent (neither hopeful nor cynical about results of surgery), and (3) pessimistic (belief that nothing will restore the quality of life that existed before the spinal condition).

The CAS helped us better understand the diversity and complexity of the pain experience.

With use of this nonverbal form of expression, patients’ reports of postoperative pain often included pain that otherwise had been perceived by patients as unrelated and therefore underreported.

 

Discussion

Our hospital has the unique capability of providing music therapy to postoperative and other hospitalized patients. In this study, we compared the impact of a structured postoperative music therapy program on spine patients relative to control patients who did not receive music therapy after spine surgery.

We found a significant benefit in VAS pain levels (>1 point) but no statistically significant differences in HADS Anxiety, HADS Depression, or TSK scores. Although a 2-point difference is usually considered clinically significant, the degree of change in the music group is notable for having been achieved by nonpharmacologic means with scant chance of adverse effects. We suspect the lack of significant change in HADS Anxiety, HADS Depression, and TSK scores is attributable to the narrow study window. Given the observational data from our pilot study⁵⁸ and ongoing results with spine patients,³² it seems clear that both mood state and resilience in coping are enhanced through an ongoing relationship with music therapy.

The study of a population as vulnerable as patients recovering from spine surgery raises many issues for providers and researchers. Although it is worthwhile to determine the efficacy of integrative modalities in serving these patients, the request for participation in a protocol at such a vulnerable time was often resisted. During our pilot work, it became clear that the ability of potential subjects to comprehend and complete protocol surveys was impacted by adverse effects, including sedation drowsiness; respiratory depression; nausea and vomiting; pruritus; and urinary retention caused by the medications used for postoperative pain management. Consequently, after piloting 5 cases before the main study, we extended the enrollment window to 72 hours.

Other unforeseen intrinsic or external obstacles were identified: Patient-related issues—including availability, level of interest in participation, and inability to participate because of the medication adverse effects mentioned.

Staff investment/education—addressed over the first 3 study years with several in-services, starting with the surgical team and continuing with nursing and support staff in various combinations. These meetings led to the creation of an Institutional Review Board (IRB) approved educational sheet for inclusion in the information packet given to surgical patients on registration.

Programming interruptions—caused by the convergence of several unanticipated factors, including a delay in expedited review of the IRB renewal during the year of Hurricane Sandy and an interruption in the spine team’s service for administrative and program modification.

Conclusion

Music therapy interventions (eg, use of patient-preferred live music) offered within a therapeutic relationship favorably affected pain perceptions in patients recovering from spine surgery. This effect was achieved through several therapeutic entry points, including support of expression and opportunities for emotional catharsis.

At the core of music therapy’s efficacy is individualized treatment, through which patients are supported in their recovery of “self.” Measurable benefits—including increased comfort; reduced pain; improved gait; increased range of motion, endurance, and ability to relax; and empowerment to actively participate in one’s own care through daily activities imbued with an enhanced sense of agency—are of cardinal importance, as they may lead to quicker recovery perceptions and enhanced quality of life.

Am J Orthop. 2017;46(1):E13-E22. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Music therapists use patient-preferred live music, increasing neurologic cues that enhance movement—a seminal recovery function in postoperative spine patients.
• Music therapy is an evidence-based, integrative treatment addressing body, mind, and spirit.
• Tension release through music therapy can serve as a critical mechanism for building resilience related to pain management.
• Music therapy and music medicine are distinct forms of clinical practice that focus on mind-body integration in the healing process.
• Music therapists, board-certified and licensed by the state as recognized healthcare professionals, address pain management, which is an increasing subspecialty in postoperative care.

About 70% of people in the United States experience at least 1 episode of back pain in their lifetime,¹ and more than 5 million are temporarily or permanently disabled by spinal disorders.^2-4 Some require surgery, which may rectify injury, but pain during recovery is often inevitable, and the road to recovery is not guaranteed to be smooth.^5-20

Postoperative spine patients are at major risk for pain management challenges.^14,15,18,20 Treatment is primarily pharmacologic and based on the surgical team’s pain management orders. Nursing care consists of monitoring the airway, vital signs, and neurovascular status and having patients rate their pain on a visual analog scale (VAS; 0 = no pain, 10 = worst pain imaginable). Nurses have the challenge of monitoring and continually assessing to make sure patients are achieving the optimal outcomes, particularly during the immediate postoperative period, when pain and anxiety are prominently increased.

Variability in spine surgery outcomes can be explained at least partly on the basis of prognostic psychological factors, including hypochondriasis, hysteria, depression, and poor pain coping strategies (eg, catastrophizing).²¹ In spine surgery patients, kinesiophobia (fear of moving) is a common component of distress that can impede recuperation.^21-23Psychological interventions that assist with the secondary stressors associated with pain and loss during physical recuperation are recommended, with increased attention given to the importance of treating the whole person: body, mind, and spirit.^24-29 Conventional pain-alleviating medical interventions can be enhanced with integrative therapies that empower patients to marshal their inner resources during recovery.^25-28Music therapy may be particularly suited to this effort, as it is adaptable to the patient’s individual and culturally specific needs.^29-33

Rationale for Live Music

Pain is subjective and personal, and warrants an individualized approach to care. There is a body of music medicine research on the use of recorded music in modulating psychological and physiological factors in pain perception.^30,32,34-54 This research supports the unique relationship of music to well-being, and the understanding that controlling any of these factors affects the duration, intensity, and quality of that experience.^41,43,52

These findings provide incentive for breathing-entrained music therapy interventions, which enhance the relaxation response and release of pain-related tension;^32,55-58 empower patients to unlock physical and emotional tension;^32,57,58 provide a channel for expression and body movement; and enhance blood flow and/or alleviate pain by activating neurologic areas involved in the experience of pain.^59-62Studies have found that physical endurance may be enhanced when movement is rhythmically coordinated with a musical stimulus.^63-66 Music may prolong physical endurance by inhibiting psychological feedback associated with physical exertion related to fatigue, which may translate into accelerated recovery periods. When we listen to a rhythmic sound, our brains tend to automatically synchronize, or entrain, to external rhythmic cues that can stimulate increased motor control and coordination.⁶³ Sound can arouse and raise the excitability of spinal motor neurons mediated by auditory-motor neuronal connections on the brain stem and spinal cord level.^64-66 Rhythmically organized sounds serve as a neurological function in our capacity to organize predictable timing cues that are apparent in music, and may result in an effective treatment intervention in recovery.^63,64

Music Therapy in Recovery From Spine Surgery

In music therapy, music is used within a therapeutic relationship to support or affect change in the patient and the treatment regimen.^32,33,56-58 Research on music therapy with patients who are recovering from spine surgery is scant.^67-69 Kleiber and Adamek⁶⁷ studied perceptions of music therapy in 8 adolescents after spinal fusion surgery. In their study, a music therapist provided patients with a postoperative music therapy session focusing on the use of patient-preferred live music for relaxation and expression. Although their qualitative query was based on a therapeutic approach similar to that used in the present study, only 1 session was offered during the recovery period, and follow-up was conducted by survey invitation and telephone. In addition, the number of participants was small, and there was no quantitative measure of pain or other symptoms.

 

Another study focused on the effects of listening to music on pain intensity and distress after spine surgery.⁶⁸ Patients in the study’s music group made their selections from prerecorded classical music and domestic and international popular songs from various genres and listened to their chosen recordings 30 minutes a day. Although the study was not a music therapy study per se, it showed a positive impact of listening to music on anxiety and pain perception in 60 adults who were randomly assigned to the music group or to a non-music control group (n = 30 in each). Differences between the music and control groups’ VAS ratings of anxiety (Ps = .018-.001) and pain (P = .001) were statistically significant.

Different from our study, the aforementioned studies did not include tension release–focused live music offered within a therapeutic relationship. Our 1.5-year pilot study, conducted prior to the present study indicated that music therapy led to increased resilience and recovery mechanisms.⁵⁸

Methods

Our mixed-methods study design combined standard medical treatment with integrative music therapy interventions based on pain assessments to better understand the effects of music therapy on the recovery of patients after spine surgery.

The Spine Institute of New York within the Department of Orthopedic Surgery at Mount Sinai Beth Israel provides surgical treatment of common spinal cord conditions. Prioritizing patient satisfaction and positive outcomes,^27,28 the institute integrates music therapy through the Louis Armstrong Center for Music and Medicine to enhance treatment of pain symptoms.

Patients were recruited by the research team as per the daily surgical schedule, or through referral by the medical team or patient care navigator. Sixty patients (35 female, 25 male) ranging in age from 40 to 55 years underwent anterior, posterior, or anterior-posterior spinal fusion and were enrolled in the study after signing a participation consent form. Minorities, women, and patients with Medicaid and Medicare were included. Patients who received a diagnosis of clinical psychosis or depression prior to spine injury were excluded.

The experimental group received music therapy plus standard care (medical and nursing care with scheduled pharmacologic pain intervention), and a wait-listed control group received standard care only. A randomization chart created by a blinded statistician who did not have access to the patient census determined the intervention–nonintervention schedule. Patients in the music therapy group received one 30-minute music therapy session during an 8-hour period within 72 hours after surgery.

For both groups, measurements were completed before and after the study window. Control patients were offered music therapy after completion of the post-intervention surveys in order to minimize the ethical dilemma of denying potentially helpful pain intervention. For this same reason, both groups were given the option of receiving follow-up music therapy sessions for the duration of their hospitalization.

The research team consisted of 2 licensed, board-certified music therapists. In addition, Master’s-level music therapy interns completing clinical hours as part of the trajectory for board certification served on the research team over the 5-year period 2009 to 2014, and 13 blinded research assistants helped with enrolling and collecting data on patients.

Intervention

Each music therapy session included a warm-up phase of verbal or musical discourse. Next was the treatment phase, which was based on patient need as assessed during warm-up. Treatment options included use of patient-preferred live music that supported tension release/relaxation through incentive-based clinical improvisation, singing, and/or rhythmic drumming or through breathwork and visualization. Psychoeducation about mind–body awareness through the use of breath and imagery was introduced and explained by the therapist at this time.

The improvised music intervention was focused on making salient the natural harmonic tension-resolution cycles that occur in music and that were entrained to the patient’s presentation (respiratory rate, verbal report, clinical presentation). When patient-preferred precomposed songs were used, tension resolution was achieved by sustaining cadence and resolution, also entrained to the patient’s respiratory cycles.^32,57,58

After the music therapy intervention, a period of closure or integration was facilitated by the therapist contingent on the patient’s degree of alertness. If awake, the patient was supported in a reflexive process of thoughts, impressions, or issues that may have contributed to the overall experience. If the patient was asleep, the researcher returned within 30 minutes for post-intervention interviewing. Interview information was recorded in a qualitative post-participation survey. To prevent bias, researchers who were not the treating clinicians conducted the surveys.

Outcome Measures

Both primary and secondary outcome measures were collected before and after the intervention. The primary outcome measure was VAS pain ratings, and the secondary outcome measures were scores on the Hospital Anxiety and Depression Scale (HADS), the Tampa Scale for Kinesiophobia (TSK), and the Color Analysis Scale (CAS).

 

VAS. With the VAS, images are used to rate pain. The scale has points labeled 0 to 10 and corresponding faces representing progression in pain intensity. The scale is quickly rendered and can be interpreted according to the patient’s recovery phase at time of rendering.

