Brian J. Cole, MD, MBA

ABSTRACT

Meniscus allograft transplantation (MAT) has yielded excellent long-term functional outcomes when performed in properly indicated patients. When evaluating a patient for potential MAT, it is imperative to evaluate past medical history and past surgical procedures. The ideal MAT candidate is a chronologically and physiologically young patient (<50 years) with symptomatic meniscal deficiency. Existing pathology in the knee needs to be carefully considered and issues such as malalignment, cartilage defects, and/or ligamentous instability may require a staged or concomitant procedure. Once an ideal candidate is identified, graft selection and preparation are critical steps to ensure a proper fit and long-term viability of the meniscus. When selecting the graft, accurate measurements must be taken, and this is most commonly performed using plain radiographs for this. Graft fixation can be accomplished by placing vertical mattress sutures and tying those down with the knee in full extension.

Continue to: Meniscus tears are common in the young, athletic patient population...

Meniscus tears are common in the young, athletic patient population. In the United States alone, approximately 700,000 meniscectomies are performed annually.¹ Given discouraging long-term clinical results following subtotal meniscectomy in young patients, meniscal repair is preferred whenever possible.² Despite short-term symptom relief if subtotal meniscectomy is required, some patients often go on to develop localized pain in the affected compartment, effusions, and eventual development of osteoarthritis. In such patients with symptomatic meniscal deficiency, meniscal allograft transplantation (MAT) has yielded excellent long-term functional outcomes.^3-5 Three recently published systematic reviews describe the outcomes of MAT in thousands of patients, noting positive outcomes in regard to pain and function for the majority of patients.^6-8 Specifically, in a review conducted by Elattar and colleagues⁷ consisting of 44 studies comprising 1136 grafts in 1068 patients, the authors reported clinical improvement in Lysholm Knee Scoring Scale score (44 to 77), visual analog scale (48 mm to 17 mm), and International Knee Documentation Committee (84% normal/nearly normal, 89% satisfaction), among other outcomes measures. Additionally, the complication (21.3%) and failure rates (10.6%) were considered acceptable by all authors. The purpose of this article is to review indications, operative preparation, critical aspects of surgical technique, and additional concomitant procedures commonly performed alongside MAT.

1. PATIENT SELECTION

When used with the proper indications, MAT offers improved functional outcomes and reduced pain for patients with symptomatic meniscal deficiency. When evaluating a patient for potential MAT, it is imperative to evaluate past medical history and past surgical procedures. The ideal MAT candidate is a chronologically and physiologically young patient (<50 years) with symptomatic meniscal deficiency who does not have (1) evidence of diffuse osteoarthritis (Outerbridge grade <2), including the absence of significant bony flattening or osteophytes in the involved compartment; (2) inflammatory arthritis; (3) active or previous joint infection; (4) mechanical axis malalignment; or (5) morbid obesity (Table). Long-leg weight-bearing anterior-posterior alignment radiographs are important in the work-up of any patient being considered for MAT, and consideration for concomitant or staged realignment high tibial osteotomy (HTO) or distal femoral osteotomy (DFO) should be given for patients in excessive varus or valgus, respectively. Although the decision to perform a realignment osteotomy is made on a patient-specific basis, if the weight-bearing line passes medial to the medial tibial spine or lateral to the lateral tibial spine, HTO or DFO, respectively, should be considered. Importantly, MAT is not typically recommended in the asymptomatic patient.⁹ Although some recent evidence suggests MAT may have chondroprotective effects on articular cartilage following meniscectomy, there is insufficient long-term outcome data to support the use of MAT as a prophylactic measure, especially given the fact that graft deterioration inevitably occurs at 7 to 10 years, with patients having to consider avoiding meniscus-dependent activities following transplant to protect their graft from traumatic failure.^10,11

Table. Summary of Indications and Contraindications for Meniscal Allograft Transplant (MAT)

^aContraindications for MAT are controversial, as the available literature discussing contraindications is very limited. This list is based on the experience of the senior author.

Long-term prospective studies have shown high graft survival and predominantly positive functional results after MAT. Age indications have expanded, with 1 recent study reporting 6% reoperation rate and zero failures in a cohort of 37 adolescent MAT patients.¹² High survival rates hold even among an athletic population, where rates of return to play after MAT have been reported to be >75% for those competing at a high school level or higher.¹³ In an active military population, <2% of patients progressed to revision MAT or total knee arthroplasty at minimum 2-year follow-up, but 22% of patients were unable to return to military duty owing to residual knee limitations.¹⁴ In this series, tobacco use correlated with failure, whereas MAT by high-volume, fellowship-trained orthopedic surgeons decreased rates of failure.

2. GRAFT SELECTION

In preparation for MAT, accurate measurements must be taken for appropriate size matching. Several measurement techniques have been described, including using plain radiographs, 3D computed tomography (CT), and magnetic resonance imaging (MRI).^15-18 There is limited data regarding the consequences of an improperly sized donor meniscus; however, an oversized lateral meniscus has been shown to increase the contact forces across the articular cartilage.¹⁹ Additionally, an undersized allograft may result in normal forces across the articular cartilage but greater forces across the meniscus.¹⁹

When sizing the recipient knee for MAT, accurate width and length measurements are critical. The most common technique used today includes measurements using anteroposterior and lateral radiographic images as described by Pollard and colleagues.¹⁵ The width of the meniscus is determined by the distance between 2 vertical lines perpendicular to the joint line, 1 of them tangential to the margin of the tibia metaphysis and the other between the medial and lateral tibial eminence in both knees (Figures 1A,1B). The length of the meniscus is measured on a lateral radiograph. A line is drawn at the level of the articular line between the anterior surface of the tibia above the tuberosity and a parallel line that is tangential to the posterior margin of the tibial plateau. Percent corrections are performed for these dimensions as described in previous publications.

Other techniques have been described to obtain accurate measurements of the recipient knee. For example, obtaining an MRI of the contralateral knee may provide a reproducible method of measuring both the width and length of the medial and lateral menisci.²⁰ CT has been used to measure the lateral meniscus independently, and it has been shown to exhibit less error in the measure of the tibial plateau when compared with X-rays.¹⁸ Both CT and MRI are more expensive than simple radiographs, and CT exposes the patient to an increased amount of radiation. Current evidence does not support standard use of these advanced imaging modalities for meniscal sizing.

Continue to: GRAFT PREPARATION AND PLACEMENT...

3. GRAFT PREPARATION AND PLACEMENT

At the time of surgery, the meniscus allograft is thawed in sterile saline and prepared on the back table. This can be done before or after the diagnostic arthroscopy and bone-slot preparation. Excess soft tissue surrounding the meniscal rim and/or anterior and posterior horns should be removed. Several techniques for MAT have been described, but we generally prefer a bridge-in-slot technique for both medial and lateral MAT.²¹ To prepare the meniscus allograft for a bridge-in-slot technique, the graft is cut with an oscillating saw to a width of 7 mm, with care taken to ensure that the bony insertions of both meniscal horns are preserved. Next, a transverse cut is made 10 mm below the meniscal horns to set the depth of the bone bridge. To assist with the sizing of the bone bridge, a rectangular sizing block and cutting jig is used (Figures 2A-2C). After marking the middle and posterior thirds of the meniscus, a No. 2 non-absorbable suture is placed at the junction of the posterior and middle thirds of the meniscus. This completes preparation of the allograft prior to implantation.

Attention is then turned to back the arthroscopy. A standard posteromedial (medial meniscus) or posterolateral (lateral meniscus) accessory incision is made, and a Henning retractor is carefully placed in order to receive the sutures that will be placed through the meniscus allograft via a standard inside-out repair technique. First, a zone-specific cannula is used to place a nitinol wire out the accessory incision. The looped end of the wire is pulled out of the anterior arthrotomy incision that will be used to shuttle the meniscus allograft into the joint. In order to pass the meniscal allograft into the joint, the passing suture previously placed through the meniscus is shuttled through the nitinol wire, and the wire is then pulled out the accessory incision, advancing the meniscus through the anteiror arthrotomy. As the meniscus is introduced, the traction suture is then gently tensioned to get the allograft completely into the joint. Next, the bone bridge is seated into the previously created bone slot, as the soft tissue component is manually pushed beneath the ipsilateral femoral condyle. Under direct visualization, the soft tissue component is reduced with a probe using firm, constant traction. To aid in reduction, it may be useful to apply compartment-specific varus or valgus stress and to cycle the knee once the meniscal complex is reduced.

4. GRAFT FIXATION

Once the graft has been passed completely into the joint, with the bone bridge seated into the bone slot, the long end of an Army-Navy retractor is placed firmly through the arthrotomy on the meniscal bone bridge, maintaining a downward force to allow the bridge to remain slotted. To lever down on the posterior aspect of the graft, a freer elevator is used from anterosuperior to posteroinferior. The bone bridge is then secured using a bioabsorbable interference screw, placed central to the bone bridge opposing the block to the ipsilateral compartment. The remainder of the meniscus is secured with an inside-out repair technique, working from posterior to anterior through a standard medial or lateral meniscal repair approach. In total, approximately 6 to 10 vertical mattress sutures are placed, and these can be placed both superiorly and inferiorly on the meniscus. Posteriorly, an all-inside suture repair device may be helpful. Finally, the anterior aspect of the meniscus is repaired to the capsule in an open fashion prior to closing the arthrotomy. Sutures are tied with the leg in extension. The meniscal repair incision is closed in a standard fashion using layers.

5. CONCOMITANT PATHOLOGY AND MAT

The presence of concomitant knee pathology in the context of meniscus deficiency is a challenging problem that requires careful attention to all aspects of the underlying condition of the knee. In cases where MAT is indicated, issues of malalignment, cartilage defects, and/or ligamentous instability may also need to be addressed either concomitantly or in staged fashion. For example, medial meniscal deficiency in the setting of varus alignment can be addressed with a concomitant HTO, whereas lateral meniscal deficiency in the setting of valgus malalignment can be addressed with a concomitant DFO. In both cases, the osteotomy corrects an abnormal mechanical axis, offloading the diseased compartment. This accomplishes 2 goals, namely to preserve the new MAT graft and to protect underlying articular cartilage.^22-24 The osteotomy is an important contributor to additional pain relief by offloading the compartment, and clinical studies have demonstrated that failure to address malalignment in the setting of surgical intervention for cartilage and meniscal insufficiency leads to inferior clinical outcomes and poor survival of transplanted tissue.^25-28

Continue to: In a meniscus-deficient patient with chondral lesions...

In a meniscus-deficient patient with chondral lesions (Outerbridge grade 3 or 4), concomitant MAT and cartilage restoration should be considered. Depending on the size and location of the chondral lesion, options include marrow stimulation, autologous chondrocyte implantation, osteochondral autograft transfer, as well as chondral and/or osteochondral allograft transplantation. In a systematic review of concomitant MAT and cartilage restoration procedures, Harris and colleagues²⁵ found that failure rates of the combined surgery were similar to those of either surgery in isolation.

Young athletes sustaining anterior cruciate ligament (ACL) tears commonly also have meniscal pathology that must be addressed. Most cases are treated with meniscal repair or partial meniscectomy, but occasionally patients present with ACL tear and symptomatic meniscal deficiency. Specifically, MAT survival relies largely on a knee with ligamentous stability, whereas outcomes of ACL reconstruction are improved with intact and functional menisci.²⁹ The surgical technique for MAT is modified slightly in the setting of performing a concomitant ACL reconstruction, with the ACL tibial tunnel drilled to avoid the meniscal bone slot if possible, followed by femoral tunnel creation. Femoral fixation of the ACL graft is accomplished after preparation of the meniscal slot. The meniscal graft is set into place (sutures are not yet tied), and tibial fixation of the ACL graft is performed next. We typically use an Achilles allograft for the ACL reconstruction, with the bone block used for femoral fixation to avoid bony impingement between the MAT bone bridge/block and the ACL graft. With the knee in full extension, the MAT sutures are tied at the conclusion of the surgical procedure. Concomitant MAT and ACL reconstruction has yielded positive long-term clinical outcomes, improved joint stability, and findings similar to historical results of ACL reconstruction or MAT performed in isolation.^30,31

CONCLUSION

When used with the proper indications, MAT has demonstrated the ability to restore function and reduce pain. Successful meniscal transplant requires attention to the patient’s past medical and surgical history. Similarly, care must be taken to address any concomitant knee pathology, such as coronal realignment, ligament reconstruction, or cartilage restoration.

ABSTRACT

Meniscus allograft transplantation (MAT) has yielded excellent long-term functional outcomes when performed in properly indicated patients. When evaluating a patient for potential MAT, it is imperative to evaluate past medical history and past surgical procedures. The ideal MAT candidate is a chronologically and physiologically young patient (<50 years) with symptomatic meniscal deficiency. Existing pathology in the knee needs to be carefully considered and issues such as malalignment, cartilage defects, and/or ligamentous instability may require a staged or concomitant procedure. Once an ideal candidate is identified, graft selection and preparation are critical steps to ensure a proper fit and long-term viability of the meniscus. When selecting the graft, accurate measurements must be taken, and this is most commonly performed using plain radiographs for this. Graft fixation can be accomplished by placing vertical mattress sutures and tying those down with the knee in full extension.

Continue to: Meniscus tears are common in the young, athletic patient population...

Meniscus tears are common in the young, athletic patient population. In the United States alone, approximately 700,000 meniscectomies are performed annually.¹ Given discouraging long-term clinical results following subtotal meniscectomy in young patients, meniscal repair is preferred whenever possible.² Despite short-term symptom relief if subtotal meniscectomy is required, some patients often go on to develop localized pain in the affected compartment, effusions, and eventual development of osteoarthritis. In such patients with symptomatic meniscal deficiency, meniscal allograft transplantation (MAT) has yielded excellent long-term functional outcomes.^3-5 Three recently published systematic reviews describe the outcomes of MAT in thousands of patients, noting positive outcomes in regard to pain and function for the majority of patients.^6-8 Specifically, in a review conducted by Elattar and colleagues⁷ consisting of 44 studies comprising 1136 grafts in 1068 patients, the authors reported clinical improvement in Lysholm Knee Scoring Scale score (44 to 77), visual analog scale (48 mm to 17 mm), and International Knee Documentation Committee (84% normal/nearly normal, 89% satisfaction), among other outcomes measures. Additionally, the complication (21.3%) and failure rates (10.6%) were considered acceptable by all authors. The purpose of this article is to review indications, operative preparation, critical aspects of surgical technique, and additional concomitant procedures commonly performed alongside MAT.

1. PATIENT SELECTION

When used with the proper indications, MAT offers improved functional outcomes and reduced pain for patients with symptomatic meniscal deficiency. When evaluating a patient for potential MAT, it is imperative to evaluate past medical history and past surgical procedures. The ideal MAT candidate is a chronologically and physiologically young patient (<50 years) with symptomatic meniscal deficiency who does not have (1) evidence of diffuse osteoarthritis (Outerbridge grade <2), including the absence of significant bony flattening or osteophytes in the involved compartment; (2) inflammatory arthritis; (3) active or previous joint infection; (4) mechanical axis malalignment; or (5) morbid obesity (Table). Long-leg weight-bearing anterior-posterior alignment radiographs are important in the work-up of any patient being considered for MAT, and consideration for concomitant or staged realignment high tibial osteotomy (HTO) or distal femoral osteotomy (DFO) should be given for patients in excessive varus or valgus, respectively. Although the decision to perform a realignment osteotomy is made on a patient-specific basis, if the weight-bearing line passes medial to the medial tibial spine or lateral to the lateral tibial spine, HTO or DFO, respectively, should be considered. Importantly, MAT is not typically recommended in the asymptomatic patient.⁹ Although some recent evidence suggests MAT may have chondroprotective effects on articular cartilage following meniscectomy, there is insufficient long-term outcome data to support the use of MAT as a prophylactic measure, especially given the fact that graft deterioration inevitably occurs at 7 to 10 years, with patients having to consider avoiding meniscus-dependent activities following transplant to protect their graft from traumatic failure.^10,11

Table. Summary of Indications and Contraindications for Meniscal Allograft Transplant (MAT)

^aContraindications for MAT are controversial, as the available literature discussing contraindications is very limited. This list is based on the experience of the senior author.

Long-term prospective studies have shown high graft survival and predominantly positive functional results after MAT. Age indications have expanded, with 1 recent study reporting 6% reoperation rate and zero failures in a cohort of 37 adolescent MAT patients.¹² High survival rates hold even among an athletic population, where rates of return to play after MAT have been reported to be >75% for those competing at a high school level or higher.¹³ In an active military population, <2% of patients progressed to revision MAT or total knee arthroplasty at minimum 2-year follow-up, but 22% of patients were unable to return to military duty owing to residual knee limitations.¹⁴ In this series, tobacco use correlated with failure, whereas MAT by high-volume, fellowship-trained orthopedic surgeons decreased rates of failure.

2. GRAFT SELECTION

In preparation for MAT, accurate measurements must be taken for appropriate size matching. Several measurement techniques have been described, including using plain radiographs, 3D computed tomography (CT), and magnetic resonance imaging (MRI).^15-18 There is limited data regarding the consequences of an improperly sized donor meniscus; however, an oversized lateral meniscus has been shown to increase the contact forces across the articular cartilage.¹⁹ Additionally, an undersized allograft may result in normal forces across the articular cartilage but greater forces across the meniscus.¹⁹

When sizing the recipient knee for MAT, accurate width and length measurements are critical. The most common technique used today includes measurements using anteroposterior and lateral radiographic images as described by Pollard and colleagues.¹⁵ The width of the meniscus is determined by the distance between 2 vertical lines perpendicular to the joint line, 1 of them tangential to the margin of the tibia metaphysis and the other between the medial and lateral tibial eminence in both knees (Figures 1A,1B). The length of the meniscus is measured on a lateral radiograph. A line is drawn at the level of the articular line between the anterior surface of the tibia above the tuberosity and a parallel line that is tangential to the posterior margin of the tibial plateau. Percent corrections are performed for these dimensions as described in previous publications.

Other techniques have been described to obtain accurate measurements of the recipient knee. For example, obtaining an MRI of the contralateral knee may provide a reproducible method of measuring both the width and length of the medial and lateral menisci.²⁰ CT has been used to measure the lateral meniscus independently, and it has been shown to exhibit less error in the measure of the tibial plateau when compared with X-rays.¹⁸ Both CT and MRI are more expensive than simple radiographs, and CT exposes the patient to an increased amount of radiation. Current evidence does not support standard use of these advanced imaging modalities for meniscal sizing.

Continue to: GRAFT PREPARATION AND PLACEMENT...

3. GRAFT PREPARATION AND PLACEMENT

At the time of surgery, the meniscus allograft is thawed in sterile saline and prepared on the back table. This can be done before or after the diagnostic arthroscopy and bone-slot preparation. Excess soft tissue surrounding the meniscal rim and/or anterior and posterior horns should be removed. Several techniques for MAT have been described, but we generally prefer a bridge-in-slot technique for both medial and lateral MAT.²¹ To prepare the meniscus allograft for a bridge-in-slot technique, the graft is cut with an oscillating saw to a width of 7 mm, with care taken to ensure that the bony insertions of both meniscal horns are preserved. Next, a transverse cut is made 10 mm below the meniscal horns to set the depth of the bone bridge. To assist with the sizing of the bone bridge, a rectangular sizing block and cutting jig is used (Figures 2A-2C). After marking the middle and posterior thirds of the meniscus, a No. 2 non-absorbable suture is placed at the junction of the posterior and middle thirds of the meniscus. This completes preparation of the allograft prior to implantation.

Attention is then turned to back the arthroscopy. A standard posteromedial (medial meniscus) or posterolateral (lateral meniscus) accessory incision is made, and a Henning retractor is carefully placed in order to receive the sutures that will be placed through the meniscus allograft via a standard inside-out repair technique. First, a zone-specific cannula is used to place a nitinol wire out the accessory incision. The looped end of the wire is pulled out of the anterior arthrotomy incision that will be used to shuttle the meniscus allograft into the joint. In order to pass the meniscal allograft into the joint, the passing suture previously placed through the meniscus is shuttled through the nitinol wire, and the wire is then pulled out the accessory incision, advancing the meniscus through the anteiror arthrotomy. As the meniscus is introduced, the traction suture is then gently tensioned to get the allograft completely into the joint. Next, the bone bridge is seated into the previously created bone slot, as the soft tissue component is manually pushed beneath the ipsilateral femoral condyle. Under direct visualization, the soft tissue component is reduced with a probe using firm, constant traction. To aid in reduction, it may be useful to apply compartment-specific varus or valgus stress and to cycle the knee once the meniscal complex is reduced.

4. GRAFT FIXATION

Once the graft has been passed completely into the joint, with the bone bridge seated into the bone slot, the long end of an Army-Navy retractor is placed firmly through the arthrotomy on the meniscal bone bridge, maintaining a downward force to allow the bridge to remain slotted. To lever down on the posterior aspect of the graft, a freer elevator is used from anterosuperior to posteroinferior. The bone bridge is then secured using a bioabsorbable interference screw, placed central to the bone bridge opposing the block to the ipsilateral compartment. The remainder of the meniscus is secured with an inside-out repair technique, working from posterior to anterior through a standard medial or lateral meniscal repair approach. In total, approximately 6 to 10 vertical mattress sutures are placed, and these can be placed both superiorly and inferiorly on the meniscus. Posteriorly, an all-inside suture repair device may be helpful. Finally, the anterior aspect of the meniscus is repaired to the capsule in an open fashion prior to closing the arthrotomy. Sutures are tied with the leg in extension. The meniscal repair incision is closed in a standard fashion using layers.

5. CONCOMITANT PATHOLOGY AND MAT

The presence of concomitant knee pathology in the context of meniscus deficiency is a challenging problem that requires careful attention to all aspects of the underlying condition of the knee. In cases where MAT is indicated, issues of malalignment, cartilage defects, and/or ligamentous instability may also need to be addressed either concomitantly or in staged fashion. For example, medial meniscal deficiency in the setting of varus alignment can be addressed with a concomitant HTO, whereas lateral meniscal deficiency in the setting of valgus malalignment can be addressed with a concomitant DFO. In both cases, the osteotomy corrects an abnormal mechanical axis, offloading the diseased compartment. This accomplishes 2 goals, namely to preserve the new MAT graft and to protect underlying articular cartilage.^22-24 The osteotomy is an important contributor to additional pain relief by offloading the compartment, and clinical studies have demonstrated that failure to address malalignment in the setting of surgical intervention for cartilage and meniscal insufficiency leads to inferior clinical outcomes and poor survival of transplanted tissue.^25-28

Continue to: In a meniscus-deficient patient with chondral lesions...

In a meniscus-deficient patient with chondral lesions (Outerbridge grade 3 or 4), concomitant MAT and cartilage restoration should be considered. Depending on the size and location of the chondral lesion, options include marrow stimulation, autologous chondrocyte implantation, osteochondral autograft transfer, as well as chondral and/or osteochondral allograft transplantation. In a systematic review of concomitant MAT and cartilage restoration procedures, Harris and colleagues²⁵ found that failure rates of the combined surgery were similar to those of either surgery in isolation.

Young athletes sustaining anterior cruciate ligament (ACL) tears commonly also have meniscal pathology that must be addressed. Most cases are treated with meniscal repair or partial meniscectomy, but occasionally patients present with ACL tear and symptomatic meniscal deficiency. Specifically, MAT survival relies largely on a knee with ligamentous stability, whereas outcomes of ACL reconstruction are improved with intact and functional menisci.²⁹ The surgical technique for MAT is modified slightly in the setting of performing a concomitant ACL reconstruction, with the ACL tibial tunnel drilled to avoid the meniscal bone slot if possible, followed by femoral tunnel creation. Femoral fixation of the ACL graft is accomplished after preparation of the meniscal slot. The meniscal graft is set into place (sutures are not yet tied), and tibial fixation of the ACL graft is performed next. We typically use an Achilles allograft for the ACL reconstruction, with the bone block used for femoral fixation to avoid bony impingement between the MAT bone bridge/block and the ACL graft. With the knee in full extension, the MAT sutures are tied at the conclusion of the surgical procedure. Concomitant MAT and ACL reconstruction has yielded positive long-term clinical outcomes, improved joint stability, and findings similar to historical results of ACL reconstruction or MAT performed in isolation.^30,31

CONCLUSION

When used with the proper indications, MAT has demonstrated the ability to restore function and reduce pain. Successful meniscal transplant requires attention to the patient’s past medical and surgical history. Similarly, care must be taken to address any concomitant knee pathology, such as coronal realignment, ligament reconstruction, or cartilage restoration.

ABSTRACT

Meniscus allograft transplantation (MAT) has yielded excellent long-term functional outcomes when performed in properly indicated patients. When evaluating a patient for potential MAT, it is imperative to evaluate past medical history and past surgical procedures. The ideal MAT candidate is a chronologically and physiologically young patient (<50 years) with symptomatic meniscal deficiency. Existing pathology in the knee needs to be carefully considered and issues such as malalignment, cartilage defects, and/or ligamentous instability may require a staged or concomitant procedure. Once an ideal candidate is identified, graft selection and preparation are critical steps to ensure a proper fit and long-term viability of the meniscus. When selecting the graft, accurate measurements must be taken, and this is most commonly performed using plain radiographs for this. Graft fixation can be accomplished by placing vertical mattress sutures and tying those down with the knee in full extension.

Continue to: Meniscus tears are common in the young, athletic patient population...

Meniscus tears are common in the young, athletic patient population. In the United States alone, approximately 700,000 meniscectomies are performed annually.¹ Given discouraging long-term clinical results following subtotal meniscectomy in young patients, meniscal repair is preferred whenever possible.² Despite short-term symptom relief if subtotal meniscectomy is required, some patients often go on to develop localized pain in the affected compartment, effusions, and eventual development of osteoarthritis. In such patients with symptomatic meniscal deficiency, meniscal allograft transplantation (MAT) has yielded excellent long-term functional outcomes.^3-5 Three recently published systematic reviews describe the outcomes of MAT in thousands of patients, noting positive outcomes in regard to pain and function for the majority of patients.^6-8 Specifically, in a review conducted by Elattar and colleagues⁷ consisting of 44 studies comprising 1136 grafts in 1068 patients, the authors reported clinical improvement in Lysholm Knee Scoring Scale score (44 to 77), visual analog scale (48 mm to 17 mm), and International Knee Documentation Committee (84% normal/nearly normal, 89% satisfaction), among other outcomes measures. Additionally, the complication (21.3%) and failure rates (10.6%) were considered acceptable by all authors. The purpose of this article is to review indications, operative preparation, critical aspects of surgical technique, and additional concomitant procedures commonly performed alongside MAT.

1. PATIENT SELECTION

When used with the proper indications, MAT offers improved functional outcomes and reduced pain for patients with symptomatic meniscal deficiency. When evaluating a patient for potential MAT, it is imperative to evaluate past medical history and past surgical procedures. The ideal MAT candidate is a chronologically and physiologically young patient (<50 years) with symptomatic meniscal deficiency who does not have (1) evidence of diffuse osteoarthritis (Outerbridge grade <2), including the absence of significant bony flattening or osteophytes in the involved compartment; (2) inflammatory arthritis; (3) active or previous joint infection; (4) mechanical axis malalignment; or (5) morbid obesity (Table). Long-leg weight-bearing anterior-posterior alignment radiographs are important in the work-up of any patient being considered for MAT, and consideration for concomitant or staged realignment high tibial osteotomy (HTO) or distal femoral osteotomy (DFO) should be given for patients in excessive varus or valgus, respectively. Although the decision to perform a realignment osteotomy is made on a patient-specific basis, if the weight-bearing line passes medial to the medial tibial spine or lateral to the lateral tibial spine, HTO or DFO, respectively, should be considered. Importantly, MAT is not typically recommended in the asymptomatic patient.⁹ Although some recent evidence suggests MAT may have chondroprotective effects on articular cartilage following meniscectomy, there is insufficient long-term outcome data to support the use of MAT as a prophylactic measure, especially given the fact that graft deterioration inevitably occurs at 7 to 10 years, with patients having to consider avoiding meniscus-dependent activities following transplant to protect their graft from traumatic failure.^10,11

Table. Summary of Indications and Contraindications for Meniscal Allograft Transplant (MAT)

^aContraindications for MAT are controversial, as the available literature discussing contraindications is very limited. This list is based on the experience of the senior author.

Long-term prospective studies have shown high graft survival and predominantly positive functional results after MAT. Age indications have expanded, with 1 recent study reporting 6% reoperation rate and zero failures in a cohort of 37 adolescent MAT patients.¹² High survival rates hold even among an athletic population, where rates of return to play after MAT have been reported to be >75% for those competing at a high school level or higher.¹³ In an active military population, <2% of patients progressed to revision MAT or total knee arthroplasty at minimum 2-year follow-up, but 22% of patients were unable to return to military duty owing to residual knee limitations.¹⁴ In this series, tobacco use correlated with failure, whereas MAT by high-volume, fellowship-trained orthopedic surgeons decreased rates of failure.