HADS. The HADS⁷⁰ provides a specific baseline for anxiety and depression as an indicator of how the patient might fare during hospitalization (admission through recovery and discharge).

TSK. The TSK⁷¹ provides insight into the patient’s perception of fear-related movement, which is an important factor in this study because of the movement required for rehabilitation. We used a shortened version of the TSK to accommodate the sensitive threshold for pain tolerance and pharmacologic side effects commonly experienced by spine patients.

CAS. The CAS was developed at the Louis Armstrong Center for Music and Medicine to assess comorbidities and dynamic aspects of pain. Through a coloring exercise, patients illustrate their pain experience, which gives tangible form to the abstract experience of pain.

Coding

We collected patients’ demographic data, including age, sex, and diagnoses. Clinical indicators of the preoperative baseline included lifestyle, surgical history, and prior experience with music or other mind–body strategies for self-regulation.

As fundamental to qualitative methodology,^72,73 the reported responses to questions were grouped into themes that were peer-tested with members of the research team before and during the coding process.

The Appendix shows the Spine Study: Data Collection Form that was used.

VAS, HADS, and TSK data were tabulated by blinded research assistants and analyzed by a statistician. Patients were identified by number assignment, and their data and personal information were kept confidentially stored.

Statistical Methods

Means and standard deviations were used for continuous variables, and frequencies (percentages) for categorical variables. All outcomes were analyzed on an intent-to-treat basis. Repeated-measures analysis of variance was used to compare changes in outcomes from before to after intervention for the music and control groups. In particular, a statistically significant Group (music vs control) × Time (before vs after intervention) interaction would support the hypothesis that there would be more benefit (less pain) in the music group as a result of the music therapy. For all tests, significance was set at P < .05. SPSS Version 20 (IBM) was used for all statistical analyses. Based on previously found differences in heart rate and mobility,³¹ we assumed an effect size of 0.71 for the difference between music and control (no music), which would require 32 patients per group to achieve a power of 0.8 with an α of 0.05.

Results

Of the 136 patients who were asked to participate in the study, 76 were not enrolled; the other 60 were equally assigned to either the control group or the music therapy group (n = 30 in each) according to randomization indicated by a blinded statistician (Figure 1).

All outcomes were measured before and after intervention. Table 1 summarizes the demographic and clinical characteristics of the control and music therapy patients.

There were no statistically significant clinical differences between the groups in terms of any demographic or clinical characteristic. Mean age was 48 years for the control group and 49 years for the music group (P = .58). Sixty-seven percent of control patients and 50% of music patients were female (P = .24). Baseline perspectives with regard to the outcome of their surgery are also included (Ps > .05).

Table 2 lists the pre-intervention and post-intervention comparisons of the main outcomes between groups.

The groups showed significant differences in degree and direction of change in VAS pain ratings (P = .01). VAS pain levels increased slightly in the control group (to 5.87 from 5.20) but decreased by more than 1 point in the music group (to 5.09 from 6.20) (Figure 2).

The control and music groups did not differ in the rate of change in scores on HADS Anxiety (P = .62), HADS Depression (P = .85), or TSK (P = .93). Both groups had slight increases in HADS Anxiety, comparable decreases in HADS Depression, and minimal changes in TSK.

The emerging themes of the responses are listed in Tables 3 and 4 and are explained here:

Relationship with music was coded for significance and included reports of music as a resource accessed for stimulation and/or relaxation through listening; direct involvement with instrument playing; and history of music training. 

This area was left broad because we think any of the listed criteria would define music as an inner resource for enhanced coping.

Perceptions of surgical outcome in patients’ responses were coded across 3 themes: (1) optimistic (belief and hope in returning to original baseline of functionality), (2) indifferent (neither hopeful nor cynical about results of surgery), and (3) pessimistic (belief that nothing will restore the quality of life that existed before the spinal condition).

The CAS helped us better understand the diversity and complexity of the pain experience.

With use of this nonverbal form of expression, patients’ reports of postoperative pain often included pain that otherwise had been perceived by patients as unrelated and therefore underreported.

 

Discussion

Our hospital has the unique capability of providing music therapy to postoperative and other hospitalized patients. In this study, we compared the impact of a structured postoperative music therapy program on spine patients relative to control patients who did not receive music therapy after spine surgery.

We found a significant benefit in VAS pain levels (>1 point) but no statistically significant differences in HADS Anxiety, HADS Depression, or TSK scores. Although a 2-point difference is usually considered clinically significant, the degree of change in the music group is notable for having been achieved by nonpharmacologic means with scant chance of adverse effects. We suspect the lack of significant change in HADS Anxiety, HADS Depression, and TSK scores is attributable to the narrow study window. Given the observational data from our pilot study⁵⁸ and ongoing results with spine patients,³² it seems clear that both mood state and resilience in coping are enhanced through an ongoing relationship with music therapy.

The study of a population as vulnerable as patients recovering from spine surgery raises many issues for providers and researchers. Although it is worthwhile to determine the efficacy of integrative modalities in serving these patients, the request for participation in a protocol at such a vulnerable time was often resisted. During our pilot work, it became clear that the ability of potential subjects to comprehend and complete protocol surveys was impacted by adverse effects, including sedation drowsiness; respiratory depression; nausea and vomiting; pruritus; and urinary retention caused by the medications used for postoperative pain management. Consequently, after piloting 5 cases before the main study, we extended the enrollment window to 72 hours.

Other unforeseen intrinsic or external obstacles were identified: Patient-related issues—including availability, level of interest in participation, and inability to participate because of the medication adverse effects mentioned.

Staff investment/education—addressed over the first 3 study years with several in-services, starting with the surgical team and continuing with nursing and support staff in various combinations. These meetings led to the creation of an Institutional Review Board (IRB) approved educational sheet for inclusion in the information packet given to surgical patients on registration.

Programming interruptions—caused by the convergence of several unanticipated factors, including a delay in expedited review of the IRB renewal during the year of Hurricane Sandy and an interruption in the spine team’s service for administrative and program modification.

Conclusion

Music therapy interventions (eg, use of patient-preferred live music) offered within a therapeutic relationship favorably affected pain perceptions in patients recovering from spine surgery. This effect was achieved through several therapeutic entry points, including support of expression and opportunities for emotional catharsis.

At the core of music therapy’s efficacy is individualized treatment, through which patients are supported in their recovery of “self.” Measurable benefits—including increased comfort; reduced pain; improved gait; increased range of motion, endurance, and ability to relax; and empowerment to actively participate in one’s own care through daily activities imbued with an enhanced sense of agency—are of cardinal importance, as they may lead to quicker recovery perceptions and enhanced quality of life.

Am J Orthop. 2017;46(1):E13-E22. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Music therapists use patient-preferred live music, increasing neurologic cues that enhance movement—a seminal recovery function in postoperative spine patients.
• Music therapy is an evidence-based, integrative treatment addressing body, mind, and spirit.
• Tension release through music therapy can serve as a critical mechanism for building resilience related to pain management.
• Music therapy and music medicine are distinct forms of clinical practice that focus on mind-body integration in the healing process.
• Music therapists, board-certified and licensed by the state as recognized healthcare professionals, address pain management, which is an increasing subspecialty in postoperative care.

About 70% of people in the United States experience at least 1 episode of back pain in their lifetime,¹ and more than 5 million are temporarily or permanently disabled by spinal disorders.^2-4 Some require surgery, which may rectify injury, but pain during recovery is often inevitable, and the road to recovery is not guaranteed to be smooth.^5-20

Postoperative spine patients are at major risk for pain management challenges.^14,15,18,20 Treatment is primarily pharmacologic and based on the surgical team’s pain management orders. Nursing care consists of monitoring the airway, vital signs, and neurovascular status and having patients rate their pain on a visual analog scale (VAS; 0 = no pain, 10 = worst pain imaginable). Nurses have the challenge of monitoring and continually assessing to make sure patients are achieving the optimal outcomes, particularly during the immediate postoperative period, when pain and anxiety are prominently increased.

Variability in spine surgery outcomes can be explained at least partly on the basis of prognostic psychological factors, including hypochondriasis, hysteria, depression, and poor pain coping strategies (eg, catastrophizing).²¹ In spine surgery patients, kinesiophobia (fear of moving) is a common component of distress that can impede recuperation.^21-23Psychological interventions that assist with the secondary stressors associated with pain and loss during physical recuperation are recommended, with increased attention given to the importance of treating the whole person: body, mind, and spirit.^24-29 Conventional pain-alleviating medical interventions can be enhanced with integrative therapies that empower patients to marshal their inner resources during recovery.^25-28Music therapy may be particularly suited to this effort, as it is adaptable to the patient’s individual and culturally specific needs.^29-33

Rationale for Live Music

Pain is subjective and personal, and warrants an individualized approach to care. There is a body of music medicine research on the use of recorded music in modulating psychological and physiological factors in pain perception.^30,32,34-54 This research supports the unique relationship of music to well-being, and the understanding that controlling any of these factors affects the duration, intensity, and quality of that experience.^41,43,52

These findings provide incentive for breathing-entrained music therapy interventions, which enhance the relaxation response and release of pain-related tension;^32,55-58 empower patients to unlock physical and emotional tension;^32,57,58 provide a channel for expression and body movement; and enhance blood flow and/or alleviate pain by activating neurologic areas involved in the experience of pain.^59-62Studies have found that physical endurance may be enhanced when movement is rhythmically coordinated with a musical stimulus.^63-66 Music may prolong physical endurance by inhibiting psychological feedback associated with physical exertion related to fatigue, which may translate into accelerated recovery periods. When we listen to a rhythmic sound, our brains tend to automatically synchronize, or entrain, to external rhythmic cues that can stimulate increased motor control and coordination.⁶³ Sound can arouse and raise the excitability of spinal motor neurons mediated by auditory-motor neuronal connections on the brain stem and spinal cord level.^64-66 Rhythmically organized sounds serve as a neurological function in our capacity to organize predictable timing cues that are apparent in music, and may result in an effective treatment intervention in recovery.^63,64

Music Therapy in Recovery From Spine Surgery

In music therapy, music is used within a therapeutic relationship to support or affect change in the patient and the treatment regimen.^32,33,56-58 Research on music therapy with patients who are recovering from spine surgery is scant.^67-69 Kleiber and Adamek⁶⁷ studied perceptions of music therapy in 8 adolescents after spinal fusion surgery. In their study, a music therapist provided patients with a postoperative music therapy session focusing on the use of patient-preferred live music for relaxation and expression. Although their qualitative query was based on a therapeutic approach similar to that used in the present study, only 1 session was offered during the recovery period, and follow-up was conducted by survey invitation and telephone. In addition, the number of participants was small, and there was no quantitative measure of pain or other symptoms.

 

Another study focused on the effects of listening to music on pain intensity and distress after spine surgery.⁶⁸ Patients in the study’s music group made their selections from prerecorded classical music and domestic and international popular songs from various genres and listened to their chosen recordings 30 minutes a day. Although the study was not a music therapy study per se, it showed a positive impact of listening to music on anxiety and pain perception in 60 adults who were randomly assigned to the music group or to a non-music control group (n = 30 in each). Differences between the music and control groups’ VAS ratings of anxiety (Ps = .018-.001) and pain (P = .001) were statistically significant.