2. GRAFT SELECTION

In preparation for MAT, accurate measurements must be taken for appropriate size matching. Several measurement techniques have been described, including using plain radiographs, 3D computed tomography (CT), and magnetic resonance imaging (MRI).^15-18 There is limited data regarding the consequences of an improperly sized donor meniscus; however, an oversized lateral meniscus has been shown to increase the contact forces across the articular cartilage.¹⁹ Additionally, an undersized allograft may result in normal forces across the articular cartilage but greater forces across the meniscus.¹⁹

When sizing the recipient knee for MAT, accurate width and length measurements are critical. The most common technique used today includes measurements using anteroposterior and lateral radiographic images as described by Pollard and colleagues.¹⁵ The width of the meniscus is determined by the distance between 2 vertical lines perpendicular to the joint line, 1 of them tangential to the margin of the tibia metaphysis and the other between the medial and lateral tibial eminence in both knees (Figures 1A,1B). The length of the meniscus is measured on a lateral radiograph. A line is drawn at the level of the articular line between the anterior surface of the tibia above the tuberosity and a parallel line that is tangential to the posterior margin of the tibial plateau. Percent corrections are performed for these dimensions as described in previous publications.

Other techniques have been described to obtain accurate measurements of the recipient knee. For example, obtaining an MRI of the contralateral knee may provide a reproducible method of measuring both the width and length of the medial and lateral menisci.²⁰ CT has been used to measure the lateral meniscus independently, and it has been shown to exhibit less error in the measure of the tibial plateau when compared with X-rays.¹⁸ Both CT and MRI are more expensive than simple radiographs, and CT exposes the patient to an increased amount of radiation. Current evidence does not support standard use of these advanced imaging modalities for meniscal sizing.

Continue to: GRAFT PREPARATION AND PLACEMENT...

3. GRAFT PREPARATION AND PLACEMENT

At the time of surgery, the meniscus allograft is thawed in sterile saline and prepared on the back table. This can be done before or after the diagnostic arthroscopy and bone-slot preparation. Excess soft tissue surrounding the meniscal rim and/or anterior and posterior horns should be removed. Several techniques for MAT have been described, but we generally prefer a bridge-in-slot technique for both medial and lateral MAT.²¹ To prepare the meniscus allograft for a bridge-in-slot technique, the graft is cut with an oscillating saw to a width of 7 mm, with care taken to ensure that the bony insertions of both meniscal horns are preserved. Next, a transverse cut is made 10 mm below the meniscal horns to set the depth of the bone bridge. To assist with the sizing of the bone bridge, a rectangular sizing block and cutting jig is used (Figures 2A-2C). After marking the middle and posterior thirds of the meniscus, a No. 2 non-absorbable suture is placed at the junction of the posterior and middle thirds of the meniscus. This completes preparation of the allograft prior to implantation.

Attention is then turned to back the arthroscopy. A standard posteromedial (medial meniscus) or posterolateral (lateral meniscus) accessory incision is made, and a Henning retractor is carefully placed in order to receive the sutures that will be placed through the meniscus allograft via a standard inside-out repair technique. First, a zone-specific cannula is used to place a nitinol wire out the accessory incision. The looped end of the wire is pulled out of the anterior arthrotomy incision that will be used to shuttle the meniscus allograft into the joint. In order to pass the meniscal allograft into the joint, the passing suture previously placed through the meniscus is shuttled through the nitinol wire, and the wire is then pulled out the accessory incision, advancing the meniscus through the anteiror arthrotomy. As the meniscus is introduced, the traction suture is then gently tensioned to get the allograft completely into the joint. Next, the bone bridge is seated into the previously created bone slot, as the soft tissue component is manually pushed beneath the ipsilateral femoral condyle. Under direct visualization, the soft tissue component is reduced with a probe using firm, constant traction. To aid in reduction, it may be useful to apply compartment-specific varus or valgus stress and to cycle the knee once the meniscal complex is reduced.

4. GRAFT FIXATION

Once the graft has been passed completely into the joint, with the bone bridge seated into the bone slot, the long end of an Army-Navy retractor is placed firmly through the arthrotomy on the meniscal bone bridge, maintaining a downward force to allow the bridge to remain slotted. To lever down on the posterior aspect of the graft, a freer elevator is used from anterosuperior to posteroinferior. The bone bridge is then secured using a bioabsorbable interference screw, placed central to the bone bridge opposing the block to the ipsilateral compartment. The remainder of the meniscus is secured with an inside-out repair technique, working from posterior to anterior through a standard medial or lateral meniscal repair approach. In total, approximately 6 to 10 vertical mattress sutures are placed, and these can be placed both superiorly and inferiorly on the meniscus. Posteriorly, an all-inside suture repair device may be helpful. Finally, the anterior aspect of the meniscus is repaired to the capsule in an open fashion prior to closing the arthrotomy. Sutures are tied with the leg in extension. The meniscal repair incision is closed in a standard fashion using layers.

5. CONCOMITANT PATHOLOGY AND MAT

The presence of concomitant knee pathology in the context of meniscus deficiency is a challenging problem that requires careful attention to all aspects of the underlying condition of the knee. In cases where MAT is indicated, issues of malalignment, cartilage defects, and/or ligamentous instability may also need to be addressed either concomitantly or in staged fashion. For example, medial meniscal deficiency in the setting of varus alignment can be addressed with a concomitant HTO, whereas lateral meniscal deficiency in the setting of valgus malalignment can be addressed with a concomitant DFO. In both cases, the osteotomy corrects an abnormal mechanical axis, offloading the diseased compartment. This accomplishes 2 goals, namely to preserve the new MAT graft and to protect underlying articular cartilage.^22-24 The osteotomy is an important contributor to additional pain relief by offloading the compartment, and clinical studies have demonstrated that failure to address malalignment in the setting of surgical intervention for cartilage and meniscal insufficiency leads to inferior clinical outcomes and poor survival of transplanted tissue.^25-28

Continue to: In a meniscus-deficient patient with chondral lesions...

In a meniscus-deficient patient with chondral lesions (Outerbridge grade 3 or 4), concomitant MAT and cartilage restoration should be considered. Depending on the size and location of the chondral lesion, options include marrow stimulation, autologous chondrocyte implantation, osteochondral autograft transfer, as well as chondral and/or osteochondral allograft transplantation. In a systematic review of concomitant MAT and cartilage restoration procedures, Harris and colleagues²⁵ found that failure rates of the combined surgery were similar to those of either surgery in isolation.

Young athletes sustaining anterior cruciate ligament (ACL) tears commonly also have meniscal pathology that must be addressed. Most cases are treated with meniscal repair or partial meniscectomy, but occasionally patients present with ACL tear and symptomatic meniscal deficiency. Specifically, MAT survival relies largely on a knee with ligamentous stability, whereas outcomes of ACL reconstruction are improved with intact and functional menisci.²⁹ The surgical technique for MAT is modified slightly in the setting of performing a concomitant ACL reconstruction, with the ACL tibial tunnel drilled to avoid the meniscal bone slot if possible, followed by femoral tunnel creation. Femoral fixation of the ACL graft is accomplished after preparation of the meniscal slot. The meniscal graft is set into place (sutures are not yet tied), and tibial fixation of the ACL graft is performed next. We typically use an Achilles allograft for the ACL reconstruction, with the bone block used for femoral fixation to avoid bony impingement between the MAT bone bridge/block and the ACL graft. With the knee in full extension, the MAT sutures are tied at the conclusion of the surgical procedure. Concomitant MAT and ACL reconstruction has yielded positive long-term clinical outcomes, improved joint stability, and findings similar to historical results of ACL reconstruction or MAT performed in isolation.^30,31

CONCLUSION

When used with the proper indications, MAT has demonstrated the ability to restore function and reduce pain. Successful meniscal transplant requires attention to the patient’s past medical and surgical history. Similarly, care must be taken to address any concomitant knee pathology, such as coronal realignment, ligament reconstruction, or cartilage restoration.

ABSTRACT

An increasing interest focuses on the rates and risk factors for hospital readmission. However, little is known regarding the readmission following total shoulder arthroplasty (TSA). This study aims to determine the rates, risk factors, and reasons for hospital readmission following primary TSA. Patients undergoing TSA (anatomic or reverse) as part of the American College of Surgeons National Surgical Quality Improvement Program in 2011 to 2013 were identified. The rate of unplanned readmission to the hospital within 30 postoperative days was characterized. Using multivariate regression, demographic and comorbidity factors were tested for independent association with readmission. Finally, the reasons for readmission were characterized. A total of 3627 patients were identified. Among the admitted patients, 93 (2.56%) were readmitted within 30 days of surgery. The independent risk factors for readmission included old age (for age 60-69 years, relative risk [RR] = 1.6; for age 70-79 years, RR = 2.3; for age ≥80 years, RR = 23.1; P = .042), male sex (RR = 1.6, P = .025), anemia (RR = 1.9, P = .005), and dependent functional status (RR = 2.8, P = .012). The reasons for readmission were available for 84 of the 93 readmitted patients. The most common reasons for readmission comprised pneumonia (14 cases, 16.7%), dislocation (7 cases, 8.3%), pulmonary embolism (7 cases, 8.3%), and surgical site infection (6 cases, 7.1%). Unplanned readmission occurs following about 1 in 40 cases of TSA. The most common causes of readmission include pneumonia, dislocation, pulmonary embolism, and surgical site infection. Patients with old age, male sex, anemia, and dependent functional status are at higher risk for readmission and should be counseled and monitored accordingly.

Continue to: Total shoulder arthroplasty...

Total shoulder arthroplasty (TSA) is performed with increasing frequency in the United States and is considered to be cost-effective.^1-4 Following the procedure, patients generally achieve shoulder function and pain relief.^5-8 Despite the success of the procedure, the growing literature on TSA has also reported rates of complications between 3.6% and 25% of the treated patients.^9-16

In recent years, an increasing interest has focused on the rates and risk factors for unplanned hospital readmissions; these variables may not only reflect the quality of patient care but also result in considerable costs to the healthcare system. For instance, among Medicare patients, readmissions within 30 days of discharge occur in almost 20% of cases, costing $17.4 billion per year.¹⁷ Readmission rates increasingly factor into hospital performance metrics and reimbursement, including the Hospital Readmissions Reduction Program of the Patient Protection and Affordable Care Act that reduces Centers for Medicare and Medicaid Services payments to hospitals with high 30-day readmission rates.¹⁸

To date, only a few studies have evaluated readmission following TSA, with 30- to 90-day readmission rates ranging from 4.5% to 7.3%.^19-23 These studies comprised single institution series^20,22 and analyses of administrative databases.^19,21,23 Most studies have shown that readmission occurs more often for medical than surgical reasons, with surgical reasons most commonly including infection and dislocation.^19-23 However, only limited analyses have been conducted regarding risk factors for readmission.^21,23 To date and to our knowledge, no study has investigated reasons for readmission following TSA using nationwide data.

This study aims to determine the rates, risk factors, and reasons for hospital readmission following primary TSA in the United States using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database.

METHODS

DATA SOURCE

The NSQIP database was utilized to address the study purpose. NSQIP is a nationwide prospective surgical registry established by the American College of Surgeons and reports data from academic and community hospitals across the United States.²⁴ Patients undertaking surgery at these centers are followed by the surgical clinical reviewers at the participating NSQIP sites prospectively for 30 days following the procedure to record complications including readmission. Preoperative and surgical data, such as demographics, medical comorbid diseases, and operative time, are also included. Previous studies have analyzed the complications of various orthopedic surgeries using the NSQIP data.^14,16,25-30

DATA COLLECTION

We retrospectively identified from NSQIP the patients who underwent primary TSA (anatomic or reverse) in 2013 to 2014. The timeframe 2013 to 2014 was used because NSQIP only began recording reasons for readmission in 2013. The inclusion criteria were as follows: Current Procedural Terminology (CPT) code for TSA (23472); preoperative diagnosis according to the International Classification of Diseases, Ninth Revision (ICD-9) codes 714.0, 715.11, 715.31, 715.91, 715.21, 715.89, 716.xx 718.xx, 719.xx, 726.x, 727.xx, and 733.41 (where x is a wild card digit); and no missing demographic, comorbidity, or outcome data. Anatomic and reverse TSA were analyzed together because they share the same CPT code, and the NSQIP database prevents searching by the ICD-9 procedure code.

The rate of unplanned readmission to the hospital within 30 postoperative days was characterized. The reasons for readmission in this 30-day period were only available in 2013 and were determined using the ICD-9 diagnosis codes. Patient demographics were recorded for use in identifying potential risk factors for readmission; the demographic data included sex, age, smoking status, body mass index (BMI), and comorbidities, including end-stage renal disease, dyspnea on exertion, congestive heart failure, diabetes mellitus, hypertension, and chronic obstructive pulmonary disease (COPD).

Continue to: Statistical analysis...

STATISTICAL ANALYSIS

Statistical analyses were performed using Stata version 13.1 (StataCorp). First, using bivariate and multivariate regression, demographic and comorbidity factors were tested for independent association with readmission to the hospital within 30 days of surgery. Second, among the readmitted patients, the reasons for readmission were tabulated. Of note, the reasons for readmission were only documented for the procedures performed in 2013. All tests were 2-tailed and conducted at an α level of 0.05.

RESTULTS

A total of 3627 TSA patients were identified. The mean age (± standard deviation) was 69.4 ± 9.5 years, 55.8% of patients were female, and mean BMI was 30.1 ± 7.0 years. Table 1 provides the additional demographic data. Of the 3627 included patients, 93 (2.56%) were readmitted within 30 days of surgery. The 95% confidence interval for the estimated rate of readmission reached 2.05% to 3.08%.

Table 1. Patient Population

Abbreviation: COPD, chronic obstructive pulmonary disease.

In the bivariate analyses (Table 2), the following factors were positively associated readmission: older age (60-69 years, relative risk [RR] = 1.6; 70-79 years, RR = 2.2; ≥80 years, RR = 3.3; P = .011), dependent functional status (RR = 2.9, P = .008), and anemia (RR = 2.2, P < .001).

Table 2. Bivariate Analysis of Risk Factors for Readmission

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; RR, relative risk.

In the multivariate analyses (Table 3), the following factors were independent risk factors for readmission: older age (60-69 years, RR = 1.6; 70-79 years, RR = 2.3; ≥80 years, RR = 3.1; P =.027), male sex (RR = 1.6, P = .025), anemia (RR = 1.9, P = .005), and dependent functional status (RR = 2.8, P = .012). Interestingly, readmission showed no independent association with diabetes, dyspnea on exertion, BMI, COPD, hypertension, or current smoking status (P > .05 for each).

Table 3. Independent Risk Factors for Readmission on Multivariate Analysis

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; RR, relative risk.

Continue to: Table 4...

The reasons for readmission were available for 84 of the 93 readmitted patients. The most common reasons for readmission included pneumonia (14 cases, 16.7%), dislocation (7 cases, 8.3%), pulmonary embolism (7 cases, 8.3%), and surgical site infection (6 cases, 7.1%) (Table 4).

Table 4. Reasons for Readmission

DISCUSSION

Our analysis of 3042 TSAs from the NSQIP database suggests that unplanned readmission to the hospital occurs following about 1 in 40 cases of TSA. The study also suggests that the most common reasons for readmission encompass pneumonia, dislocation, pulmonary embolism, and surgical site infection. Old age, male sex, anemia, and dependent functional status serve as risk factors for readmission, and patients with such factors should be counseled and monitored accordingly.

In recent years, an increasing emphasis has centered on reducing rates of hospital readmission, with programs such as the Hospital Readmissions Reduction Program of the Affordable Care Act cutting reimbursements for hospitals with high 30-day readmission rates.^17,18 To date, only a few studies have evaluated the reasons for readmission and readmission rates for TSA.^19-23 Initial reports consisted of single-institution TSA registry reviews. For example, Mahoney and colleagues²⁰ retrospectively evaluated shoulder arthroplasty procedures at their institution to document the readmission rates, finding a 5.9% readmission rate at 30 days. Readmission occurred more frequently in the first 30 days following discharge than in the 30- to 90-day period, with the most common reasons for readmission including medical complications, infection, and dislocation. Streubel and colleagues²² evaluated reoperation rates from their institution’s TSA registry, finding a 0.6% reoperation rate for primary TSA at 30 days and 1.5% for revision TSA. Instability and infection were the most common indications for reoperation. Our findings confirm these single-institution results and demonstrate their application to a nationwide sample of TSA, not just to high-volume academic centers. We similarly observed that dislocation, surgical site infection, and medical complications (mostly pneumonia and pulmonary embolism) were common causes of readmission, and that the 30-day readmission rate was about 1 in 40.

Several authors have since used statewide databases to analyze and determine risk factors for readmission following TSA. Lyman and colleagues¹⁹ used the New York State Database to show that higher hospital TSA surgical volume was associated with a lower rate of readmission when age and comorbidities were controlled for in a multivariate model. Old age was also associated with an increased readmission rate in their multivariate analysis, but comorbidities (as measured by the Charlson comorbidity index) presented a nonsignificant associative trend. These authors opted not to determine specific causes of readmission. Schairer and colleagues²¹ used State Inpatient Databases from 7 states, finding a 90-day readmission rate of 7.3%, 82% of which were due to medical complications and 18% of which were due to surgical complications (mostly infection and dislocation). Their multivariate regression revealed that male sex, reverse TSA, Medicaid insurance, patients discharged to inpatient rehabilitation or nursing facilities, medical comorbidities, and low-volume TSA hospitals were associated with readmission. Zhang and colleagues²³ used the same source to show that the 90-day readmission rate reached 14% for surgically treated proximal humerus fractures and higher for patients who underwent open reduction internal fixation, were female, were African American, were discharged to a nursing facility, possessed Medicaid insurance, or experienced medical comorbidities. Most recently, Basques and colleagues³¹ analyzed 1505 TSA cases from 2011 and 2012 in the NSQIP database, finding a 3.3% rate of readmission, with heart disease and hypertension as risk factors for readmission. Although the limitations of the NSQIP database prevented us from analyzing surgeon and hospital TSA volume or reverse vs anatomic TSA, our results confirm that the findings from statewide database studies apply to the United States nationwide NSQIP database. Old patient age, male sex, and medical comorbidities (anemia and dependent functional status) are independent risk factors for TSA readmission. We identified pneumonia, dislocation, pulmonary embolism, and surgical site infection as the most common reasons for readmission.

This study features several limitations that should be considered when interpreting the results. Anatomic and reverse TSA share a CPT code and were not separated using NSQIP data. A number of studies have reported that reverse TSA may place patients at higher risk for readmission;^20,21 however, confounding by other patient factors could play a role in this finding. The 30-day timeframe for readmission is another potential limitation; however, this timeframe is frequently used in other studies and is the relevant timeframe for the reduced reimbursement penalties from the Hospital Readmissions Reduction Program of the Affordable Care Act.¹⁸ Furthermore, the NSQIP database contains no information on surgeon or hospital TSA volume, which is a result of safeguards for patient and provider privacy. Additionally, readmission data were only available for 2011 to 2013, with causes of readmission only present in 2013. Although provided with such current information, we cannot analyze readmission trends over time, such as in response to the Affordable Care Act of 2010. Finally, although NSQIP surgical clinical reviewers strive to identify readmissions to other hospitals during their reviews of outpatient medical records, proportions of these readmissions are possibly missed. Therefore, our 30-day readmission rate may slightly underestimate the true rate.

Despite these limitations, the NSQIP database offers a unique opportunity to examine risk factors and reasons for readmission following TSA. The prior literature on readmission following TSA stemmed either from limited samples or administrative data, which feature known limitations.³² By utilizing a large, prospective, non-administrative, nationwide sample, our findings are probably both more reliable and generalizable to the country as a whole.

CONCLUSION

Unplanned readmission occurs following about 1 in 40 cases of TSA. The most common causes of readmission include pneumonia, dislocation, pulmonary embolism, and surgical site infection. Patients with old age, male sex, anemia, and dependent functional status are at a higher risk for readmission and should be counseled and monitored accordingly.

This paper will be judged for the Resident Writer’s Award.

ABSTRACT

An increasing interest focuses on the rates and risk factors for hospital readmission. However, little is known regarding the readmission following total shoulder arthroplasty (TSA). This study aims to determine the rates, risk factors, and reasons for hospital readmission following primary TSA. Patients undergoing TSA (anatomic or reverse) as part of the American College of Surgeons National Surgical Quality Improvement Program in 2011 to 2013 were identified. The rate of unplanned readmission to the hospital within 30 postoperative days was characterized. Using multivariate regression, demographic and comorbidity factors were tested for independent association with readmission. Finally, the reasons for readmission were characterized. A total of 3627 patients were identified. Among the admitted patients, 93 (2.56%) were readmitted within 30 days of surgery. The independent risk factors for readmission included old age (for age 60-69 years, relative risk [RR] = 1.6; for age 70-79 years, RR = 2.3; for age ≥80 years, RR = 23.1; P = .042), male sex (RR = 1.6, P = .025), anemia (RR = 1.9, P = .005), and dependent functional status (RR = 2.8, P = .012). The reasons for readmission were available for 84 of the 93 readmitted patients. The most common reasons for readmission comprised pneumonia (14 cases, 16.7%), dislocation (7 cases, 8.3%), pulmonary embolism (7 cases, 8.3%), and surgical site infection (6 cases, 7.1%). Unplanned readmission occurs following about 1 in 40 cases of TSA. The most common causes of readmission include pneumonia, dislocation, pulmonary embolism, and surgical site infection. Patients with old age, male sex, anemia, and dependent functional status are at higher risk for readmission and should be counseled and monitored accordingly.

Continue to: Total shoulder arthroplasty...

Total shoulder arthroplasty (TSA) is performed with increasing frequency in the United States and is considered to be cost-effective.^1-4 Following the procedure, patients generally achieve shoulder function and pain relief.^5-8 Despite the success of the procedure, the growing literature on TSA has also reported rates of complications between 3.6% and 25% of the treated patients.^9-16

In recent years, an increasing interest has focused on the rates and risk factors for unplanned hospital readmissions; these variables may not only reflect the quality of patient care but also result in considerable costs to the healthcare system. For instance, among Medicare patients, readmissions within 30 days of discharge occur in almost 20% of cases, costing $17.4 billion per year.¹⁷ Readmission rates increasingly factor into hospital performance metrics and reimbursement, including the Hospital Readmissions Reduction Program of the Patient Protection and Affordable Care Act that reduces Centers for Medicare and Medicaid Services payments to hospitals with high 30-day readmission rates.¹⁸

To date, only a few studies have evaluated readmission following TSA, with 30- to 90-day readmission rates ranging from 4.5% to 7.3%.^19-23 These studies comprised single institution series^20,22 and analyses of administrative databases.^19,21,23 Most studies have shown that readmission occurs more often for medical than surgical reasons, with surgical reasons most commonly including infection and dislocation.^19-23 However, only limited analyses have been conducted regarding risk factors for readmission.^21,23 To date and to our knowledge, no study has investigated reasons for readmission following TSA using nationwide data.

This study aims to determine the rates, risk factors, and reasons for hospital readmission following primary TSA in the United States using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database.

METHODS

DATA SOURCE

The NSQIP database was utilized to address the study purpose. NSQIP is a nationwide prospective surgical registry established by the American College of Surgeons and reports data from academic and community hospitals across the United States.²⁴ Patients undertaking surgery at these centers are followed by the surgical clinical reviewers at the participating NSQIP sites prospectively for 30 days following the procedure to record complications including readmission. Preoperative and surgical data, such as demographics, medical comorbid diseases, and operative time, are also included. Previous studies have analyzed the complications of various orthopedic surgeries using the NSQIP data.^14,16,25-30

DATA COLLECTION

We retrospectively identified from NSQIP the patients who underwent primary TSA (anatomic or reverse) in 2013 to 2014. The timeframe 2013 to 2014 was used because NSQIP only began recording reasons for readmission in 2013. The inclusion criteria were as follows: Current Procedural Terminology (CPT) code for TSA (23472); preoperative diagnosis according to the International Classification of Diseases, Ninth Revision (ICD-9) codes 714.0, 715.11, 715.31, 715.91, 715.21, 715.89, 716.xx 718.xx, 719.xx, 726.x, 727.xx, and 733.41 (where x is a wild card digit); and no missing demographic, comorbidity, or outcome data. Anatomic and reverse TSA were analyzed together because they share the same CPT code, and the NSQIP database prevents searching by the ICD-9 procedure code.

The rate of unplanned readmission to the hospital within 30 postoperative days was characterized. The reasons for readmission in this 30-day period were only available in 2013 and were determined using the ICD-9 diagnosis codes. Patient demographics were recorded for use in identifying potential risk factors for readmission; the demographic data included sex, age, smoking status, body mass index (BMI), and comorbidities, including end-stage renal disease, dyspnea on exertion, congestive heart failure, diabetes mellitus, hypertension, and chronic obstructive pulmonary disease (COPD).

Continue to: Statistical analysis...

STATISTICAL ANALYSIS

Statistical analyses were performed using Stata version 13.1 (StataCorp). First, using bivariate and multivariate regression, demographic and comorbidity factors were tested for independent association with readmission to the hospital within 30 days of surgery. Second, among the readmitted patients, the reasons for readmission were tabulated. Of note, the reasons for readmission were only documented for the procedures performed in 2013. All tests were 2-tailed and conducted at an α level of 0.05.

RESTULTS

A total of 3627 TSA patients were identified. The mean age (± standard deviation) was 69.4 ± 9.5 years, 55.8% of patients were female, and mean BMI was 30.1 ± 7.0 years. Table 1 provides the additional demographic data. Of the 3627 included patients, 93 (2.56%) were readmitted within 30 days of surgery. The 95% confidence interval for the estimated rate of readmission reached 2.05% to 3.08%.

Table 1. Patient Population

Abbreviation: COPD, chronic obstructive pulmonary disease.

In the bivariate analyses (Table 2), the following factors were positively associated readmission: older age (60-69 years, relative risk [RR] = 1.6; 70-79 years, RR = 2.2; ≥80 years, RR = 3.3; P = .011), dependent functional status (RR = 2.9, P = .008), and anemia (RR = 2.2, P < .001).

Table 2. Bivariate Analysis of Risk Factors for Readmission

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; RR, relative risk.

In the multivariate analyses (Table 3), the following factors were independent risk factors for readmission: older age (60-69 years, RR = 1.6; 70-79 years, RR = 2.3; ≥80 years, RR = 3.1; P =.027), male sex (RR = 1.6, P = .025), anemia (RR = 1.9, P = .005), and dependent functional status (RR = 2.8, P = .012). Interestingly, readmission showed no independent association with diabetes, dyspnea on exertion, BMI, COPD, hypertension, or current smoking status (P > .05 for each).

Table 3. Independent Risk Factors for Readmission on Multivariate Analysis

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; RR, relative risk.

Continue to: Table 4...

The reasons for readmission were available for 84 of the 93 readmitted patients. The most common reasons for readmission included pneumonia (14 cases, 16.7%), dislocation (7 cases, 8.3%), pulmonary embolism (7 cases, 8.3%), and surgical site infection (6 cases, 7.1%) (Table 4).

Table 4. Reasons for Readmission

DISCUSSION

Our analysis of 3042 TSAs from the NSQIP database suggests that unplanned readmission to the hospital occurs following about 1 in 40 cases of TSA. The study also suggests that the most common reasons for readmission encompass pneumonia, dislocation, pulmonary embolism, and surgical site infection. Old age, male sex, anemia, and dependent functional status serve as risk factors for readmission, and patients with such factors should be counseled and monitored accordingly.

In recent years, an increasing emphasis has centered on reducing rates of hospital readmission, with programs such as the Hospital Readmissions Reduction Program of the Affordable Care Act cutting reimbursements for hospitals with high 30-day readmission rates.^17,18 To date, only a few studies have evaluated the reasons for readmission and readmission rates for TSA.^19-23 Initial reports consisted of single-institution TSA registry reviews. For example, Mahoney and colleagues²⁰ retrospectively evaluated shoulder arthroplasty procedures at their institution to document the readmission rates, finding a 5.9% readmission rate at 30 days. Readmission occurred more frequently in the first 30 days following discharge than in the 30- to 90-day period, with the most common reasons for readmission including medical complications, infection, and dislocation. Streubel and colleagues²² evaluated reoperation rates from their institution’s TSA registry, finding a 0.6% reoperation rate for primary TSA at 30 days and 1.5% for revision TSA. Instability and infection were the most common indications for reoperation. Our findings confirm these single-institution results and demonstrate their application to a nationwide sample of TSA, not just to high-volume academic centers. We similarly observed that dislocation, surgical site infection, and medical complications (mostly pneumonia and pulmonary embolism) were common causes of readmission, and that the 30-day readmission rate was about 1 in 40.