Different from our study, the aforementioned studies did not include tension release–focused live music offered within a therapeutic relationship. Our 1.5-year pilot study, conducted prior to the present study indicated that music therapy led to increased resilience and recovery mechanisms.⁵⁸

Methods

Our mixed-methods study design combined standard medical treatment with integrative music therapy interventions based on pain assessments to better understand the effects of music therapy on the recovery of patients after spine surgery.

The Spine Institute of New York within the Department of Orthopedic Surgery at Mount Sinai Beth Israel provides surgical treatment of common spinal cord conditions. Prioritizing patient satisfaction and positive outcomes,^27,28 the institute integrates music therapy through the Louis Armstrong Center for Music and Medicine to enhance treatment of pain symptoms.

Patients were recruited by the research team as per the daily surgical schedule, or through referral by the medical team or patient care navigator. Sixty patients (35 female, 25 male) ranging in age from 40 to 55 years underwent anterior, posterior, or anterior-posterior spinal fusion and were enrolled in the study after signing a participation consent form. Minorities, women, and patients with Medicaid and Medicare were included. Patients who received a diagnosis of clinical psychosis or depression prior to spine injury were excluded.

The experimental group received music therapy plus standard care (medical and nursing care with scheduled pharmacologic pain intervention), and a wait-listed control group received standard care only. A randomization chart created by a blinded statistician who did not have access to the patient census determined the intervention–nonintervention schedule. Patients in the music therapy group received one 30-minute music therapy session during an 8-hour period within 72 hours after surgery.

For both groups, measurements were completed before and after the study window. Control patients were offered music therapy after completion of the post-intervention surveys in order to minimize the ethical dilemma of denying potentially helpful pain intervention. For this same reason, both groups were given the option of receiving follow-up music therapy sessions for the duration of their hospitalization.

The research team consisted of 2 licensed, board-certified music therapists. In addition, Master’s-level music therapy interns completing clinical hours as part of the trajectory for board certification served on the research team over the 5-year period 2009 to 2014, and 13 blinded research assistants helped with enrolling and collecting data on patients.

Intervention

Each music therapy session included a warm-up phase of verbal or musical discourse. Next was the treatment phase, which was based on patient need as assessed during warm-up. Treatment options included use of patient-preferred live music that supported tension release/relaxation through incentive-based clinical improvisation, singing, and/or rhythmic drumming or through breathwork and visualization. Psychoeducation about mind–body awareness through the use of breath and imagery was introduced and explained by the therapist at this time.

The improvised music intervention was focused on making salient the natural harmonic tension-resolution cycles that occur in music and that were entrained to the patient’s presentation (respiratory rate, verbal report, clinical presentation). When patient-preferred precomposed songs were used, tension resolution was achieved by sustaining cadence and resolution, also entrained to the patient’s respiratory cycles.^32,57,58

After the music therapy intervention, a period of closure or integration was facilitated by the therapist contingent on the patient’s degree of alertness. If awake, the patient was supported in a reflexive process of thoughts, impressions, or issues that may have contributed to the overall experience. If the patient was asleep, the researcher returned within 30 minutes for post-intervention interviewing. Interview information was recorded in a qualitative post-participation survey. To prevent bias, researchers who were not the treating clinicians conducted the surveys.

Outcome Measures

Both primary and secondary outcome measures were collected before and after the intervention. The primary outcome measure was VAS pain ratings, and the secondary outcome measures were scores on the Hospital Anxiety and Depression Scale (HADS), the Tampa Scale for Kinesiophobia (TSK), and the Color Analysis Scale (CAS).

 

VAS. With the VAS, images are used to rate pain. The scale has points labeled 0 to 10 and corresponding faces representing progression in pain intensity. The scale is quickly rendered and can be interpreted according to the patient’s recovery phase at time of rendering.

HADS. The HADS⁷⁰ provides a specific baseline for anxiety and depression as an indicator of how the patient might fare during hospitalization (admission through recovery and discharge).

TSK. The TSK⁷¹ provides insight into the patient’s perception of fear-related movement, which is an important factor in this study because of the movement required for rehabilitation. We used a shortened version of the TSK to accommodate the sensitive threshold for pain tolerance and pharmacologic side effects commonly experienced by spine patients.

CAS. The CAS was developed at the Louis Armstrong Center for Music and Medicine to assess comorbidities and dynamic aspects of pain. Through a coloring exercise, patients illustrate their pain experience, which gives tangible form to the abstract experience of pain.

Coding

We collected patients’ demographic data, including age, sex, and diagnoses. Clinical indicators of the preoperative baseline included lifestyle, surgical history, and prior experience with music or other mind–body strategies for self-regulation.

As fundamental to qualitative methodology,^72,73 the reported responses to questions were grouped into themes that were peer-tested with members of the research team before and during the coding process.

The Appendix shows the Spine Study: Data Collection Form that was used.

VAS, HADS, and TSK data were tabulated by blinded research assistants and analyzed by a statistician. Patients were identified by number assignment, and their data and personal information were kept confidentially stored.

Statistical Methods

Means and standard deviations were used for continuous variables, and frequencies (percentages) for categorical variables. All outcomes were analyzed on an intent-to-treat basis. Repeated-measures analysis of variance was used to compare changes in outcomes from before to after intervention for the music and control groups. In particular, a statistically significant Group (music vs control) × Time (before vs after intervention) interaction would support the hypothesis that there would be more benefit (less pain) in the music group as a result of the music therapy. For all tests, significance was set at P < .05. SPSS Version 20 (IBM) was used for all statistical analyses. Based on previously found differences in heart rate and mobility,³¹ we assumed an effect size of 0.71 for the difference between music and control (no music), which would require 32 patients per group to achieve a power of 0.8 with an α of 0.05.

Results

Of the 136 patients who were asked to participate in the study, 76 were not enrolled; the other 60 were equally assigned to either the control group or the music therapy group (n = 30 in each) according to randomization indicated by a blinded statistician (Figure 1).

All outcomes were measured before and after intervention. Table 1 summarizes the demographic and clinical characteristics of the control and music therapy patients.

There were no statistically significant clinical differences between the groups in terms of any demographic or clinical characteristic. Mean age was 48 years for the control group and 49 years for the music group (P = .58). Sixty-seven percent of control patients and 50% of music patients were female (P = .24). Baseline perspectives with regard to the outcome of their surgery are also included (Ps > .05).

Table 2 lists the pre-intervention and post-intervention comparisons of the main outcomes between groups.

The groups showed significant differences in degree and direction of change in VAS pain ratings (P = .01). VAS pain levels increased slightly in the control group (to 5.87 from 5.20) but decreased by more than 1 point in the music group (to 5.09 from 6.20) (Figure 2).

The control and music groups did not differ in the rate of change in scores on HADS Anxiety (P = .62), HADS Depression (P = .85), or TSK (P = .93). Both groups had slight increases in HADS Anxiety, comparable decreases in HADS Depression, and minimal changes in TSK.

The emerging themes of the responses are listed in Tables 3 and 4 and are explained here:

Relationship with music was coded for significance and included reports of music as a resource accessed for stimulation and/or relaxation through listening; direct involvement with instrument playing; and history of music training. 

This area was left broad because we think any of the listed criteria would define music as an inner resource for enhanced coping.

Perceptions of surgical outcome in patients’ responses were coded across 3 themes: (1) optimistic (belief and hope in returning to original baseline of functionality), (2) indifferent (neither hopeful nor cynical about results of surgery), and (3) pessimistic (belief that nothing will restore the quality of life that existed before the spinal condition).

The CAS helped us better understand the diversity and complexity of the pain experience.

With use of this nonverbal form of expression, patients’ reports of postoperative pain often included pain that otherwise had been perceived by patients as unrelated and therefore underreported.

 

Discussion

Our hospital has the unique capability of providing music therapy to postoperative and other hospitalized patients. In this study, we compared the impact of a structured postoperative music therapy program on spine patients relative to control patients who did not receive music therapy after spine surgery.

We found a significant benefit in VAS pain levels (>1 point) but no statistically significant differences in HADS Anxiety, HADS Depression, or TSK scores. Although a 2-point difference is usually considered clinically significant, the degree of change in the music group is notable for having been achieved by nonpharmacologic means with scant chance of adverse effects. We suspect the lack of significant change in HADS Anxiety, HADS Depression, and TSK scores is attributable to the narrow study window. Given the observational data from our pilot study⁵⁸ and ongoing results with spine patients,³² it seems clear that both mood state and resilience in coping are enhanced through an ongoing relationship with music therapy.

The study of a population as vulnerable as patients recovering from spine surgery raises many issues for providers and researchers. Although it is worthwhile to determine the efficacy of integrative modalities in serving these patients, the request for participation in a protocol at such a vulnerable time was often resisted. During our pilot work, it became clear that the ability of potential subjects to comprehend and complete protocol surveys was impacted by adverse effects, including sedation drowsiness; respiratory depression; nausea and vomiting; pruritus; and urinary retention caused by the medications used for postoperative pain management. Consequently, after piloting 5 cases before the main study, we extended the enrollment window to 72 hours.

Other unforeseen intrinsic or external obstacles were identified: Patient-related issues—including availability, level of interest in participation, and inability to participate because of the medication adverse effects mentioned.

Staff investment/education—addressed over the first 3 study years with several in-services, starting with the surgical team and continuing with nursing and support staff in various combinations. These meetings led to the creation of an Institutional Review Board (IRB) approved educational sheet for inclusion in the information packet given to surgical patients on registration.

Programming interruptions—caused by the convergence of several unanticipated factors, including a delay in expedited review of the IRB renewal during the year of Hurricane Sandy and an interruption in the spine team’s service for administrative and program modification.

Conclusion

Music therapy interventions (eg, use of patient-preferred live music) offered within a therapeutic relationship favorably affected pain perceptions in patients recovering from spine surgery. This effect was achieved through several therapeutic entry points, including support of expression and opportunities for emotional catharsis.

At the core of music therapy’s efficacy is individualized treatment, through which patients are supported in their recovery of “self.” Measurable benefits—including increased comfort; reduced pain; improved gait; increased range of motion, endurance, and ability to relax; and empowerment to actively participate in one’s own care through daily activities imbued with an enhanced sense of agency—are of cardinal importance, as they may lead to quicker recovery perceptions and enhanced quality of life.

Am J Orthop. 2017;46(1):E13-E22. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

The spinal vacuum sign or vacuum phenomenon (VP) is the radiographic finding of an air-density linear radiolucency in the intervertebral disc or vertebral body. The result of a gaseous accumulation, it is often a diagnostic sign of disc degeneration as well as a rare sign of infection, Schmorl node formation, or osteonecrosis.^1,2 Although the VP was first described on plain radiographs, it is better seen on computed tomography (CT).³ Multiple studies have found a possible association between the VP and nonunion in diaphyseal fractures,⁴ ankylosing spondylitis,^5,6 and lumbar spinal fusion.⁷

To our knowledge, no one has studied whether the intervertebral VP resolves after posterolateral lumbar spinal fusion in adults with degenerative spinal pathology, and no one has investigated the association between the persistence of the intervertebral VP and pseudarthrosis after posterolateral spinal fusion.