Several authors have since used statewide databases to analyze and determine risk factors for readmission following TSA. Lyman and colleagues¹⁹ used the New York State Database to show that higher hospital TSA surgical volume was associated with a lower rate of readmission when age and comorbidities were controlled for in a multivariate model. Old age was also associated with an increased readmission rate in their multivariate analysis, but comorbidities (as measured by the Charlson comorbidity index) presented a nonsignificant associative trend. These authors opted not to determine specific causes of readmission. Schairer and colleagues²¹ used State Inpatient Databases from 7 states, finding a 90-day readmission rate of 7.3%, 82% of which were due to medical complications and 18% of which were due to surgical complications (mostly infection and dislocation). Their multivariate regression revealed that male sex, reverse TSA, Medicaid insurance, patients discharged to inpatient rehabilitation or nursing facilities, medical comorbidities, and low-volume TSA hospitals were associated with readmission. Zhang and colleagues²³ used the same source to show that the 90-day readmission rate reached 14% for surgically treated proximal humerus fractures and higher for patients who underwent open reduction internal fixation, were female, were African American, were discharged to a nursing facility, possessed Medicaid insurance, or experienced medical comorbidities. Most recently, Basques and colleagues³¹ analyzed 1505 TSA cases from 2011 and 2012 in the NSQIP database, finding a 3.3% rate of readmission, with heart disease and hypertension as risk factors for readmission. Although the limitations of the NSQIP database prevented us from analyzing surgeon and hospital TSA volume or reverse vs anatomic TSA, our results confirm that the findings from statewide database studies apply to the United States nationwide NSQIP database. Old patient age, male sex, and medical comorbidities (anemia and dependent functional status) are independent risk factors for TSA readmission. We identified pneumonia, dislocation, pulmonary embolism, and surgical site infection as the most common reasons for readmission.

This study features several limitations that should be considered when interpreting the results. Anatomic and reverse TSA share a CPT code and were not separated using NSQIP data. A number of studies have reported that reverse TSA may place patients at higher risk for readmission;^20,21 however, confounding by other patient factors could play a role in this finding. The 30-day timeframe for readmission is another potential limitation; however, this timeframe is frequently used in other studies and is the relevant timeframe for the reduced reimbursement penalties from the Hospital Readmissions Reduction Program of the Affordable Care Act.¹⁸ Furthermore, the NSQIP database contains no information on surgeon or hospital TSA volume, which is a result of safeguards for patient and provider privacy. Additionally, readmission data were only available for 2011 to 2013, with causes of readmission only present in 2013. Although provided with such current information, we cannot analyze readmission trends over time, such as in response to the Affordable Care Act of 2010. Finally, although NSQIP surgical clinical reviewers strive to identify readmissions to other hospitals during their reviews of outpatient medical records, proportions of these readmissions are possibly missed. Therefore, our 30-day readmission rate may slightly underestimate the true rate.

Despite these limitations, the NSQIP database offers a unique opportunity to examine risk factors and reasons for readmission following TSA. The prior literature on readmission following TSA stemmed either from limited samples or administrative data, which feature known limitations.³² By utilizing a large, prospective, non-administrative, nationwide sample, our findings are probably both more reliable and generalizable to the country as a whole.

CONCLUSION

Unplanned readmission occurs following about 1 in 40 cases of TSA. The most common causes of readmission include pneumonia, dislocation, pulmonary embolism, and surgical site infection. Patients with old age, male sex, anemia, and dependent functional status are at a higher risk for readmission and should be counseled and monitored accordingly.

This paper will be judged for the Resident Writer’s Award.

ABSTRACT

An increasing interest focuses on the rates and risk factors for hospital readmission. However, little is known regarding the readmission following total shoulder arthroplasty (TSA). This study aims to determine the rates, risk factors, and reasons for hospital readmission following primary TSA. Patients undergoing TSA (anatomic or reverse) as part of the American College of Surgeons National Surgical Quality Improvement Program in 2011 to 2013 were identified. The rate of unplanned readmission to the hospital within 30 postoperative days was characterized. Using multivariate regression, demographic and comorbidity factors were tested for independent association with readmission. Finally, the reasons for readmission were characterized. A total of 3627 patients were identified. Among the admitted patients, 93 (2.56%) were readmitted within 30 days of surgery. The independent risk factors for readmission included old age (for age 60-69 years, relative risk [RR] = 1.6; for age 70-79 years, RR = 2.3; for age ≥80 years, RR = 23.1; P = .042), male sex (RR = 1.6, P = .025), anemia (RR = 1.9, P = .005), and dependent functional status (RR = 2.8, P = .012). The reasons for readmission were available for 84 of the 93 readmitted patients. The most common reasons for readmission comprised pneumonia (14 cases, 16.7%), dislocation (7 cases, 8.3%), pulmonary embolism (7 cases, 8.3%), and surgical site infection (6 cases, 7.1%). Unplanned readmission occurs following about 1 in 40 cases of TSA. The most common causes of readmission include pneumonia, dislocation, pulmonary embolism, and surgical site infection. Patients with old age, male sex, anemia, and dependent functional status are at higher risk for readmission and should be counseled and monitored accordingly.

Continue to: Total shoulder arthroplasty...

Total shoulder arthroplasty (TSA) is performed with increasing frequency in the United States and is considered to be cost-effective.^1-4 Following the procedure, patients generally achieve shoulder function and pain relief.^5-8 Despite the success of the procedure, the growing literature on TSA has also reported rates of complications between 3.6% and 25% of the treated patients.^9-16

In recent years, an increasing interest has focused on the rates and risk factors for unplanned hospital readmissions; these variables may not only reflect the quality of patient care but also result in considerable costs to the healthcare system. For instance, among Medicare patients, readmissions within 30 days of discharge occur in almost 20% of cases, costing $17.4 billion per year.¹⁷ Readmission rates increasingly factor into hospital performance metrics and reimbursement, including the Hospital Readmissions Reduction Program of the Patient Protection and Affordable Care Act that reduces Centers for Medicare and Medicaid Services payments to hospitals with high 30-day readmission rates.¹⁸

To date, only a few studies have evaluated readmission following TSA, with 30- to 90-day readmission rates ranging from 4.5% to 7.3%.^19-23 These studies comprised single institution series^20,22 and analyses of administrative databases.^19,21,23 Most studies have shown that readmission occurs more often for medical than surgical reasons, with surgical reasons most commonly including infection and dislocation.^19-23 However, only limited analyses have been conducted regarding risk factors for readmission.^21,23 To date and to our knowledge, no study has investigated reasons for readmission following TSA using nationwide data.

This study aims to determine the rates, risk factors, and reasons for hospital readmission following primary TSA in the United States using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database.

METHODS

DATA SOURCE

The NSQIP database was utilized to address the study purpose. NSQIP is a nationwide prospective surgical registry established by the American College of Surgeons and reports data from academic and community hospitals across the United States.²⁴ Patients undertaking surgery at these centers are followed by the surgical clinical reviewers at the participating NSQIP sites prospectively for 30 days following the procedure to record complications including readmission. Preoperative and surgical data, such as demographics, medical comorbid diseases, and operative time, are also included. Previous studies have analyzed the complications of various orthopedic surgeries using the NSQIP data.^14,16,25-30

DATA COLLECTION

We retrospectively identified from NSQIP the patients who underwent primary TSA (anatomic or reverse) in 2013 to 2014. The timeframe 2013 to 2014 was used because NSQIP only began recording reasons for readmission in 2013. The inclusion criteria were as follows: Current Procedural Terminology (CPT) code for TSA (23472); preoperative diagnosis according to the International Classification of Diseases, Ninth Revision (ICD-9) codes 714.0, 715.11, 715.31, 715.91, 715.21, 715.89, 716.xx 718.xx, 719.xx, 726.x, 727.xx, and 733.41 (where x is a wild card digit); and no missing demographic, comorbidity, or outcome data. Anatomic and reverse TSA were analyzed together because they share the same CPT code, and the NSQIP database prevents searching by the ICD-9 procedure code.

The rate of unplanned readmission to the hospital within 30 postoperative days was characterized. The reasons for readmission in this 30-day period were only available in 2013 and were determined using the ICD-9 diagnosis codes. Patient demographics were recorded for use in identifying potential risk factors for readmission; the demographic data included sex, age, smoking status, body mass index (BMI), and comorbidities, including end-stage renal disease, dyspnea on exertion, congestive heart failure, diabetes mellitus, hypertension, and chronic obstructive pulmonary disease (COPD).

Continue to: Statistical analysis...

STATISTICAL ANALYSIS

Statistical analyses were performed using Stata version 13.1 (StataCorp). First, using bivariate and multivariate regression, demographic and comorbidity factors were tested for independent association with readmission to the hospital within 30 days of surgery. Second, among the readmitted patients, the reasons for readmission were tabulated. Of note, the reasons for readmission were only documented for the procedures performed in 2013. All tests were 2-tailed and conducted at an α level of 0.05.

RESTULTS

A total of 3627 TSA patients were identified. The mean age (± standard deviation) was 69.4 ± 9.5 years, 55.8% of patients were female, and mean BMI was 30.1 ± 7.0 years. Table 1 provides the additional demographic data. Of the 3627 included patients, 93 (2.56%) were readmitted within 30 days of surgery. The 95% confidence interval for the estimated rate of readmission reached 2.05% to 3.08%.

Table 1. Patient Population

Abbreviation: COPD, chronic obstructive pulmonary disease.

In the bivariate analyses (Table 2), the following factors were positively associated readmission: older age (60-69 years, relative risk [RR] = 1.6; 70-79 years, RR = 2.2; ≥80 years, RR = 3.3; P = .011), dependent functional status (RR = 2.9, P = .008), and anemia (RR = 2.2, P < .001).

Table 2. Bivariate Analysis of Risk Factors for Readmission

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; RR, relative risk.

In the multivariate analyses (Table 3), the following factors were independent risk factors for readmission: older age (60-69 years, RR = 1.6; 70-79 years, RR = 2.3; ≥80 years, RR = 3.1; P =.027), male sex (RR = 1.6, P = .025), anemia (RR = 1.9, P = .005), and dependent functional status (RR = 2.8, P = .012). Interestingly, readmission showed no independent association with diabetes, dyspnea on exertion, BMI, COPD, hypertension, or current smoking status (P > .05 for each).

Table 3. Independent Risk Factors for Readmission on Multivariate Analysis

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; RR, relative risk.

Continue to: Table 4...

The reasons for readmission were available for 84 of the 93 readmitted patients. The most common reasons for readmission included pneumonia (14 cases, 16.7%), dislocation (7 cases, 8.3%), pulmonary embolism (7 cases, 8.3%), and surgical site infection (6 cases, 7.1%) (Table 4).

Table 4. Reasons for Readmission

DISCUSSION

Our analysis of 3042 TSAs from the NSQIP database suggests that unplanned readmission to the hospital occurs following about 1 in 40 cases of TSA. The study also suggests that the most common reasons for readmission encompass pneumonia, dislocation, pulmonary embolism, and surgical site infection. Old age, male sex, anemia, and dependent functional status serve as risk factors for readmission, and patients with such factors should be counseled and monitored accordingly.

In recent years, an increasing emphasis has centered on reducing rates of hospital readmission, with programs such as the Hospital Readmissions Reduction Program of the Affordable Care Act cutting reimbursements for hospitals with high 30-day readmission rates.^17,18 To date, only a few studies have evaluated the reasons for readmission and readmission rates for TSA.^19-23 Initial reports consisted of single-institution TSA registry reviews. For example, Mahoney and colleagues²⁰ retrospectively evaluated shoulder arthroplasty procedures at their institution to document the readmission rates, finding a 5.9% readmission rate at 30 days. Readmission occurred more frequently in the first 30 days following discharge than in the 30- to 90-day period, with the most common reasons for readmission including medical complications, infection, and dislocation. Streubel and colleagues²² evaluated reoperation rates from their institution’s TSA registry, finding a 0.6% reoperation rate for primary TSA at 30 days and 1.5% for revision TSA. Instability and infection were the most common indications for reoperation. Our findings confirm these single-institution results and demonstrate their application to a nationwide sample of TSA, not just to high-volume academic centers. We similarly observed that dislocation, surgical site infection, and medical complications (mostly pneumonia and pulmonary embolism) were common causes of readmission, and that the 30-day readmission rate was about 1 in 40.

Several authors have since used statewide databases to analyze and determine risk factors for readmission following TSA. Lyman and colleagues¹⁹ used the New York State Database to show that higher hospital TSA surgical volume was associated with a lower rate of readmission when age and comorbidities were controlled for in a multivariate model. Old age was also associated with an increased readmission rate in their multivariate analysis, but comorbidities (as measured by the Charlson comorbidity index) presented a nonsignificant associative trend. These authors opted not to determine specific causes of readmission. Schairer and colleagues²¹ used State Inpatient Databases from 7 states, finding a 90-day readmission rate of 7.3%, 82% of which were due to medical complications and 18% of which were due to surgical complications (mostly infection and dislocation). Their multivariate regression revealed that male sex, reverse TSA, Medicaid insurance, patients discharged to inpatient rehabilitation or nursing facilities, medical comorbidities, and low-volume TSA hospitals were associated with readmission. Zhang and colleagues²³ used the same source to show that the 90-day readmission rate reached 14% for surgically treated proximal humerus fractures and higher for patients who underwent open reduction internal fixation, were female, were African American, were discharged to a nursing facility, possessed Medicaid insurance, or experienced medical comorbidities. Most recently, Basques and colleagues³¹ analyzed 1505 TSA cases from 2011 and 2012 in the NSQIP database, finding a 3.3% rate of readmission, with heart disease and hypertension as risk factors for readmission. Although the limitations of the NSQIP database prevented us from analyzing surgeon and hospital TSA volume or reverse vs anatomic TSA, our results confirm that the findings from statewide database studies apply to the United States nationwide NSQIP database. Old patient age, male sex, and medical comorbidities (anemia and dependent functional status) are independent risk factors for TSA readmission. We identified pneumonia, dislocation, pulmonary embolism, and surgical site infection as the most common reasons for readmission.

This study features several limitations that should be considered when interpreting the results. Anatomic and reverse TSA share a CPT code and were not separated using NSQIP data. A number of studies have reported that reverse TSA may place patients at higher risk for readmission;^20,21 however, confounding by other patient factors could play a role in this finding. The 30-day timeframe for readmission is another potential limitation; however, this timeframe is frequently used in other studies and is the relevant timeframe for the reduced reimbursement penalties from the Hospital Readmissions Reduction Program of the Affordable Care Act.¹⁸ Furthermore, the NSQIP database contains no information on surgeon or hospital TSA volume, which is a result of safeguards for patient and provider privacy. Additionally, readmission data were only available for 2011 to 2013, with causes of readmission only present in 2013. Although provided with such current information, we cannot analyze readmission trends over time, such as in response to the Affordable Care Act of 2010. Finally, although NSQIP surgical clinical reviewers strive to identify readmissions to other hospitals during their reviews of outpatient medical records, proportions of these readmissions are possibly missed. Therefore, our 30-day readmission rate may slightly underestimate the true rate.