We conducted a study to determine whether the VP resolves after posterolateral lumbar spinal fusion procedures and whether persistence of the VP after fusion surgery is indicative of pseudarthrosis.

Materials and Methods

After obtaining Institutional Review Board approval for this study, we retrospectively reviewed the medical records of patients who had degenerative spinal stenosis with instability and the intervertebral vacuum sign on preoperative digital lumbar spine CT scans and who underwent posterolateral lumbar spinal fusion with or without instrumentation. Study inclusion criteria were lumbar spine CT at minimum 6-month follow-up after spinal fusion and preoperative and postoperative lumbar spine radiographs. Exclusion criteria were any type of interbody fusion procedure (anterior, posterior, transforaminal, lateral) at a level with the VP, age under 21 years, follow-up of less than 6 months, and incomplete radiographic records. As this was a retrospective study, patient consent was not required.

CT was performed with a 16-, 64-, or 128-slice multidetector CT scanner with effective tube current set at 250 to 320 mA, voltage set at 120 to 140 kV, and pitch set at 0.75 to 0.9. After axial acquisition of 3×3-mm isometric voxels, sagittal and coronal multiplanar images were reconstructed with a slice thickness of 2 mm. Patient demographics, diagnoses, and surgical details were recorded. All digital lumbar spine CT scans and radiographs were initially screened on PACS (picture archiving and communication system) by the orthopedic spine surgery fellow at an academic medical institution; then they were reviewed on a radiology reading room monitor by 3 observers (senior radiologist, senior orthopedic spine surgeon, orthopedic spine surgery fellow). Axial images and sagittal and coronal reconstructed images of the preoperative and postoperative follow-up lumbar CT scans—together with the lateral and anteroposterior lumbar spine radiographs—were evaluated for the intervertebral VP. Mean (SD) follow-up (with CT to assess fusion) was 1.6 (0.86) years (range, 0.75-3.38 years). Fusion at each level was evaluated on the postoperative follow-up CT on axial images and sagittal and coronal reconstructed images; criteria for fusion were continuous bridging bone across posterolateral gutters and facets on one or both sides at each intervertebral level.⁸ Pseudarthrosis was recorded if there was no continuity of bridging bone across both posterolateral gutters and facets, a complete radiolucent line on both sides across a level, or lysis or loosening around screws. All recordings were made by consensus, or by majority decision in case of disagreement.

Presence of the VP at the lumbar levels not included in the fusion was also recorded on the preoperative and follow-up CT scan and radiographs.

Descriptive and inferential statistical tests were performed as applicable. Pearson χ² test and Fischer exact test were used to evaluate if there was a significant association between the groups where the VP disappeared and persisted and fusion and pseudarthrosis. Significance was set at P < .05. Statistical analysis was performed with Stata Version 10.0.

 

 

Results

Using the preoperative lumbar spine CT scans of 18 patients (10 men, 8 women), we identified 36 cases of intervertebral levels exhibiting the VP (median positive vacuum sign levels per patient, 2; minimum, 1; maximum, 5) at the levels included in the fusion (Table 1). Mean (SD) age at surgery was 67.6 (9.4) years (range, 46.5-79.6 years). Mean (SD) radiologic follow-up was 1.6 (0.86) years (range, 0.75-3.38 years). All patients underwent lumbar fusion with local autograft, allograft, and recombinant human bone morphogenetic protein 2. Spinal instrumentation was used in 16 of the 18 patients.

On preoperative CT, positive VP was diagnosed in the 36 cases as follows: L5–S1 (11 cases), L4–L5 (9 cases), L3–L4 (4 cases), L2–L3 (6 cases), L1–L2 (4 cases), and T12–L1 (2 cases). On follow-up CT, 15 cases showed persistence of the VP, and 21 cases showed disappearance of the VP (Table 1).

Evidence of spinal fusion was identified on follow-up CT in 32 (88.9%) of the 36 cases. In 3 of the 18 patients, nonunion was diagnosed. Of the 15 intervertebral cases in which the VP persisted, 13 (86.7%) showed evidence of fusion on CT, and 2 (13.3%) showed evidence of pseudarthrosis. Of the 21 intervertebral cases in which the VP disappeared, 19 (90.5%) showed evidence of fusion on CT, and 2 (9.5%) showed evidence of pseudarthrosis (Table 2). There was no significant difference in fusion rate or pseudarthrosis rate in the groups in which the VP persisted or disappeared (Fischer exact test, P = .99). There was no significant association between VP persistence or disappearance and sex, primary or revision surgery, or intervertebral level (Fischer exact test, P > .05). A case example is shown in the Figure.

 

At levels not included in spinal fusion, CT identified the VP at 6 lumbar intervertebral levels before surgery and 11 levels at follow-up. The VP did not disappear at any level not included in the fusion. At follow-up, no new VP was identified in a segment included in fusion. Results are summarized in Table 3.

Discussion

The association of radiologic intervertebral VP and disc degeneration, first recognized by Knutsson¹ in 1942, refers to the presence of gas, mainly containing nitrogen, in the crevices between or within vertebrae.² The VP is more often seen in patients older than 50 years, on plain radiographs in hyperextension.⁹ CT is more sensitive than radiography in detecting the VP; Lardé and colleagues³ found it in about 50% of 50 patients on CT scans but in only 12% of patients on radiographs. The VP is visible because of the nitrogen gas that accumulates when there is a negative pressure within the disc space. Nitrogen emerges from the blood and moves into the disc space; perhaps the disc space opens, causing the negative pressure.^1-3 On T1- or T2-weighted magnetic resonance imaging (MRI), the VP is visible as a signal void. MRI, however, is less accurate than CT.¹⁰ In a study of 10 patients who had low back pain and more than 1 level of intradiscal VP, and who underwent supine MRI examinations at 0, 1, and 2 hours, Wang and colleagues¹¹ found that, after prolonged supine positioning, the signal intensity of the vacuum was replaced by hyperintense fluid contents. D’Anastasi and colleagues,¹² in a study of 20 patients who had lumbar vacuum phenomenon on CT and underwent MRI examinations, found a significant correlation between presence of intradiscal fluid and amount of bone marrow edema on MRI and degenerative endplate abnormalities on CT. In the present study, we found that, after the spinal fusion vacuum phenomenon disappeared in 58.3% of the lumbar levels and persisted in 41.7% on follow-up CT at the levels included in posterolateral fusion, there were 5 new levels, adjacent to the lumbar fusion, where the VP was seen on the follow-up CT.

We studied whether evidence of a persistent vacuum sign on CT is indicative of pseudarthrosis. Other authors have reported an association between the VP and nonunion in fractures⁴ and ankylosing spondylitis.^5,6 In a study of 19 patients with diaphyseal fractures, Stallenberg and colleagues⁴ found that, in 7 of the 10 patients with nonunion, the VP was detected on CT at the nonunion site. Martel⁵ first reported on the intervertebral VP in a case of ankylosing spondylitis with spinal pseudarthrosis. Ten years later, in a study of 18 patients with advanced ankylosing spondylitis with spinal pseudarthrosis, Chan and colleagues⁶ identified the intervertebral VP on CT in 7 patients. Edwards and colleagues⁷ studied 15 patients with prior lumbar fusion with 17 positive intervertebral VP levels on CT and found that the vacuum disc sign was a strong predictor of lumbar nonunion as determined by surgical exploration. Mirovsky and colleagues¹³ identified the intravertebral vacuum cleft in 26 patients with an osteoporotic vertebral fracture treated with vertebroplasty and concluded that nonunion of the vertebral fracture could be identified by presence of the intravertebral vacuum cleft on radiography. In the present study, there was radiologic evidence of lumbar spinal fusion in 89% of disc levels with a preoperative positive intervertebral VP and pseudarthrosis in 11% of disc levels. The rate of fusion at levels with the VP was comparable to the rate at intervertebral levels without the phenomenon. These findings indicate that persistence of the VP after spinal fusion is not an indication that fusion has not been achieved. Preoperative VP also did not predispose to failure of fusion. That there is a persistent vacuum disc might imply that, even after successful fusion as seen on CT, some motion may be occurring at the disc level to cause a negative pressure phenomenon. Even in cases of facet fusion with bridging bone, there may still be motion at the disc level, as fusions can plastically deform (even with screws in), particularly in elderly osteopenic bone. We found no association between a persistent vacuum sign and pseudarthrosis. Our study findings are clinically useful even if the benefits are limited. These findings may help surgeons avoid misinterpreting this sign as an indication for additional surgery.

This study had some limitations. First, radiographs were used to determine presence or absence of fusion. Although CT is widely considered the gold standard for noninvasive assessment of fusion,¹⁴ even when both posterolateral gutters and facets have been found to be fused on CT, the probability of a solid fusion on exploration ranges from 69% to 96%.^8,15 Second, detection of the VP on radiographs and CT may be affected by patient position.¹¹ Third, this was a retrospective series with a small number of patients and limited follow-up with CT. Arthrodesis and the VP may take years to fully evolve. It is possible that fusion rates could be higher on longer follow-up, and resolution of the VP may occur with longer follow-up. Fourth, clinical outcomes were not evaluated, as there are other confounding factors, apart from successful fusion, that could affect clinical outcomes. A larger prospective controlled study would be helpful.

Conclusion

The radiologic intervertebral VP may persist after posterolateral lumbar spinal fusion. We did not find an association between the VP and pseudarthrosis. In addition, VP persistence on follow-up CT was not indicative of pseudarthrosis, and VP disappearance was not indicative of fusion. The vacuum sign should not be misinterpreted as an indication for additional surgery.

The spinal vacuum sign or vacuum phenomenon (VP) is the radiographic finding of an air-density linear radiolucency in the intervertebral disc or vertebral body. The result of a gaseous accumulation, it is often a diagnostic sign of disc degeneration as well as a rare sign of infection, Schmorl node formation, or osteonecrosis.^1,2 Although the VP was first described on plain radiographs, it is better seen on computed tomography (CT).³ Multiple studies have found a possible association between the VP and nonunion in diaphyseal fractures,⁴ ankylosing spondylitis,^5,6 and lumbar spinal fusion.⁷

To our knowledge, no one has studied whether the intervertebral VP resolves after posterolateral lumbar spinal fusion in adults with degenerative spinal pathology, and no one has investigated the association between the persistence of the intervertebral VP and pseudarthrosis after posterolateral spinal fusion.

We conducted a study to determine whether the VP resolves after posterolateral lumbar spinal fusion procedures and whether persistence of the VP after fusion surgery is indicative of pseudarthrosis.

Materials and Methods

After obtaining Institutional Review Board approval for this study, we retrospectively reviewed the medical records of patients who had degenerative spinal stenosis with instability and the intervertebral vacuum sign on preoperative digital lumbar spine CT scans and who underwent posterolateral lumbar spinal fusion with or without instrumentation. Study inclusion criteria were lumbar spine CT at minimum 6-month follow-up after spinal fusion and preoperative and postoperative lumbar spine radiographs. Exclusion criteria were any type of interbody fusion procedure (anterior, posterior, transforaminal, lateral) at a level with the VP, age under 21 years, follow-up of less than 6 months, and incomplete radiographic records. As this was a retrospective study, patient consent was not required.

CT was performed with a 16-, 64-, or 128-slice multidetector CT scanner with effective tube current set at 250 to 320 mA, voltage set at 120 to 140 kV, and pitch set at 0.75 to 0.9. After axial acquisition of 3×3-mm isometric voxels, sagittal and coronal multiplanar images were reconstructed with a slice thickness of 2 mm. Patient demographics, diagnoses, and surgical details were recorded. All digital lumbar spine CT scans and radiographs were initially screened on PACS (picture archiving and communication system) by the orthopedic spine surgery fellow at an academic medical institution; then they were reviewed on a radiology reading room monitor by 3 observers (senior radiologist, senior orthopedic spine surgeon, orthopedic spine surgery fellow). Axial images and sagittal and coronal reconstructed images of the preoperative and postoperative follow-up lumbar CT scans—together with the lateral and anteroposterior lumbar spine radiographs—were evaluated for the intervertebral VP. Mean (SD) follow-up (with CT to assess fusion) was 1.6 (0.86) years (range, 0.75-3.38 years). Fusion at each level was evaluated on the postoperative follow-up CT on axial images and sagittal and coronal reconstructed images; criteria for fusion were continuous bridging bone across posterolateral gutters and facets on one or both sides at each intervertebral level.⁸ Pseudarthrosis was recorded if there was no continuity of bridging bone across both posterolateral gutters and facets, a complete radiolucent line on both sides across a level, or lysis or loosening around screws. All recordings were made by consensus, or by majority decision in case of disagreement.

Presence of the VP at the lumbar levels not included in the fusion was also recorded on the preoperative and follow-up CT scan and radiographs.

Descriptive and inferential statistical tests were performed as applicable. Pearson χ² test and Fischer exact test were used to evaluate if there was a significant association between the groups where the VP disappeared and persisted and fusion and pseudarthrosis. Significance was set at P < .05. Statistical analysis was performed with Stata Version 10.0.

 

 

Results

Using the preoperative lumbar spine CT scans of 18 patients (10 men, 8 women), we identified 36 cases of intervertebral levels exhibiting the VP (median positive vacuum sign levels per patient, 2; minimum, 1; maximum, 5) at the levels included in the fusion (Table 1). Mean (SD) age at surgery was 67.6 (9.4) years (range, 46.5-79.6 years). Mean (SD) radiologic follow-up was 1.6 (0.86) years (range, 0.75-3.38 years). All patients underwent lumbar fusion with local autograft, allograft, and recombinant human bone morphogenetic protein 2. Spinal instrumentation was used in 16 of the 18 patients.

On preoperative CT, positive VP was diagnosed in the 36 cases as follows: L5–S1 (11 cases), L4–L5 (9 cases), L3–L4 (4 cases), L2–L3 (6 cases), L1–L2 (4 cases), and T12–L1 (2 cases). On follow-up CT, 15 cases showed persistence of the VP, and 21 cases showed disappearance of the VP (Table 1).

Evidence of spinal fusion was identified on follow-up CT in 32 (88.9%) of the 36 cases. In 3 of the 18 patients, nonunion was diagnosed. Of the 15 intervertebral cases in which the VP persisted, 13 (86.7%) showed evidence of fusion on CT, and 2 (13.3%) showed evidence of pseudarthrosis. Of the 21 intervertebral cases in which the VP disappeared, 19 (90.5%) showed evidence of fusion on CT, and 2 (9.5%) showed evidence of pseudarthrosis (Table 2). There was no significant difference in fusion rate or pseudarthrosis rate in the groups in which the VP persisted or disappeared (Fischer exact test, P = .99). There was no significant association between VP persistence or disappearance and sex, primary or revision surgery, or intervertebral level (Fischer exact test, P > .05). A case example is shown in the Figure.

 

At levels not included in spinal fusion, CT identified the VP at 6 lumbar intervertebral levels before surgery and 11 levels at follow-up. The VP did not disappear at any level not included in the fusion. At follow-up, no new VP was identified in a segment included in fusion. Results are summarized in Table 3.

Discussion

The association of radiologic intervertebral VP and disc degeneration, first recognized by Knutsson¹ in 1942, refers to the presence of gas, mainly containing nitrogen, in the crevices between or within vertebrae.² The VP is more often seen in patients older than 50 years, on plain radiographs in hyperextension.⁹ CT is more sensitive than radiography in detecting the VP; Lardé and colleagues³ found it in about 50% of 50 patients on CT scans but in only 12% of patients on radiographs. The VP is visible because of the nitrogen gas that accumulates when there is a negative pressure within the disc space. Nitrogen emerges from the blood and moves into the disc space; perhaps the disc space opens, causing the negative pressure.^1-3 On T1- or T2-weighted magnetic resonance imaging (MRI), the VP is visible as a signal void. MRI, however, is less accurate than CT.¹⁰ In a study of 10 patients who had low back pain and more than 1 level of intradiscal VP, and who underwent supine MRI examinations at 0, 1, and 2 hours, Wang and colleagues¹¹ found that, after prolonged supine positioning, the signal intensity of the vacuum was replaced by hyperintense fluid contents. D’Anastasi and colleagues,¹² in a study of 20 patients who had lumbar vacuum phenomenon on CT and underwent MRI examinations, found a significant correlation between presence of intradiscal fluid and amount of bone marrow edema on MRI and degenerative endplate abnormalities on CT. In the present study, we found that, after the spinal fusion vacuum phenomenon disappeared in 58.3% of the lumbar levels and persisted in 41.7% on follow-up CT at the levels included in posterolateral fusion, there were 5 new levels, adjacent to the lumbar fusion, where the VP was seen on the follow-up CT.

We studied whether evidence of a persistent vacuum sign on CT is indicative of pseudarthrosis. Other authors have reported an association between the VP and nonunion in fractures⁴ and ankylosing spondylitis.^5,6 In a study of 19 patients with diaphyseal fractures, Stallenberg and colleagues⁴ found that, in 7 of the 10 patients with nonunion, the VP was detected on CT at the nonunion site. Martel⁵ first reported on the intervertebral VP in a case of ankylosing spondylitis with spinal pseudarthrosis. Ten years later, in a study of 18 patients with advanced ankylosing spondylitis with spinal pseudarthrosis, Chan and colleagues⁶ identified the intervertebral VP on CT in 7 patients. Edwards and colleagues⁷ studied 15 patients with prior lumbar fusion with 17 positive intervertebral VP levels on CT and found that the vacuum disc sign was a strong predictor of lumbar nonunion as determined by surgical exploration. Mirovsky and colleagues¹³ identified the intravertebral vacuum cleft in 26 patients with an osteoporotic vertebral fracture treated with vertebroplasty and concluded that nonunion of the vertebral fracture could be identified by presence of the intravertebral vacuum cleft on radiography. In the present study, there was radiologic evidence of lumbar spinal fusion in 89% of disc levels with a preoperative positive intervertebral VP and pseudarthrosis in 11% of disc levels. The rate of fusion at levels with the VP was comparable to the rate at intervertebral levels without the phenomenon. These findings indicate that persistence of the VP after spinal fusion is not an indication that fusion has not been achieved. Preoperative VP also did not predispose to failure of fusion. That there is a persistent vacuum disc might imply that, even after successful fusion as seen on CT, some motion may be occurring at the disc level to cause a negative pressure phenomenon. Even in cases of facet fusion with bridging bone, there may still be motion at the disc level, as fusions can plastically deform (even with screws in), particularly in elderly osteopenic bone. We found no association between a persistent vacuum sign and pseudarthrosis. Our study findings are clinically useful even if the benefits are limited. These findings may help surgeons avoid misinterpreting this sign as an indication for additional surgery.

This study had some limitations. First, radiographs were used to determine presence or absence of fusion. Although CT is widely considered the gold standard for noninvasive assessment of fusion,¹⁴ even when both posterolateral gutters and facets have been found to be fused on CT, the probability of a solid fusion on exploration ranges from 69% to 96%.^8,15 Second, detection of the VP on radiographs and CT may be affected by patient position.¹¹ Third, this was a retrospective series with a small number of patients and limited follow-up with CT. Arthrodesis and the VP may take years to fully evolve. It is possible that fusion rates could be higher on longer follow-up, and resolution of the VP may occur with longer follow-up. Fourth, clinical outcomes were not evaluated, as there are other confounding factors, apart from successful fusion, that could affect clinical outcomes. A larger prospective controlled study would be helpful.

Conclusion

The radiologic intervertebral VP may persist after posterolateral lumbar spinal fusion. We did not find an association between the VP and pseudarthrosis. In addition, VP persistence on follow-up CT was not indicative of pseudarthrosis, and VP disappearance was not indicative of fusion. The vacuum sign should not be misinterpreted as an indication for additional surgery.

The spinal vacuum sign or vacuum phenomenon (VP) is the radiographic finding of an air-density linear radiolucency in the intervertebral disc or vertebral body. The result of a gaseous accumulation, it is often a diagnostic sign of disc degeneration as well as a rare sign of infection, Schmorl node formation, or osteonecrosis.^1,2 Although the VP was first described on plain radiographs, it is better seen on computed tomography (CT).³ Multiple studies have found a possible association between the VP and nonunion in diaphyseal fractures,⁴ ankylosing spondylitis,^5,6 and lumbar spinal fusion.⁷

To our knowledge, no one has studied whether the intervertebral VP resolves after posterolateral lumbar spinal fusion in adults with degenerative spinal pathology, and no one has investigated the association between the persistence of the intervertebral VP and pseudarthrosis after posterolateral spinal fusion.

We conducted a study to determine whether the VP resolves after posterolateral lumbar spinal fusion procedures and whether persistence of the VP after fusion surgery is indicative of pseudarthrosis.

Materials and Methods

After obtaining Institutional Review Board approval for this study, we retrospectively reviewed the medical records of patients who had degenerative spinal stenosis with instability and the intervertebral vacuum sign on preoperative digital lumbar spine CT scans and who underwent posterolateral lumbar spinal fusion with or without instrumentation. Study inclusion criteria were lumbar spine CT at minimum 6-month follow-up after spinal fusion and preoperative and postoperative lumbar spine radiographs. Exclusion criteria were any type of interbody fusion procedure (anterior, posterior, transforaminal, lateral) at a level with the VP, age under 21 years, follow-up of less than 6 months, and incomplete radiographic records. As this was a retrospective study, patient consent was not required.

CT was performed with a 16-, 64-, or 128-slice multidetector CT scanner with effective tube current set at 250 to 320 mA, voltage set at 120 to 140 kV, and pitch set at 0.75 to 0.9. After axial acquisition of 3×3-mm isometric voxels, sagittal and coronal multiplanar images were reconstructed with a slice thickness of 2 mm. Patient demographics, diagnoses, and surgical details were recorded. All digital lumbar spine CT scans and radiographs were initially screened on PACS (picture archiving and communication system) by the orthopedic spine surgery fellow at an academic medical institution; then they were reviewed on a radiology reading room monitor by 3 observers (senior radiologist, senior orthopedic spine surgeon, orthopedic spine surgery fellow). Axial images and sagittal and coronal reconstructed images of the preoperative and postoperative follow-up lumbar CT scans—together with the lateral and anteroposterior lumbar spine radiographs—were evaluated for the intervertebral VP. Mean (SD) follow-up (with CT to assess fusion) was 1.6 (0.86) years (range, 0.75-3.38 years). Fusion at each level was evaluated on the postoperative follow-up CT on axial images and sagittal and coronal reconstructed images; criteria for fusion were continuous bridging bone across posterolateral gutters and facets on one or both sides at each intervertebral level.⁸ Pseudarthrosis was recorded if there was no continuity of bridging bone across both posterolateral gutters and facets, a complete radiolucent line on both sides across a level, or lysis or loosening around screws. All recordings were made by consensus, or by majority decision in case of disagreement.