Despite these limitations, the NSQIP database offers a unique opportunity to examine risk factors and reasons for readmission following TSA. The prior literature on readmission following TSA stemmed either from limited samples or administrative data, which feature known limitations.³² By utilizing a large, prospective, non-administrative, nationwide sample, our findings are probably both more reliable and generalizable to the country as a whole.

CONCLUSION

Unplanned readmission occurs following about 1 in 40 cases of TSA. The most common causes of readmission include pneumonia, dislocation, pulmonary embolism, and surgical site infection. Patients with old age, male sex, anemia, and dependent functional status are at a higher risk for readmission and should be counseled and monitored accordingly.

This paper will be judged for the Resident Writer’s Award.

ABSTRACT

The purpose of this study is to describe the rate of return to the operating room (OR) following microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and osteochondral allograft (OCA) procedures at 90 days, 1 year, and 2 years. Current Procedural Terminology codes for all patients undergoing MFX, ACI, OATS, and OCA were used to search a prospectively collected, commercially available private payer insurance company database from 2007 to 2011. Within 90 days, 1 year, and 2 years after surgery, the database was searched for the occurrence of these same patients undergoing knee diagnostic arthroscopy with biopsy, lysis of adhesions, synovectomy, arthroscopy for infection or lavage, arthroscopy for removal of loose bodies, chondroplasty, MFX, ACI, OATS, OCA, and/or knee arthroplasty. Descriptive statistical analysis and contingency table analysis were performed. A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX, 640 ACI, 386 open OATS, 997 arthroscopic OATS, 714 open OCA, and 894 arthroscopic OCA procedures. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. At 2 years, patients who underwent MFX, ACI, OATS, OCA had reoperation rates of 14.65%, 29.69%, 8.82%, and 12.22%, respectively. There was a statistically significantly increased risk for ACI return to OR within all intervals (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative treatment options. With a large US commercial insurance database from 2007 to 2011, reparative procedures were favored for chondral injuries, but yielded an increased risk for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative approaches, yet cell-based approaches yielded a significantly increased risk for a return to the OR.

Continue to: Symptomatic, full-thickness articular cartilage

Symptomatic, full-thickness articular cartilage defects in the knee are difficult to manage, particularly in the young, athletic patient population. Fortunately, a variety of cartilage repair (direct repair of the cartilage or those procedures which attempt to generate fibrocartilage) and restoration (those aimed at restoring hyaline cartilage) procedures are available, with encouraging short- and long-term clinical outcomes. After failure of nonoperative management, several surgical options are available for treating symptomatic focal chondral defects, including microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and open and arthroscopic osteochondral allograft (OCA) transplantation procedures.^1,2 When appropriately indicated, each of these techniques has demonstrated good to excellent clinical outcomes with respect to reducing pain and improving function.^3-5

While major complications following cartilage surgery are uncommon, the need for reoperation following an index articular cartilage operation is poorly understood. Recently, McCormick and colleagues6 found that reoperation within the first 2 years following meniscus allograft transplantation (MAT) is associated with an increased likelihood of revision MAT or future arthroplasty. Given the association between early reoperation following meniscus restoration surgery and subsequent failure, an improved understanding of the epidemiology and implications of reoperations following cartilage restoration surgery is warranted. Further, in deciding which treatment option is best suited to a particular patient, the rate of return to the operating room (OR) should be taken into consideration, as this could potentially influence surgical decision-making as to which procedure to perform, especially in value-based care decision-making environments.

The purpose of this study is to describe the rate of return to the OR for knee procedures following cartilage restoration at intervals of 90 days, 1 year, and 2 years across a large-scale US patient database. The authors hypothesize that the rate of return to the OR following knee cartilage repair or restoration procedures will be under 20% during the first post-operative year, with increasing reoperation rates over time. A secondary hypothesis is that there will be no difference in reoperation rates according to sex, but that younger patients (those younger than 40 years) will have higher reoperation rates than older patients.

METHODS

We performed a retrospective analysis of a prospectively collected, large-scale, and commercially available private payer insurance company database (PearlDiver) from 2007 to 2011. The PearlDiver database is a Health Insurance Portability and Accountability Act (HIPAA) compliant, publicly available national database consisting of a collection of private payer records, with United Health Group representing the contributing health plan. The database has more than 30 million patient records and contains Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9) codes related to orthopedic procedures. From 2007 to 2011, the private payer database captured between 5.9 million and 6.2 million patients per year.

Our search was based on the CPT codes for MFX (29879), ACI (27412), OATS (29866, 29867), and OCA (27415, 27416). Return to the OR for revision surgery for the above-mentioned procedures was classified as patients with a diagnosis of diagnostic arthroscopy with biopsy (CPT 29870), lysis of adhesions (CPT 29884), synovectomy (29875, 29876), arthroscopy for infection or lavage (CPT 29871), arthroscopy for removal of loose bodies (29874), chondroplasty (29877), unicompartmental knee arthroplasty (27446), total knee arthroplasty (27447), and/or patellar arthroplasty (27438). Patient records were followed for reoperations occurring within 90 days, 1 year, and 2 years after the index cartilage procedure. All data were compared based on patient age and sex.

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation.

Continue to: Statistical analysis...

STATISTICAL ANALYSIS

Statistical analysis of this study was primarily descriptive to demonstrate the incidence for each code at each time interval. One-way analysis of variance, Chi-square analysis, and contingency tables were used to compare the incidence of each type of procedure throughout the various time intervals. A P-value of < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS v.20 (International Business Machines).

RESULTS

A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX (92.3%) 640 ACI (1.4%), 386 open OATS (0.82%), 997 arthroscopic OATS (2.11%), 714 open OCA (1.51%), and 894 arthroscopic OCA (1.89%) procedures. A summary of the procedures performed, broken down by age and sex, is provided in Tables 1 and 2. A total of 25,149 male patients (53.3%) underwent surgical procedures compared to 22,058 female patients (46.7%). For each category of procedure (MFX, ACI, OATS, OCA), there was a significantly higher proportion of males than females undergoing surgery (P < .0001 for all). Surgical treatment with MFX was consistently the most frequently performed surgery across all age groups (92.31%), while cell-based therapy with ACI was the least frequently performed procedure across all age ranges (1.36%). Restorative OATS and OCA techniques were performed with the greatest frequency in the 15-year-old to 19-year-old age group, but were not utilized in patients over 64 years of age (Table 2).

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation.

A summary of all reoperation data is provided in Tables 3 to 7 and Figures 1 and 2. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. Patients who underwent MFX had reoperation rates of 6.05% at 90 days, 11.80% at 1 year, and 14.65% at 2 years. Patients who underwent ACI had reoperation rates of 4.53% at 90 days, 23.28% at 1 year, and 29.69% at 2 years. Patients who had open and arthroscopic OATS had reoperation rates of 3.122% and 5.12% at 90 days, 6.74% and 8.53% at 1 year, and 7.51% and 10.13% at 2 years, respectively. Patients who underwent open and arthroscopic OCA had reoperation rates of 2.52% and 3.91% at 90 days, 7.14% and 6.60% at 1 year, and 13.59% and 10.85% at 2 years (Table 3). There was a statistically significantly increased risk for reoperation following ACI within all intervals compared to all other surgical techniques (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty at 6.70%. There was no significant difference between failure rates (revision OATS/OCA or conversion to arthroplasty) between the restorative treatment options, with 14 failures for OATS (9.52% of reoperations at 2 years) compared to 22 failures for OCA (12.7% of reoperations at 2 years, P = .358). Among the entire cohort of cartilage surgery patients, arthroscopic chondroplasty was the most frequent procedure performed at the time of reoperation at all time points assessed, notably accounting for 33.08% of reoperations 2 years following microfracture, 51.58% of reoperations at 2 years following ACI, 53.06% of reoperations at 2 years following OATS, and 54.07% of reoperations at 2 years following OCA (Figure 3, Tables 4–7).

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation; OR, operating room.

Abbreviations: CPT, Current Procedural Terminology; MFX, microfracture; OR, operating room.

^aA -1 denotes No. <11 within the PearlDiver database, and exact numbers are not reported due to patient privacy considerations.

Abbreviations: ACI, autologous chondrocyte implantation; CPT, Current Procedural Terminology; OR, operating room.

Abbreviations: CPT, Current Procedural Terminology; OATS, osteochondral autograft transplantation; OR, operating room.

Abbreviations: CPT, Current Procedural Terminology; OCA, osteochondral allograft; OR, operating room.

Continue to: Discussion...

DISCUSSION

The principle findings of this study demonstrate that there is an overall reoperation rate of 14.90% at 2 years following cartilage repair/restoration surgery, with the highest reoperation rates following MFX at 90 days, and ACI at both 1 year and 2 years following the index procedure. Also, patients undergoing index MFX as the index procedure have the highest risk for conversion to arthroplasty, reoperation rates for all cartilage surgeries increase over time, and arthroscopic chondroplasty is the most frequent procedure performed at the time of reoperation.

The management of symptomatic articular cartilage knee pathology is extremely challenging. With improvements in surgical technique, instrumentation, and clinical decision-making, indications are constantly evolving. Techniques that may work for “small” defects, though there is some debate as to what constitutes a “small” defect, are not necessarily going to be successful for larger defects, and this certainly varies depending on where the defect is located within the knee joint (distal femur vs patella vs trochlea, etc.). Recently, in a 2015 analysis of 3 level I or II studies, Miller and colleagues⁷ demonstrated both MFX and OATS to be viable, cost-effective, first-line treatment options for articular cartilage injuries, with similar clinical outcomes at 8.7 years. The authors noted cumulative reoperation rates of 29% among patients undergoing MFX compared to 13% among patients undergoing OATS. While ACI and OCA procedures were not included in their study, the reported reoperation rates of 29% following MFX and 13% following OATS at nearly 10 years suggest a possible increased need for reoperation following MFX over time (approximately 15% at 2 years in our study) and a stable rate of reoperation following OATS (approximately 11% at 2 years in our study). This finding is significant, as one of the goals with these procedures is to deliver effective, long-lasting pain relief and restoration of function. Interestingly, in this study, restorative OATS and OCA techniques were performed with the greatest frequency in the 15-year-old to 19-year-old age group, but were not performed in patients older than 64 years. This may be explained by the higher prevalence of acute traumatic injuries and osteochondritis dissecans diagnoses in younger patients compared with older patients, as these diagnoses are more often indicated to undergo restorative procedures as opposed to marrow stimulation.

In a 2016 systematic review of 20 studies incorporating 1117 patients, Campbell and colleagues⁸ assessed return-to-play rates following MFX, ACI, OATS, and OCA. The authors noted that return to sport (RTS) rates were greatest following OATS (89%), followed by OCA (88%), ACI (84%), and MFX (75%). Positive prognostic factors for RTS included younger age, shorter duration of preoperative symptoms, no history of prior ipsilateral knee surgery, and smaller chondral defects. Reoperation rates between the 4 techniques were not statistically compared in their study. Interestingly, in 2013, Chalmers and colleagues⁹ conducted a separate systematic review of 20 studies comprising 1375 patients undergoing MFX, ACI, or OATS. In their study, the authors found significant advantages following ACI and OATS compared to MFX with respect to patient-reported outcome scores but noted significantly faster RTS rates with MFX. Reoperation rates were noted to be similar between the 3 procedures (25% for ACI, 21% for MFX, and 28% for OATS) at an average 3.7 years following the index procedure. When considering these 2 systematic reviews together, despite a faster RTS rate following MFX, a greater proportion of patients seem to be able to RTS over time following other procedures such as OATS, OCA, and ACI. Unfortunately, these reviews do not provide insight as to the role, if any, of reoperation on return to play rates nor on overall clinical outcome scores on patients undergoing articular cartilage surgery. However, this information is valuable when counseling athletes who are in season and would like to RTS as soon as possible as opposed to those who do not have tight time constraints for when they need to RTS.

Regardless of the cartilage technique chosen, the goals of surgery remain similar—to reduce pain and improve function. For athletes, the ultimate goal is to return to the same level of play that the athlete was able to achieve prior to injury. Certainly, the need for reoperation following a cartilage surgery has implications on pain, function, and ability to RTS. Our review of nearly 50,000 cartilage surgeries demonstrates that reoperations following cartilage repair surgery are not uncommon, with a rate of 14.90% at 2 years, and that while reoperation rates are the highest following ACI, the rate of conversion to knee arthroplasty is highest following MFX. Due to the limitations of the PearlDiver database, it is not possible to determine the clinical outcomes of patients undergoing reoperation following cartilage surgery, but certainly, given these data, reoperation is clearly not necessarily indicative of clinical failure. This is highlighted by the fact that the most common procedure performed at the time of reoperation is arthroscopic chondroplasty, which, despite being an additional surgical procedure, may be acceptable for patients who wish to RTS, particularly in the setting of an index ACI in which there may be graft hypertrophy. Ideally, additional studies incorporating a cost-effectiveness analysis of each of the procedures, incorporating reoperation rates as well as patient-reported clinical outcomes, would be helpful to truly determine the patient and societal implications of reoperation following cartilage repair/restoration.

Many of the advantages and disadvantages of the described cartilage repair/restoration procedures have been well described.^10-17 Microfracture is the most commonly utilized first-line repair/restoration option for small articular cartilage lesions, mainly due to its low cost, low morbidity, and relatively low level of difficulty.18 Despite these advantages, MFX is not without limitations, and the need for revision cartilage restoration and/or conversion to arthroplasty is concerning. In 2013, Salzmann and colleagues19 evaluated a cohort of 454 patients undergoing MFX for a symptomatic knee defect and noted a reoperation rate of 26.9% (n = 123) within 2 years of the index surgery, with risk factors for reoperation noted to include an increased number of pre-MFX ipsilateral knee surgeries, patellofemoral lesions, smoking, and lower preoperative numeric analog scale scores. The definition of reoperation in their study is unfortunately not described, and thus the extent of reoperation (arthroscopy to arthroplasty) is unclear. In a 2009 systematic review of 3122 patients (28 studies) undergoing MFX conducted by Mithoefer and colleagues,²⁰ revision rates were noted to range from 2% to 31% depending on the study analyzed, with increasing revision rates after 2 years. Unfortunately, the heterogeneity of the included studies makes it difficult to determine which patients tend to fail over time.