Presence of the VP at the lumbar levels not included in the fusion was also recorded on the preoperative and follow-up CT scan and radiographs.

Descriptive and inferential statistical tests were performed as applicable. Pearson χ² test and Fischer exact test were used to evaluate if there was a significant association between the groups where the VP disappeared and persisted and fusion and pseudarthrosis. Significance was set at P < .05. Statistical analysis was performed with Stata Version 10.0.

 

 

Results

Using the preoperative lumbar spine CT scans of 18 patients (10 men, 8 women), we identified 36 cases of intervertebral levels exhibiting the VP (median positive vacuum sign levels per patient, 2; minimum, 1; maximum, 5) at the levels included in the fusion (Table 1). Mean (SD) age at surgery was 67.6 (9.4) years (range, 46.5-79.6 years). Mean (SD) radiologic follow-up was 1.6 (0.86) years (range, 0.75-3.38 years). All patients underwent lumbar fusion with local autograft, allograft, and recombinant human bone morphogenetic protein 2. Spinal instrumentation was used in 16 of the 18 patients.

On preoperative CT, positive VP was diagnosed in the 36 cases as follows: L5–S1 (11 cases), L4–L5 (9 cases), L3–L4 (4 cases), L2–L3 (6 cases), L1–L2 (4 cases), and T12–L1 (2 cases). On follow-up CT, 15 cases showed persistence of the VP, and 21 cases showed disappearance of the VP (Table 1).

Evidence of spinal fusion was identified on follow-up CT in 32 (88.9%) of the 36 cases. In 3 of the 18 patients, nonunion was diagnosed. Of the 15 intervertebral cases in which the VP persisted, 13 (86.7%) showed evidence of fusion on CT, and 2 (13.3%) showed evidence of pseudarthrosis. Of the 21 intervertebral cases in which the VP disappeared, 19 (90.5%) showed evidence of fusion on CT, and 2 (9.5%) showed evidence of pseudarthrosis (Table 2). There was no significant difference in fusion rate or pseudarthrosis rate in the groups in which the VP persisted or disappeared (Fischer exact test, P = .99). There was no significant association between VP persistence or disappearance and sex, primary or revision surgery, or intervertebral level (Fischer exact test, P > .05). A case example is shown in the Figure.

 

At levels not included in spinal fusion, CT identified the VP at 6 lumbar intervertebral levels before surgery and 11 levels at follow-up. The VP did not disappear at any level not included in the fusion. At follow-up, no new VP was identified in a segment included in fusion. Results are summarized in Table 3.

Discussion

The association of radiologic intervertebral VP and disc degeneration, first recognized by Knutsson¹ in 1942, refers to the presence of gas, mainly containing nitrogen, in the crevices between or within vertebrae.² The VP is more often seen in patients older than 50 years, on plain radiographs in hyperextension.⁹ CT is more sensitive than radiography in detecting the VP; Lardé and colleagues³ found it in about 50% of 50 patients on CT scans but in only 12% of patients on radiographs. The VP is visible because of the nitrogen gas that accumulates when there is a negative pressure within the disc space. Nitrogen emerges from the blood and moves into the disc space; perhaps the disc space opens, causing the negative pressure.^1-3 On T1- or T2-weighted magnetic resonance imaging (MRI), the VP is visible as a signal void. MRI, however, is less accurate than CT.¹⁰ In a study of 10 patients who had low back pain and more than 1 level of intradiscal VP, and who underwent supine MRI examinations at 0, 1, and 2 hours, Wang and colleagues¹¹ found that, after prolonged supine positioning, the signal intensity of the vacuum was replaced by hyperintense fluid contents. D’Anastasi and colleagues,¹² in a study of 20 patients who had lumbar vacuum phenomenon on CT and underwent MRI examinations, found a significant correlation between presence of intradiscal fluid and amount of bone marrow edema on MRI and degenerative endplate abnormalities on CT. In the present study, we found that, after the spinal fusion vacuum phenomenon disappeared in 58.3% of the lumbar levels and persisted in 41.7% on follow-up CT at the levels included in posterolateral fusion, there were 5 new levels, adjacent to the lumbar fusion, where the VP was seen on the follow-up CT.

We studied whether evidence of a persistent vacuum sign on CT is indicative of pseudarthrosis. Other authors have reported an association between the VP and nonunion in fractures⁴ and ankylosing spondylitis.^5,6 In a study of 19 patients with diaphyseal fractures, Stallenberg and colleagues⁴ found that, in 7 of the 10 patients with nonunion, the VP was detected on CT at the nonunion site. Martel⁵ first reported on the intervertebral VP in a case of ankylosing spondylitis with spinal pseudarthrosis. Ten years later, in a study of 18 patients with advanced ankylosing spondylitis with spinal pseudarthrosis, Chan and colleagues⁶ identified the intervertebral VP on CT in 7 patients. Edwards and colleagues⁷ studied 15 patients with prior lumbar fusion with 17 positive intervertebral VP levels on CT and found that the vacuum disc sign was a strong predictor of lumbar nonunion as determined by surgical exploration. Mirovsky and colleagues¹³ identified the intravertebral vacuum cleft in 26 patients with an osteoporotic vertebral fracture treated with vertebroplasty and concluded that nonunion of the vertebral fracture could be identified by presence of the intravertebral vacuum cleft on radiography. In the present study, there was radiologic evidence of lumbar spinal fusion in 89% of disc levels with a preoperative positive intervertebral VP and pseudarthrosis in 11% of disc levels. The rate of fusion at levels with the VP was comparable to the rate at intervertebral levels without the phenomenon. These findings indicate that persistence of the VP after spinal fusion is not an indication that fusion has not been achieved. Preoperative VP also did not predispose to failure of fusion. That there is a persistent vacuum disc might imply that, even after successful fusion as seen on CT, some motion may be occurring at the disc level to cause a negative pressure phenomenon. Even in cases of facet fusion with bridging bone, there may still be motion at the disc level, as fusions can plastically deform (even with screws in), particularly in elderly osteopenic bone. We found no association between a persistent vacuum sign and pseudarthrosis. Our study findings are clinically useful even if the benefits are limited. These findings may help surgeons avoid misinterpreting this sign as an indication for additional surgery.

This study had some limitations. First, radiographs were used to determine presence or absence of fusion. Although CT is widely considered the gold standard for noninvasive assessment of fusion,¹⁴ even when both posterolateral gutters and facets have been found to be fused on CT, the probability of a solid fusion on exploration ranges from 69% to 96%.^8,15 Second, detection of the VP on radiographs and CT may be affected by patient position.¹¹ Third, this was a retrospective series with a small number of patients and limited follow-up with CT. Arthrodesis and the VP may take years to fully evolve. It is possible that fusion rates could be higher on longer follow-up, and resolution of the VP may occur with longer follow-up. Fourth, clinical outcomes were not evaluated, as there are other confounding factors, apart from successful fusion, that could affect clinical outcomes. A larger prospective controlled study would be helpful.

Conclusion

The radiologic intervertebral VP may persist after posterolateral lumbar spinal fusion. We did not find an association between the VP and pseudarthrosis. In addition, VP persistence on follow-up CT was not indicative of pseudarthrosis, and VP disappearance was not indicative of fusion. The vacuum sign should not be misinterpreted as an indication for additional surgery.

Lumbar radiculopathy is a common problem encountered by orthopedic surgeons, and typically presents with lower back or buttock pain radiating down the leg.¹ While the most common causes of lumbar radiculopathy are lumbar disc herniation and spinal stenosis, the differential diagnosis for lower extremity pain is broad and can be musculoskeletal, vascular, neurologic, or inflammatory in nature.^1,2 Differentiating between orthopedic, neurologic, and vascular causes of leg pain, such as peripheral artery disease (PAD), can sometimes be challenging. This is especially true in aortoiliac PAD, which can present with hip, buttock, and thigh pain. Dorsalis pedis pulses can be palpable due to collateral circulation. A careful history and physical examination is crucial to the correct diagnosis. The history should clearly document the nature of the pain, details of walking impairment, and the alleviating effects of standing still or positional changes. A complete neurovascular examination should include observations regarding the skin, hair, and nails, examination of dorsal pedis, popliteal, and femoral pulses in comparison to the contralateral side, and documentation of dural tension signs. Misdiagnoses can send the patient down a path of unnecessary tests, unindicated procedures, and ultimately, a delay in definitive diagnosis and treatment.¹

To our knowledge, this is the first report on a series of patients with thigh pain initially diagnosed as radiculopathy who underwent unproductive diagnostic tests and procedures, and ultimately were given delayed diagnoses of aortoiliac PAD. The patients provided written informed consent for print and electronic publication of these case reports.

Case 1

An 81-year-old woman with a medical history notable for hypertension, hyperlipidemia, and stroke initially presented to an outside orthopedic institution with complaints of several months of lower back and right hip, thigh, and leg pain when walking. She did not report any history of night pain, weakness, or numbness. Examination at the time was notable for painful back extension, 4/5 hip flexion strength on the right compared to 5/5 on the left, but symmetric reflexes and negative dural tension signs. X-rays showed multilevel degenerative disc disease of the lumbar spine, and magnetic resonance imaging (MRI) showed a small L3/4 disc protrusion causing impingement of the L4 nerve root.

A transforaminal epidural steroid injection at the L4 level was performed with minimal resolution of symptoms. Several months later, right-sided intra-articular facet injections were performed at the L4/5 and L5/S1 levels, again with minimal relief of symptoms. At this point, the patient was sent for further physical therapy.

Over a year after symptom onset, the patient presented to our institution and was evaluated by a vascular surgeon. Physical examination was notable for 1+ femoral artery and dorsal pedis pulses on the right side, compared to 2+ on the left. An aortoiliac duplex ultrasound showed severe significant stenosis of the right common iliac artery (>75%).

The patient underwent a right common iliac artery angioplasty and stenting (Figures 1A, 1B), which resolved her symptoms.

Case 2

A 65-year-old man, who is a former smoker with a medical history notable for hyperlipidemia and coronary artery disease status post myocardial infarction, presented with a long history of right leg pain. He underwent a L5/S1 anterior posterior fusion at an outside institution and did well for about 5 years after the procedure (Figures 2A, 2B). The pain returned and he underwent several years of physical therapy, epidural steroid injections, and implantation of a spinal cord stimulator with no improvement. He reported right leg pain with minimal back pain, primarily in the thigh and not radiating to the feet and toes. The pain limited him from walking more than 1 block. On examination, strength was 5/5 bilaterally. Pulse examination was notable for lack of dorsalis pedis/posterior tibial pulses bilaterally. He had no bowel or bladder dysfunction.

Computed tomography myelogram showed a moderate amount of stenosis at L3/4 and L4/5. He was sent for evaluation by a vascular surgeon. Arterial duplex ultrasound showed significant stenosis of the right common iliac artery.

Angioplasty was attempted but vascular surgery was unable to cross the lesion (Figures 3A, 3B), and the patient ultimately had a femoral-femoral bypass, which resolved his leg pain.

 

Case 3

A 78-year-old woman, nonsmoker, presented with a 1-year history of left buttock and thigh pain exacerbated by ambulation. Ambulation was limited to 2 blocks. The patient was being worked up for spinal and hip etiologies of pain at an outside hospital. MRI revealed a mild posterior disc herniation at L3/4 and L4/5 and moderate narrowing of the spinal canal. She underwent 2 epidural steroid injections with no improvement. The patient’s relative, a physician, suggested that the patient receive a vascular surgery consultation, and the patient ultimately presented to our institution for evaluation by vascular surgery.

The physical examination was significant for a 1+ dorsal pedis pulse on the left compared to 2+ on the right. Moreover, the patient only demonstrated trace L femoral pulse compared to the right. Strength was 5/5 bilaterally.

The patient was taken to the operating room for angioplasty and stenting of the left common iliac artery (Figures 4A, 4B). This provided immediate symptom relief, and she has remained asymptomatic.

Discussion

Lumbar radiculopathy is a common diagnosis encountered by orthopedic surgeons. Although the diagnosis can appear to be straightforward in a patient presenting with lower back and leg pain, the etiology of lower back and leg pain can be extremely varied, and can be musculoskeletal, neurologic, vascular, rheumatologic, or oncologic in origin.¹ In particular, differentiating between radiculopathy and vascular claudication can sometimes be challenging.

The 2 most common causes of lumbar radiculopathy are lumbar disc herniation and spinal stenosis.¹ Lumbar disc herniation results from tear in the annulus of the intervertebral disc, resulting in herniation of disc material into the spinal canal causing compression and irritation of spinal nerve roots.¹ Spinal stenosis is narrowing of the spinal canal that produces compression of neural elements before they exit the neural foramen.³ Adult degenerative spinal stenosis is most often caused by osteophytes from the facet joints or hypertrophy of the ligamentum flavum, and can be broadly categorized into central spinal stenosis or lateral spinal stenosis.

PAD is defined as progressive stenosis or occlusion, or aneurysmal dilation of noncoronary arteries.² When PAD affects the vessels of the lower extremities, the symptoms typically manifest as intermittent claudication, which is exercise-induced ischemic pain in the lower extremity that is relieved by rest.² As the disease progresses, symptoms can progress to rest pain, ulceration, and, eventually, gangrene. The most common cause of PAD is atherosclerosis, and the risk factors include smoking, hypertension, diabetes, and hyperlipidemia. The prevalence of PAD rises sharply with age, starting from <3% in ages less than 60 years to >20% in ages 75 years and older.⁴

A detailed and pertinent history from the patient provides important information for differentiating radiculopathy and neurogenic claudication from vascular claudication. Patients with lumbar radiculopathy typically report pain in the lower back radiating down the leg past the knee in a dermatomal distribution. The pain often begins soon if not immediately after activity, but often takes time for relief onset after rest. Positional changes in the back such as flexion can provide relief.² Patients with neurogenic claudication from central spinal stenosis can present with bilateral thigh pain from prolonged standing and activity that is alleviated with flexion or stooping.³ Patients may admit to a positive “shopping cart sign,” with increased walking comfort stooped forward with hands on a shopping cart.

In contrast, patients with vascular claudication often report pain in the calf, thigh, or hip, but rarely in the foot. The location of pain varies with area of stenosis; generally, patients with superficial femoral artery occlusion present with calf claudication, while patients with aortoiliac disease present with buttock and thigh pain. The pain typically occurs after a very reproducible length of walking, and is relieved by cessation of walking, often even if the patient remains standing. Back positioning should have no effect on the pain.^2-5

Physical examination should begin with observation of the patient’s gait and posture, which may be hunched over in the setting of spinal stenosis. Examination of the patient’s skin may show loss of hair, shiny skin, or atrophic changes suggestive of vascular disease (Figure 5).¹ Prior to proceeding to a spine examination, palpating the trochanteric bursa and testing for hip range of motion is important to rule out intra-articular hip pathology and trochanteric bursitis as common causes of pain in the area. Patients with radiculopathy may show sensory disturbances in a dermatomal distribution, muscular weakness at the corresponding spinal level, and decreased deep tendon reflexes. The straight leg raise test can elicit signs of nerve root tension. A careful examination of bilateral lower extremity pulses at the dorsal pedis, popliteal, and femoral levels can help identify any asymmetric or decreased pulses that would indicate peripheral vascular disease. With chronic aortoiliac disease, it is important to check for femoral pulses, given the dorsal pedis pulse can be present due to collateral circulation. And finally, the ankle brachial index (ABI), measured as the ratio of the systolic pressure at the ankle divided by the systolic pressure at the arm, is a good screening test for PAD.⁶ A normal ABI is >1.

A thorough history and physical examination can elicit important information that is helpful in evaluating orthopedic patients, especially to differentiate between spinal and vascular causes of leg pain. This can help avoid misdiagnoses, which result in unnecessary tests, procedures, and wasted time. Don’t forget the pulses!

Lumbar radiculopathy is a common problem encountered by orthopedic surgeons, and typically presents with lower back or buttock pain radiating down the leg.¹ While the most common causes of lumbar radiculopathy are lumbar disc herniation and spinal stenosis, the differential diagnosis for lower extremity pain is broad and can be musculoskeletal, vascular, neurologic, or inflammatory in nature.^1,2 Differentiating between orthopedic, neurologic, and vascular causes of leg pain, such as peripheral artery disease (PAD), can sometimes be challenging. This is especially true in aortoiliac PAD, which can present with hip, buttock, and thigh pain. Dorsalis pedis pulses can be palpable due to collateral circulation. A careful history and physical examination is crucial to the correct diagnosis. The history should clearly document the nature of the pain, details of walking impairment, and the alleviating effects of standing still or positional changes. A complete neurovascular examination should include observations regarding the skin, hair, and nails, examination of dorsal pedis, popliteal, and femoral pulses in comparison to the contralateral side, and documentation of dural tension signs. Misdiagnoses can send the patient down a path of unnecessary tests, unindicated procedures, and ultimately, a delay in definitive diagnosis and treatment.¹

To our knowledge, this is the first report on a series of patients with thigh pain initially diagnosed as radiculopathy who underwent unproductive diagnostic tests and procedures, and ultimately were given delayed diagnoses of aortoiliac PAD. The patients provided written informed consent for print and electronic publication of these case reports.

Case 1

An 81-year-old woman with a medical history notable for hypertension, hyperlipidemia, and stroke initially presented to an outside orthopedic institution with complaints of several months of lower back and right hip, thigh, and leg pain when walking. She did not report any history of night pain, weakness, or numbness. Examination at the time was notable for painful back extension, 4/5 hip flexion strength on the right compared to 5/5 on the left, but symmetric reflexes and negative dural tension signs. X-rays showed multilevel degenerative disc disease of the lumbar spine, and magnetic resonance imaging (MRI) showed a small L3/4 disc protrusion causing impingement of the L4 nerve root.

A transforaminal epidural steroid injection at the L4 level was performed with minimal resolution of symptoms. Several months later, right-sided intra-articular facet injections were performed at the L4/5 and L5/S1 levels, again with minimal relief of symptoms. At this point, the patient was sent for further physical therapy.

Over a year after symptom onset, the patient presented to our institution and was evaluated by a vascular surgeon. Physical examination was notable for 1+ femoral artery and dorsal pedis pulses on the right side, compared to 2+ on the left. An aortoiliac duplex ultrasound showed severe significant stenosis of the right common iliac artery (>75%).

The patient underwent a right common iliac artery angioplasty and stenting (Figures 1A, 1B), which resolved her symptoms.

Case 2

A 65-year-old man, who is a former smoker with a medical history notable for hyperlipidemia and coronary artery disease status post myocardial infarction, presented with a long history of right leg pain. He underwent a L5/S1 anterior posterior fusion at an outside institution and did well for about 5 years after the procedure (Figures 2A, 2B). The pain returned and he underwent several years of physical therapy, epidural steroid injections, and implantation of a spinal cord stimulator with no improvement. He reported right leg pain with minimal back pain, primarily in the thigh and not radiating to the feet and toes. The pain limited him from walking more than 1 block. On examination, strength was 5/5 bilaterally. Pulse examination was notable for lack of dorsalis pedis/posterior tibial pulses bilaterally. He had no bowel or bladder dysfunction.

Computed tomography myelogram showed a moderate amount of stenosis at L3/4 and L4/5. He was sent for evaluation by a vascular surgeon. Arterial duplex ultrasound showed significant stenosis of the right common iliac artery.

Angioplasty was attempted but vascular surgery was unable to cross the lesion (Figures 3A, 3B), and the patient ultimately had a femoral-femoral bypass, which resolved his leg pain.

 

Case 3

A 78-year-old woman, nonsmoker, presented with a 1-year history of left buttock and thigh pain exacerbated by ambulation. Ambulation was limited to 2 blocks. The patient was being worked up for spinal and hip etiologies of pain at an outside hospital. MRI revealed a mild posterior disc herniation at L3/4 and L4/5 and moderate narrowing of the spinal canal. She underwent 2 epidural steroid injections with no improvement. The patient’s relative, a physician, suggested that the patient receive a vascular surgery consultation, and the patient ultimately presented to our institution for evaluation by vascular surgery.

The physical examination was significant for a 1+ dorsal pedis pulse on the left compared to 2+ on the right. Moreover, the patient only demonstrated trace L femoral pulse compared to the right. Strength was 5/5 bilaterally.

The patient was taken to the operating room for angioplasty and stenting of the left common iliac artery (Figures 4A, 4B). This provided immediate symptom relief, and she has remained asymptomatic.

Discussion

Lumbar radiculopathy is a common diagnosis encountered by orthopedic surgeons. Although the diagnosis can appear to be straightforward in a patient presenting with lower back and leg pain, the etiology of lower back and leg pain can be extremely varied, and can be musculoskeletal, neurologic, vascular, rheumatologic, or oncologic in origin.¹ In particular, differentiating between radiculopathy and vascular claudication can sometimes be challenging.

The 2 most common causes of lumbar radiculopathy are lumbar disc herniation and spinal stenosis.¹ Lumbar disc herniation results from tear in the annulus of the intervertebral disc, resulting in herniation of disc material into the spinal canal causing compression and irritation of spinal nerve roots.¹ Spinal stenosis is narrowing of the spinal canal that produces compression of neural elements before they exit the neural foramen.³ Adult degenerative spinal stenosis is most often caused by osteophytes from the facet joints or hypertrophy of the ligamentum flavum, and can be broadly categorized into central spinal stenosis or lateral spinal stenosis.