Continue to: OATS...

OATS is a promising cartilage restoration technique indicated for treatment of patients with large, uncontained chondral lesions, and/or lesions with both bone and cartilage loss.¹ OCA is similar to OATS but uses allograft tissue instead of autograft tissue and is typically considered a viable treatment option in larger lesions (>2 cm²).²¹ Cell-based ACI therapy has evolved substantially over the past decade and is now available as a third-generation model utilizing biodegradable 3-dimensional scaffolds seeded with chondrocytes. Reoperation rates following ACI can often be higher than those following other cartilage treatments, particularly given the known complication of graft hypertrophy and/or delamination. Harris and colleagues²² conducted a systematic review of 5276 subjects undergoing ACI (all generations), noting an overall reoperation rate of 33%, but a failure rate of 5.8% at an average of 22 months following ACI. Risk factors for reoperation included periosteal-based ACI as well as open (vs arthroscopic) ACI. In this study, we found a modestly lower return to OR rate of 29.69% at 2 years.

When the outcomes of patients undergoing OATS or OCA are compared to those of patients undergoing MFX or ACI, it can be difficult to interpret the results, as the indications for performing these procedures tend to be very different. Further, the reasons for reoperation, as well as the procedures performed at the time of reoperation, are often poorly described, making it difficult to truly quantify the risk of reoperation and the implications of reoperation for patients undergoing any of these index cartilage procedures.

Overall, in this database, the return to the OR rate approaches 15% at 2 years following cartilage surgery, with cell-based therapy demonstrating higher reoperation rates at 2 years, without the risk of conversion to arthroplasty. Reoperation rates appear to stabilize at 1 year following surgery and consist mostly of minor arthroscopic procedures. These findings can help surgeons counsel patients as to the rate and type of reoperations that can be expected following cartilage surgery. Additional research incorporating patient-reported outcomes and patient-specific risk factors are needed to complement these data as to the impact of reoperations on overall clinical outcomes. Further, studies incorporating 90-day, 1-year, and 2-year costs associated with cartilage surgery will help to determine which index procedure is the most cost effective over the short- and long-term.

LIMITATIONS

This study is not without limitations. The PearlDiver database is reliant upon accurate CPT and ICD-9 coding, which creates a potential for a reporting bias. The overall reliability of the analyses is dependent on the quality of the available data, which, as noted in previous PearlDiver studies,^18,23-28 may include inaccurate billing codes, miscoding, and/or non-coding by physicians as potential sources of error. At the time of this study, the PearlDiver database did not provide consistent data points on laterality, and thus it is possible that the reported rates of reoperation overestimate the true reoperation rate following a given procedure. Fortunately, the reoperation rates for each procedure analyzed in this database study are consistent with those previously presented in the literature. In addition, it is not uncommon for patients receiving one of these procedures to have previously been treated with one of the others. Due to the inherent limitations of the PearlDiver database, this study did not investigate concomitant procedures performed along with the index procedure, nor did it investigate confounding factors such as comorbidities. The PearlDiver database does not provide data on defect size, location within the knee, concomitant pathologies (eg, meniscus tear), prior surgeries, or patient comorbidities, and while important, these factors cannot be accounted for in our analysis. The inability to account for these important factors, particularly concomitant diagnoses, procedures, and lesion size/location, represents an important limitation of this study, as this is a source of selection bias and may influence the need for reoperation in a given patient. Despite these limitations, the results of this study are supported by previous and current literature. In addition, the PearlDiver database, as a HIPAA-compliant database, does not report exact numbers when the value of the outcome of interest is between 0 and 10, which prohibits analysis of any cartilage procedure performed in a cohort of patients greater than 1 and less than 11. Finally, while not necessarily a limitation, it should be noted that CPT 29879 is not specific for microfracture, as the code also includes abrasion arthroplasty and drilling. Due to the limitations of the methodology of searching the database for this code, it is unclear as to how many patients underwent actual microfracture vs abrasion arthroplasty.

CONCLUSION

Within a large US commercial insurance database from 2007 to 2011, reparative procedures were favored for chondral injuries, but yielded an increased risk for conversion to arthroplasty. There was no difference between failure/revision rates among the restorative approaches, yet cell-based approaches yielded a significantly increased risk for a return to the OR.

ABSTRACT

The purpose of this study is to describe the rate of return to the operating room (OR) following microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and osteochondral allograft (OCA) procedures at 90 days, 1 year, and 2 years. Current Procedural Terminology codes for all patients undergoing MFX, ACI, OATS, and OCA were used to search a prospectively collected, commercially available private payer insurance company database from 2007 to 2011. Within 90 days, 1 year, and 2 years after surgery, the database was searched for the occurrence of these same patients undergoing knee diagnostic arthroscopy with biopsy, lysis of adhesions, synovectomy, arthroscopy for infection or lavage, arthroscopy for removal of loose bodies, chondroplasty, MFX, ACI, OATS, OCA, and/or knee arthroplasty. Descriptive statistical analysis and contingency table analysis were performed. A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX, 640 ACI, 386 open OATS, 997 arthroscopic OATS, 714 open OCA, and 894 arthroscopic OCA procedures. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. At 2 years, patients who underwent MFX, ACI, OATS, OCA had reoperation rates of 14.65%, 29.69%, 8.82%, and 12.22%, respectively. There was a statistically significantly increased risk for ACI return to OR within all intervals (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative treatment options. With a large US commercial insurance database from 2007 to 2011, reparative procedures were favored for chondral injuries, but yielded an increased risk for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative approaches, yet cell-based approaches yielded a significantly increased risk for a return to the OR.

Continue to: Symptomatic, full-thickness articular cartilage

Symptomatic, full-thickness articular cartilage defects in the knee are difficult to manage, particularly in the young, athletic patient population. Fortunately, a variety of cartilage repair (direct repair of the cartilage or those procedures which attempt to generate fibrocartilage) and restoration (those aimed at restoring hyaline cartilage) procedures are available, with encouraging short- and long-term clinical outcomes. After failure of nonoperative management, several surgical options are available for treating symptomatic focal chondral defects, including microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and open and arthroscopic osteochondral allograft (OCA) transplantation procedures.^1,2 When appropriately indicated, each of these techniques has demonstrated good to excellent clinical outcomes with respect to reducing pain and improving function.^3-5

While major complications following cartilage surgery are uncommon, the need for reoperation following an index articular cartilage operation is poorly understood. Recently, McCormick and colleagues6 found that reoperation within the first 2 years following meniscus allograft transplantation (MAT) is associated with an increased likelihood of revision MAT or future arthroplasty. Given the association between early reoperation following meniscus restoration surgery and subsequent failure, an improved understanding of the epidemiology and implications of reoperations following cartilage restoration surgery is warranted. Further, in deciding which treatment option is best suited to a particular patient, the rate of return to the operating room (OR) should be taken into consideration, as this could potentially influence surgical decision-making as to which procedure to perform, especially in value-based care decision-making environments.

The purpose of this study is to describe the rate of return to the OR for knee procedures following cartilage restoration at intervals of 90 days, 1 year, and 2 years across a large-scale US patient database. The authors hypothesize that the rate of return to the OR following knee cartilage repair or restoration procedures will be under 20% during the first post-operative year, with increasing reoperation rates over time. A secondary hypothesis is that there will be no difference in reoperation rates according to sex, but that younger patients (those younger than 40 years) will have higher reoperation rates than older patients.

METHODS

We performed a retrospective analysis of a prospectively collected, large-scale, and commercially available private payer insurance company database (PearlDiver) from 2007 to 2011. The PearlDiver database is a Health Insurance Portability and Accountability Act (HIPAA) compliant, publicly available national database consisting of a collection of private payer records, with United Health Group representing the contributing health plan. The database has more than 30 million patient records and contains Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9) codes related to orthopedic procedures. From 2007 to 2011, the private payer database captured between 5.9 million and 6.2 million patients per year.

Our search was based on the CPT codes for MFX (29879), ACI (27412), OATS (29866, 29867), and OCA (27415, 27416). Return to the OR for revision surgery for the above-mentioned procedures was classified as patients with a diagnosis of diagnostic arthroscopy with biopsy (CPT 29870), lysis of adhesions (CPT 29884), synovectomy (29875, 29876), arthroscopy for infection or lavage (CPT 29871), arthroscopy for removal of loose bodies (29874), chondroplasty (29877), unicompartmental knee arthroplasty (27446), total knee arthroplasty (27447), and/or patellar arthroplasty (27438). Patient records were followed for reoperations occurring within 90 days, 1 year, and 2 years after the index cartilage procedure. All data were compared based on patient age and sex.

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation.

Continue to: Statistical analysis...

STATISTICAL ANALYSIS

Statistical analysis of this study was primarily descriptive to demonstrate the incidence for each code at each time interval. One-way analysis of variance, Chi-square analysis, and contingency tables were used to compare the incidence of each type of procedure throughout the various time intervals. A P-value of < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS v.20 (International Business Machines).

RESULTS

A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX (92.3%) 640 ACI (1.4%), 386 open OATS (0.82%), 997 arthroscopic OATS (2.11%), 714 open OCA (1.51%), and 894 arthroscopic OCA (1.89%) procedures. A summary of the procedures performed, broken down by age and sex, is provided in Tables 1 and 2. A total of 25,149 male patients (53.3%) underwent surgical procedures compared to 22,058 female patients (46.7%). For each category of procedure (MFX, ACI, OATS, OCA), there was a significantly higher proportion of males than females undergoing surgery (P < .0001 for all). Surgical treatment with MFX was consistently the most frequently performed surgery across all age groups (92.31%), while cell-based therapy with ACI was the least frequently performed procedure across all age ranges (1.36%). Restorative OATS and OCA techniques were performed with the greatest frequency in the 15-year-old to 19-year-old age group, but were not utilized in patients over 64 years of age (Table 2).

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation.

A summary of all reoperation data is provided in Tables 3 to 7 and Figures 1 and 2. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. Patients who underwent MFX had reoperation rates of 6.05% at 90 days, 11.80% at 1 year, and 14.65% at 2 years. Patients who underwent ACI had reoperation rates of 4.53% at 90 days, 23.28% at 1 year, and 29.69% at 2 years. Patients who had open and arthroscopic OATS had reoperation rates of 3.122% and 5.12% at 90 days, 6.74% and 8.53% at 1 year, and 7.51% and 10.13% at 2 years, respectively. Patients who underwent open and arthroscopic OCA had reoperation rates of 2.52% and 3.91% at 90 days, 7.14% and 6.60% at 1 year, and 13.59% and 10.85% at 2 years (Table 3). There was a statistically significantly increased risk for reoperation following ACI within all intervals compared to all other surgical techniques (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty at 6.70%. There was no significant difference between failure rates (revision OATS/OCA or conversion to arthroplasty) between the restorative treatment options, with 14 failures for OATS (9.52% of reoperations at 2 years) compared to 22 failures for OCA (12.7% of reoperations at 2 years, P = .358). Among the entire cohort of cartilage surgery patients, arthroscopic chondroplasty was the most frequent procedure performed at the time of reoperation at all time points assessed, notably accounting for 33.08% of reoperations 2 years following microfracture, 51.58% of reoperations at 2 years following ACI, 53.06% of reoperations at 2 years following OATS, and 54.07% of reoperations at 2 years following OCA (Figure 3, Tables 4–7).

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation; OR, operating room.

Abbreviations: CPT, Current Procedural Terminology; MFX, microfracture; OR, operating room.

^aA -1 denotes No. <11 within the PearlDiver database, and exact numbers are not reported due to patient privacy considerations.

Abbreviations: ACI, autologous chondrocyte implantation; CPT, Current Procedural Terminology; OR, operating room.

Abbreviations: CPT, Current Procedural Terminology; OATS, osteochondral autograft transplantation; OR, operating room.

Abbreviations: CPT, Current Procedural Terminology; OCA, osteochondral allograft; OR, operating room.

Continue to: Discussion...

DISCUSSION

The principle findings of this study demonstrate that there is an overall reoperation rate of 14.90% at 2 years following cartilage repair/restoration surgery, with the highest reoperation rates following MFX at 90 days, and ACI at both 1 year and 2 years following the index procedure. Also, patients undergoing index MFX as the index procedure have the highest risk for conversion to arthroplasty, reoperation rates for all cartilage surgeries increase over time, and arthroscopic chondroplasty is the most frequent procedure performed at the time of reoperation.

The management of symptomatic articular cartilage knee pathology is extremely challenging. With improvements in surgical technique, instrumentation, and clinical decision-making, indications are constantly evolving. Techniques that may work for “small” defects, though there is some debate as to what constitutes a “small” defect, are not necessarily going to be successful for larger defects, and this certainly varies depending on where the defect is located within the knee joint (distal femur vs patella vs trochlea, etc.). Recently, in a 2015 analysis of 3 level I or II studies, Miller and colleagues⁷ demonstrated both MFX and OATS to be viable, cost-effective, first-line treatment options for articular cartilage injuries, with similar clinical outcomes at 8.7 years. The authors noted cumulative reoperation rates of 29% among patients undergoing MFX compared to 13% among patients undergoing OATS. While ACI and OCA procedures were not included in their study, the reported reoperation rates of 29% following MFX and 13% following OATS at nearly 10 years suggest a possible increased need for reoperation following MFX over time (approximately 15% at 2 years in our study) and a stable rate of reoperation following OATS (approximately 11% at 2 years in our study). This finding is significant, as one of the goals with these procedures is to deliver effective, long-lasting pain relief and restoration of function. Interestingly, in this study, restorative OATS and OCA techniques were performed with the greatest frequency in the 15-year-old to 19-year-old age group, but were not performed in patients older than 64 years. This may be explained by the higher prevalence of acute traumatic injuries and osteochondritis dissecans diagnoses in younger patients compared with older patients, as these diagnoses are more often indicated to undergo restorative procedures as opposed to marrow stimulation.