PAD is defined as progressive stenosis or occlusion, or aneurysmal dilation of noncoronary arteries.² When PAD affects the vessels of the lower extremities, the symptoms typically manifest as intermittent claudication, which is exercise-induced ischemic pain in the lower extremity that is relieved by rest.² As the disease progresses, symptoms can progress to rest pain, ulceration, and, eventually, gangrene. The most common cause of PAD is atherosclerosis, and the risk factors include smoking, hypertension, diabetes, and hyperlipidemia. The prevalence of PAD rises sharply with age, starting from <3% in ages less than 60 years to >20% in ages 75 years and older.⁴

A detailed and pertinent history from the patient provides important information for differentiating radiculopathy and neurogenic claudication from vascular claudication. Patients with lumbar radiculopathy typically report pain in the lower back radiating down the leg past the knee in a dermatomal distribution. The pain often begins soon if not immediately after activity, but often takes time for relief onset after rest. Positional changes in the back such as flexion can provide relief.² Patients with neurogenic claudication from central spinal stenosis can present with bilateral thigh pain from prolonged standing and activity that is alleviated with flexion or stooping.³ Patients may admit to a positive “shopping cart sign,” with increased walking comfort stooped forward with hands on a shopping cart.

In contrast, patients with vascular claudication often report pain in the calf, thigh, or hip, but rarely in the foot. The location of pain varies with area of stenosis; generally, patients with superficial femoral artery occlusion present with calf claudication, while patients with aortoiliac disease present with buttock and thigh pain. The pain typically occurs after a very reproducible length of walking, and is relieved by cessation of walking, often even if the patient remains standing. Back positioning should have no effect on the pain.^2-5

Physical examination should begin with observation of the patient’s gait and posture, which may be hunched over in the setting of spinal stenosis. Examination of the patient’s skin may show loss of hair, shiny skin, or atrophic changes suggestive of vascular disease (Figure 5).¹ Prior to proceeding to a spine examination, palpating the trochanteric bursa and testing for hip range of motion is important to rule out intra-articular hip pathology and trochanteric bursitis as common causes of pain in the area. Patients with radiculopathy may show sensory disturbances in a dermatomal distribution, muscular weakness at the corresponding spinal level, and decreased deep tendon reflexes. The straight leg raise test can elicit signs of nerve root tension. A careful examination of bilateral lower extremity pulses at the dorsal pedis, popliteal, and femoral levels can help identify any asymmetric or decreased pulses that would indicate peripheral vascular disease. With chronic aortoiliac disease, it is important to check for femoral pulses, given the dorsal pedis pulse can be present due to collateral circulation. And finally, the ankle brachial index (ABI), measured as the ratio of the systolic pressure at the ankle divided by the systolic pressure at the arm, is a good screening test for PAD.⁶ A normal ABI is >1.

A thorough history and physical examination can elicit important information that is helpful in evaluating orthopedic patients, especially to differentiate between spinal and vascular causes of leg pain. This can help avoid misdiagnoses, which result in unnecessary tests, procedures, and wasted time. Don’t forget the pulses!

Lumbar radiculopathy is a common problem encountered by orthopedic surgeons, and typically presents with lower back or buttock pain radiating down the leg.¹ While the most common causes of lumbar radiculopathy are lumbar disc herniation and spinal stenosis, the differential diagnosis for lower extremity pain is broad and can be musculoskeletal, vascular, neurologic, or inflammatory in nature.^1,2 Differentiating between orthopedic, neurologic, and vascular causes of leg pain, such as peripheral artery disease (PAD), can sometimes be challenging. This is especially true in aortoiliac PAD, which can present with hip, buttock, and thigh pain. Dorsalis pedis pulses can be palpable due to collateral circulation. A careful history and physical examination is crucial to the correct diagnosis. The history should clearly document the nature of the pain, details of walking impairment, and the alleviating effects of standing still or positional changes. A complete neurovascular examination should include observations regarding the skin, hair, and nails, examination of dorsal pedis, popliteal, and femoral pulses in comparison to the contralateral side, and documentation of dural tension signs. Misdiagnoses can send the patient down a path of unnecessary tests, unindicated procedures, and ultimately, a delay in definitive diagnosis and treatment.¹

To our knowledge, this is the first report on a series of patients with thigh pain initially diagnosed as radiculopathy who underwent unproductive diagnostic tests and procedures, and ultimately were given delayed diagnoses of aortoiliac PAD. The patients provided written informed consent for print and electronic publication of these case reports.

Case 1

An 81-year-old woman with a medical history notable for hypertension, hyperlipidemia, and stroke initially presented to an outside orthopedic institution with complaints of several months of lower back and right hip, thigh, and leg pain when walking. She did not report any history of night pain, weakness, or numbness. Examination at the time was notable for painful back extension, 4/5 hip flexion strength on the right compared to 5/5 on the left, but symmetric reflexes and negative dural tension signs. X-rays showed multilevel degenerative disc disease of the lumbar spine, and magnetic resonance imaging (MRI) showed a small L3/4 disc protrusion causing impingement of the L4 nerve root.

A transforaminal epidural steroid injection at the L4 level was performed with minimal resolution of symptoms. Several months later, right-sided intra-articular facet injections were performed at the L4/5 and L5/S1 levels, again with minimal relief of symptoms. At this point, the patient was sent for further physical therapy.

Over a year after symptom onset, the patient presented to our institution and was evaluated by a vascular surgeon. Physical examination was notable for 1+ femoral artery and dorsal pedis pulses on the right side, compared to 2+ on the left. An aortoiliac duplex ultrasound showed severe significant stenosis of the right common iliac artery (>75%).

The patient underwent a right common iliac artery angioplasty and stenting (Figures 1A, 1B), which resolved her symptoms.

Case 2

A 65-year-old man, who is a former smoker with a medical history notable for hyperlipidemia and coronary artery disease status post myocardial infarction, presented with a long history of right leg pain. He underwent a L5/S1 anterior posterior fusion at an outside institution and did well for about 5 years after the procedure (Figures 2A, 2B). The pain returned and he underwent several years of physical therapy, epidural steroid injections, and implantation of a spinal cord stimulator with no improvement. He reported right leg pain with minimal back pain, primarily in the thigh and not radiating to the feet and toes. The pain limited him from walking more than 1 block. On examination, strength was 5/5 bilaterally. Pulse examination was notable for lack of dorsalis pedis/posterior tibial pulses bilaterally. He had no bowel or bladder dysfunction.

Computed tomography myelogram showed a moderate amount of stenosis at L3/4 and L4/5. He was sent for evaluation by a vascular surgeon. Arterial duplex ultrasound showed significant stenosis of the right common iliac artery.

Angioplasty was attempted but vascular surgery was unable to cross the lesion (Figures 3A, 3B), and the patient ultimately had a femoral-femoral bypass, which resolved his leg pain.

 

Case 3

A 78-year-old woman, nonsmoker, presented with a 1-year history of left buttock and thigh pain exacerbated by ambulation. Ambulation was limited to 2 blocks. The patient was being worked up for spinal and hip etiologies of pain at an outside hospital. MRI revealed a mild posterior disc herniation at L3/4 and L4/5 and moderate narrowing of the spinal canal. She underwent 2 epidural steroid injections with no improvement. The patient’s relative, a physician, suggested that the patient receive a vascular surgery consultation, and the patient ultimately presented to our institution for evaluation by vascular surgery.

The physical examination was significant for a 1+ dorsal pedis pulse on the left compared to 2+ on the right. Moreover, the patient only demonstrated trace L femoral pulse compared to the right. Strength was 5/5 bilaterally.

The patient was taken to the operating room for angioplasty and stenting of the left common iliac artery (Figures 4A, 4B). This provided immediate symptom relief, and she has remained asymptomatic.

Discussion

Lumbar radiculopathy is a common diagnosis encountered by orthopedic surgeons. Although the diagnosis can appear to be straightforward in a patient presenting with lower back and leg pain, the etiology of lower back and leg pain can be extremely varied, and can be musculoskeletal, neurologic, vascular, rheumatologic, or oncologic in origin.¹ In particular, differentiating between radiculopathy and vascular claudication can sometimes be challenging.

The 2 most common causes of lumbar radiculopathy are lumbar disc herniation and spinal stenosis.¹ Lumbar disc herniation results from tear in the annulus of the intervertebral disc, resulting in herniation of disc material into the spinal canal causing compression and irritation of spinal nerve roots.¹ Spinal stenosis is narrowing of the spinal canal that produces compression of neural elements before they exit the neural foramen.³ Adult degenerative spinal stenosis is most often caused by osteophytes from the facet joints or hypertrophy of the ligamentum flavum, and can be broadly categorized into central spinal stenosis or lateral spinal stenosis.

PAD is defined as progressive stenosis or occlusion, or aneurysmal dilation of noncoronary arteries.² When PAD affects the vessels of the lower extremities, the symptoms typically manifest as intermittent claudication, which is exercise-induced ischemic pain in the lower extremity that is relieved by rest.² As the disease progresses, symptoms can progress to rest pain, ulceration, and, eventually, gangrene. The most common cause of PAD is atherosclerosis, and the risk factors include smoking, hypertension, diabetes, and hyperlipidemia. The prevalence of PAD rises sharply with age, starting from <3% in ages less than 60 years to >20% in ages 75 years and older.⁴

A detailed and pertinent history from the patient provides important information for differentiating radiculopathy and neurogenic claudication from vascular claudication. Patients with lumbar radiculopathy typically report pain in the lower back radiating down the leg past the knee in a dermatomal distribution. The pain often begins soon if not immediately after activity, but often takes time for relief onset after rest. Positional changes in the back such as flexion can provide relief.² Patients with neurogenic claudication from central spinal stenosis can present with bilateral thigh pain from prolonged standing and activity that is alleviated with flexion or stooping.³ Patients may admit to a positive “shopping cart sign,” with increased walking comfort stooped forward with hands on a shopping cart.

In contrast, patients with vascular claudication often report pain in the calf, thigh, or hip, but rarely in the foot. The location of pain varies with area of stenosis; generally, patients with superficial femoral artery occlusion present with calf claudication, while patients with aortoiliac disease present with buttock and thigh pain. The pain typically occurs after a very reproducible length of walking, and is relieved by cessation of walking, often even if the patient remains standing. Back positioning should have no effect on the pain.^2-5

Physical examination should begin with observation of the patient’s gait and posture, which may be hunched over in the setting of spinal stenosis. Examination of the patient’s skin may show loss of hair, shiny skin, or atrophic changes suggestive of vascular disease (Figure 5).¹ Prior to proceeding to a spine examination, palpating the trochanteric bursa and testing for hip range of motion is important to rule out intra-articular hip pathology and trochanteric bursitis as common causes of pain in the area. Patients with radiculopathy may show sensory disturbances in a dermatomal distribution, muscular weakness at the corresponding spinal level, and decreased deep tendon reflexes. The straight leg raise test can elicit signs of nerve root tension. A careful examination of bilateral lower extremity pulses at the dorsal pedis, popliteal, and femoral levels can help identify any asymmetric or decreased pulses that would indicate peripheral vascular disease. With chronic aortoiliac disease, it is important to check for femoral pulses, given the dorsal pedis pulse can be present due to collateral circulation. And finally, the ankle brachial index (ABI), measured as the ratio of the systolic pressure at the ankle divided by the systolic pressure at the arm, is a good screening test for PAD.⁶ A normal ABI is >1.

A thorough history and physical examination can elicit important information that is helpful in evaluating orthopedic patients, especially to differentiate between spinal and vascular causes of leg pain. This can help avoid misdiagnoses, which result in unnecessary tests, procedures, and wasted time. Don’t forget the pulses!