In a 2016 systematic review of 20 studies incorporating 1117 patients, Campbell and colleagues⁸ assessed return-to-play rates following MFX, ACI, OATS, and OCA. The authors noted that return to sport (RTS) rates were greatest following OATS (89%), followed by OCA (88%), ACI (84%), and MFX (75%). Positive prognostic factors for RTS included younger age, shorter duration of preoperative symptoms, no history of prior ipsilateral knee surgery, and smaller chondral defects. Reoperation rates between the 4 techniques were not statistically compared in their study. Interestingly, in 2013, Chalmers and colleagues⁹ conducted a separate systematic review of 20 studies comprising 1375 patients undergoing MFX, ACI, or OATS. In their study, the authors found significant advantages following ACI and OATS compared to MFX with respect to patient-reported outcome scores but noted significantly faster RTS rates with MFX. Reoperation rates were noted to be similar between the 3 procedures (25% for ACI, 21% for MFX, and 28% for OATS) at an average 3.7 years following the index procedure. When considering these 2 systematic reviews together, despite a faster RTS rate following MFX, a greater proportion of patients seem to be able to RTS over time following other procedures such as OATS, OCA, and ACI. Unfortunately, these reviews do not provide insight as to the role, if any, of reoperation on return to play rates nor on overall clinical outcome scores on patients undergoing articular cartilage surgery. However, this information is valuable when counseling athletes who are in season and would like to RTS as soon as possible as opposed to those who do not have tight time constraints for when they need to RTS.

Regardless of the cartilage technique chosen, the goals of surgery remain similar—to reduce pain and improve function. For athletes, the ultimate goal is to return to the same level of play that the athlete was able to achieve prior to injury. Certainly, the need for reoperation following a cartilage surgery has implications on pain, function, and ability to RTS. Our review of nearly 50,000 cartilage surgeries demonstrates that reoperations following cartilage repair surgery are not uncommon, with a rate of 14.90% at 2 years, and that while reoperation rates are the highest following ACI, the rate of conversion to knee arthroplasty is highest following MFX. Due to the limitations of the PearlDiver database, it is not possible to determine the clinical outcomes of patients undergoing reoperation following cartilage surgery, but certainly, given these data, reoperation is clearly not necessarily indicative of clinical failure. This is highlighted by the fact that the most common procedure performed at the time of reoperation is arthroscopic chondroplasty, which, despite being an additional surgical procedure, may be acceptable for patients who wish to RTS, particularly in the setting of an index ACI in which there may be graft hypertrophy. Ideally, additional studies incorporating a cost-effectiveness analysis of each of the procedures, incorporating reoperation rates as well as patient-reported clinical outcomes, would be helpful to truly determine the patient and societal implications of reoperation following cartilage repair/restoration.

Many of the advantages and disadvantages of the described cartilage repair/restoration procedures have been well described.^10-17 Microfracture is the most commonly utilized first-line repair/restoration option for small articular cartilage lesions, mainly due to its low cost, low morbidity, and relatively low level of difficulty.18 Despite these advantages, MFX is not without limitations, and the need for revision cartilage restoration and/or conversion to arthroplasty is concerning. In 2013, Salzmann and colleagues19 evaluated a cohort of 454 patients undergoing MFX for a symptomatic knee defect and noted a reoperation rate of 26.9% (n = 123) within 2 years of the index surgery, with risk factors for reoperation noted to include an increased number of pre-MFX ipsilateral knee surgeries, patellofemoral lesions, smoking, and lower preoperative numeric analog scale scores. The definition of reoperation in their study is unfortunately not described, and thus the extent of reoperation (arthroscopy to arthroplasty) is unclear. In a 2009 systematic review of 3122 patients (28 studies) undergoing MFX conducted by Mithoefer and colleagues,²⁰ revision rates were noted to range from 2% to 31% depending on the study analyzed, with increasing revision rates after 2 years. Unfortunately, the heterogeneity of the included studies makes it difficult to determine which patients tend to fail over time.

Continue to: OATS...

OATS is a promising cartilage restoration technique indicated for treatment of patients with large, uncontained chondral lesions, and/or lesions with both bone and cartilage loss.¹ OCA is similar to OATS but uses allograft tissue instead of autograft tissue and is typically considered a viable treatment option in larger lesions (>2 cm²).²¹ Cell-based ACI therapy has evolved substantially over the past decade and is now available as a third-generation model utilizing biodegradable 3-dimensional scaffolds seeded with chondrocytes. Reoperation rates following ACI can often be higher than those following other cartilage treatments, particularly given the known complication of graft hypertrophy and/or delamination. Harris and colleagues²² conducted a systematic review of 5276 subjects undergoing ACI (all generations), noting an overall reoperation rate of 33%, but a failure rate of 5.8% at an average of 22 months following ACI. Risk factors for reoperation included periosteal-based ACI as well as open (vs arthroscopic) ACI. In this study, we found a modestly lower return to OR rate of 29.69% at 2 years.

When the outcomes of patients undergoing OATS or OCA are compared to those of patients undergoing MFX or ACI, it can be difficult to interpret the results, as the indications for performing these procedures tend to be very different. Further, the reasons for reoperation, as well as the procedures performed at the time of reoperation, are often poorly described, making it difficult to truly quantify the risk of reoperation and the implications of reoperation for patients undergoing any of these index cartilage procedures.

Overall, in this database, the return to the OR rate approaches 15% at 2 years following cartilage surgery, with cell-based therapy demonstrating higher reoperation rates at 2 years, without the risk of conversion to arthroplasty. Reoperation rates appear to stabilize at 1 year following surgery and consist mostly of minor arthroscopic procedures. These findings can help surgeons counsel patients as to the rate and type of reoperations that can be expected following cartilage surgery. Additional research incorporating patient-reported outcomes and patient-specific risk factors are needed to complement these data as to the impact of reoperations on overall clinical outcomes. Further, studies incorporating 90-day, 1-year, and 2-year costs associated with cartilage surgery will help to determine which index procedure is the most cost effective over the short- and long-term.

LIMITATIONS

This study is not without limitations. The PearlDiver database is reliant upon accurate CPT and ICD-9 coding, which creates a potential for a reporting bias. The overall reliability of the analyses is dependent on the quality of the available data, which, as noted in previous PearlDiver studies,^18,23-28 may include inaccurate billing codes, miscoding, and/or non-coding by physicians as potential sources of error. At the time of this study, the PearlDiver database did not provide consistent data points on laterality, and thus it is possible that the reported rates of reoperation overestimate the true reoperation rate following a given procedure. Fortunately, the reoperation rates for each procedure analyzed in this database study are consistent with those previously presented in the literature. In addition, it is not uncommon for patients receiving one of these procedures to have previously been treated with one of the others. Due to the inherent limitations of the PearlDiver database, this study did not investigate concomitant procedures performed along with the index procedure, nor did it investigate confounding factors such as comorbidities. The PearlDiver database does not provide data on defect size, location within the knee, concomitant pathologies (eg, meniscus tear), prior surgeries, or patient comorbidities, and while important, these factors cannot be accounted for in our analysis. The inability to account for these important factors, particularly concomitant diagnoses, procedures, and lesion size/location, represents an important limitation of this study, as this is a source of selection bias and may influence the need for reoperation in a given patient. Despite these limitations, the results of this study are supported by previous and current literature. In addition, the PearlDiver database, as a HIPAA-compliant database, does not report exact numbers when the value of the outcome of interest is between 0 and 10, which prohibits analysis of any cartilage procedure performed in a cohort of patients greater than 1 and less than 11. Finally, while not necessarily a limitation, it should be noted that CPT 29879 is not specific for microfracture, as the code also includes abrasion arthroplasty and drilling. Due to the limitations of the methodology of searching the database for this code, it is unclear as to how many patients underwent actual microfracture vs abrasion arthroplasty.

CONCLUSION

Within a large US commercial insurance database from 2007 to 2011, reparative procedures were favored for chondral injuries, but yielded an increased risk for conversion to arthroplasty. There was no difference between failure/revision rates among the restorative approaches, yet cell-based approaches yielded a significantly increased risk for a return to the OR.

ABSTRACT

The purpose of this study is to describe the rate of return to the operating room (OR) following microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and osteochondral allograft (OCA) procedures at 90 days, 1 year, and 2 years. Current Procedural Terminology codes for all patients undergoing MFX, ACI, OATS, and OCA were used to search a prospectively collected, commercially available private payer insurance company database from 2007 to 2011. Within 90 days, 1 year, and 2 years after surgery, the database was searched for the occurrence of these same patients undergoing knee diagnostic arthroscopy with biopsy, lysis of adhesions, synovectomy, arthroscopy for infection or lavage, arthroscopy for removal of loose bodies, chondroplasty, MFX, ACI, OATS, OCA, and/or knee arthroplasty. Descriptive statistical analysis and contingency table analysis were performed. A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX, 640 ACI, 386 open OATS, 997 arthroscopic OATS, 714 open OCA, and 894 arthroscopic OCA procedures. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. At 2 years, patients who underwent MFX, ACI, OATS, OCA had reoperation rates of 14.65%, 29.69%, 8.82%, and 12.22%, respectively. There was a statistically significantly increased risk for ACI return to OR within all intervals (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative treatment options. With a large US commercial insurance database from 2007 to 2011, reparative procedures were favored for chondral injuries, but yielded an increased risk for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative approaches, yet cell-based approaches yielded a significantly increased risk for a return to the OR.

Continue to: Symptomatic, full-thickness articular cartilage

Symptomatic, full-thickness articular cartilage defects in the knee are difficult to manage, particularly in the young, athletic patient population. Fortunately, a variety of cartilage repair (direct repair of the cartilage or those procedures which attempt to generate fibrocartilage) and restoration (those aimed at restoring hyaline cartilage) procedures are available, with encouraging short- and long-term clinical outcomes. After failure of nonoperative management, several surgical options are available for treating symptomatic focal chondral defects, including microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and open and arthroscopic osteochondral allograft (OCA) transplantation procedures.^1,2 When appropriately indicated, each of these techniques has demonstrated good to excellent clinical outcomes with respect to reducing pain and improving function.^3-5

While major complications following cartilage surgery are uncommon, the need for reoperation following an index articular cartilage operation is poorly understood. Recently, McCormick and colleagues6 found that reoperation within the first 2 years following meniscus allograft transplantation (MAT) is associated with an increased likelihood of revision MAT or future arthroplasty. Given the association between early reoperation following meniscus restoration surgery and subsequent failure, an improved understanding of the epidemiology and implications of reoperations following cartilage restoration surgery is warranted. Further, in deciding which treatment option is best suited to a particular patient, the rate of return to the operating room (OR) should be taken into consideration, as this could potentially influence surgical decision-making as to which procedure to perform, especially in value-based care decision-making environments.

The purpose of this study is to describe the rate of return to the OR for knee procedures following cartilage restoration at intervals of 90 days, 1 year, and 2 years across a large-scale US patient database. The authors hypothesize that the rate of return to the OR following knee cartilage repair or restoration procedures will be under 20% during the first post-operative year, with increasing reoperation rates over time. A secondary hypothesis is that there will be no difference in reoperation rates according to sex, but that younger patients (those younger than 40 years) will have higher reoperation rates than older patients.

METHODS

We performed a retrospective analysis of a prospectively collected, large-scale, and commercially available private payer insurance company database (PearlDiver) from 2007 to 2011. The PearlDiver database is a Health Insurance Portability and Accountability Act (HIPAA) compliant, publicly available national database consisting of a collection of private payer records, with United Health Group representing the contributing health plan. The database has more than 30 million patient records and contains Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9) codes related to orthopedic procedures. From 2007 to 2011, the private payer database captured between 5.9 million and 6.2 million patients per year.

Our search was based on the CPT codes for MFX (29879), ACI (27412), OATS (29866, 29867), and OCA (27415, 27416). Return to the OR for revision surgery for the above-mentioned procedures was classified as patients with a diagnosis of diagnostic arthroscopy with biopsy (CPT 29870), lysis of adhesions (CPT 29884), synovectomy (29875, 29876), arthroscopy for infection or lavage (CPT 29871), arthroscopy for removal of loose bodies (29874), chondroplasty (29877), unicompartmental knee arthroplasty (27446), total knee arthroplasty (27447), and/or patellar arthroplasty (27438). Patient records were followed for reoperations occurring within 90 days, 1 year, and 2 years after the index cartilage procedure. All data were compared based on patient age and sex.

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation.

Continue to: Statistical analysis...

STATISTICAL ANALYSIS

Statistical analysis of this study was primarily descriptive to demonstrate the incidence for each code at each time interval. One-way analysis of variance, Chi-square analysis, and contingency tables were used to compare the incidence of each type of procedure throughout the various time intervals. A P-value of < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS v.20 (International Business Machines).

RESULTS

A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX (92.3%) 640 ACI (1.4%), 386 open OATS (0.82%), 997 arthroscopic OATS (2.11%), 714 open OCA (1.51%), and 894 arthroscopic OCA (1.89%) procedures. A summary of the procedures performed, broken down by age and sex, is provided in Tables 1 and 2. A total of 25,149 male patients (53.3%) underwent surgical procedures compared to 22,058 female patients (46.7%). For each category of procedure (MFX, ACI, OATS, OCA), there was a significantly higher proportion of males than females undergoing surgery (P < .0001 for all). Surgical treatment with MFX was consistently the most frequently performed surgery across all age groups (92.31%), while cell-based therapy with ACI was the least frequently performed procedure across all age ranges (1.36%). Restorative OATS and OCA techniques were performed with the greatest frequency in the 15-year-old to 19-year-old age group, but were not utilized in patients over 64 years of age (Table 2).

Abbreviations: ACI, autologous chondrocyte implantation; MFX, microfracture; OCA, osteochondral allograft; OATS, osteochondral autograft transplantation.

A summary of all reoperation data is provided in Tables 3 to 7 and Figures 1 and 2. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. Patients who underwent MFX had reoperation rates of 6.05% at 90 days, 11.80% at 1 year, and 14.65% at 2 years. Patients who underwent ACI had reoperation rates of 4.53% at 90 days, 23.28% at 1 year, and 29.69% at 2 years. Patients who had open and arthroscopic OATS had reoperation rates of 3.122% and 5.12% at 90 days, 6.74% and 8.53% at 1 year, and 7.51% and 10.13% at 2 years, respectively. Patients who underwent open and arthroscopic OCA had reoperation rates of 2.52% and 3.91% at 90 days, 7.14% and 6.60% at 1 year, and 13.59% and 10.85% at 2 years (Table 3). There was a statistically significantly increased risk for reoperation following ACI within all intervals compared to all other surgical techniques (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty at 6.70%. There was no significant difference between failure rates (revision OATS/OCA or conversion to arthroplasty) between the restorative treatment options, with 14 failures for OATS (9.52% of reoperations at 2 years) compared to 22 failures for OCA (12.7% of reoperations at 2 years, P = .358). Among the entire cohort of cartilage surgery patients, arthroscopic chondroplasty was the most frequent procedure performed at the time of reoperation at all time points assessed, notably accounting for 33.08% of reoperations 2 years following microfracture, 51.58% of reoperations at 2 years following ACI, 53.06% of reoperations at 2 years following OATS, and 54.07% of reoperations at 2 years following OCA (Figure 3, Tables 4–7).