Gift Ukwuani, MD

ABSTRACT

Antegrade reamed intramedullary nailing has the advantages of high fracture union and early weight-bearing, making it the gold standard for fixation of diaphyseal femur fractures. However, knowledge of distal femoral anatomy may mitigate the risk of secondary complications.

We present a previously unrecognized complication of antegrade femoral nailing in which a 23-year-old man sustained iatrogenic rupture of the medial patellofemoral ligament (MPFL) caused by the distal interlocking screw of the femoral nail. The patient had a history of antegrade intramedullary nailing that was revised for rotational malalignment, after which he began experiencing recurrent episodes of atraumatic bloody joint effusion and swelling of the right knee with associated patellar instability. Plain radiographs and magnetic resonance imaging revealed a large effusion with a prominent intra-articular distal interlocking screw disrupting the MPFL. The patient underwent a right knee arthroscopic-assisted MPFL reconstruction and removal of the distal interlocking screw. Following surgery, the patient experienced resolution of his effusions, no recurrent patellar instability, and was able to return to his activities.

This case demonstrates that iatrogenic MPFL injury is a potential complication of antegrade femoral nailing and a previously unrecognized cause of patellar instability. Surgeons should be aware of this potential complication and strive to avoid the MPFL origin when placing their distal interlocking screw.

Continue to: Reamed intramedullary nails...

Reamed intramedullary nails are the gold standard for fixation of femoral diaphyseal fractures.¹ Antegrade or retrograde nails are effective options, with the choice of technique based on factors including surgeon preference, patient factors, and concomitant injuries.² Interlocking screws are generally placed to allow control of both rotation and length.¹ Advantages of intramedullary treatment of femoral diaphyseal fractures compared with plate fixation include low rates of infection, lower nonunion rate, and faster patient mobilization and weight-bearing.³

Complications of antegrade intramedullary fixation of femoral shaft fractures include infection, nonunion, malunion, anterior cortical perforation, heterotopic ossification, abductor weakness, and soft tissue irritation from interlocking screws.^2-4 Femoral intramedullary nails are not routinely removed because the hardware is rarely symptomatic and removing the nail involves additional surgical morbidity with the potential for complications.⁵ Interlocking screws are removed in select cases due to soft tissue irritation, generally after fracture union. Although hardware removal may help in select cases, removal of intramedullary nails is associated with low rates of symptom resolution.^6-8

We present a case of iatrogenic medial patellofemoral ligament (MPFL) disruption by the distal interlocking screw leading to patellar instability, a previously unrecognized complication of antegrade femoral nailing for femoral diaphyseal fractures. The patient provided written informed consent for print and electronic publication of this case report.

CASE REPORT

We present a case of a 23-year-old man whose status was 2 years post antegrade reamed femoral intramedullary nailing at an outside institution for a right diaphyseal femur fracture. This issue was revised for external rotational malalignment, and he presented with right anterior knee pain, recurrent patellar subluxation, and recurrent effusions. The extent of external rotational malalignment and subsequent rotational correction were not evident from the available outside institution records. These symptoms began after his femoral nail revision for malalignment, and he had no subsequent trauma. The femoral fracture healed uneventfully. The patient denied any history of knee pain, swelling, or patellar instability before his femoral nail revision for malalignment. These episodes of effusion, instability, and pain occurred several times per year, generally with activities of daily living (ADL). On one occasion, he presented to a local emergency room where knee aspiration revealed no evidence of crystals or infection. The patient was referred to the senior author (Dr. Nho) for consultation.

Physical examination revealed right knee full extension with flexion to 80°. A moderate right knee effusion was present. The patient was tender over the medial femoral epicondyle and the superomedial aspect of the patella without joint line tenderness. Lateral patellar instability was present with 2 quadrants of translation (compared with 1 on the contralateral side) and patellar apprehension. The patient’s knee was ligamentously stable, and meniscal signs were absent. His lower extremity rotational profile was symmetric to the contralateral uninjured side.

Right femur and knee X-rays showed an antegrade intramedullary nail with a well-healed diaphyseal fracture and a single distal interlocking screw oriented from posterolateral to anteromedial (Figures 1A-1G). The screw tip was prominent on sunrise X-ray view anterior to the medial femoral epicondyle (Figure 1C). Magnetic resonance imaging demonstrated a large effusion and lateral patellar subluxation with a prominent intra-articular distal interlocking screw disrupting the MPFL near the femoral attachment (Figure 2). Patellar height, trochlear morphology, and tibial tubercle-trochlear groove distance were assessed and found to be normal.

Continue to: The patient elected...

The patient elected to have a right knee arthroscopic-assisted MPFL reconstruction and removal of the distal interlocking screw. Diagnostic arthroscopy revealed the distal interlocking screw to be intra-articular medially, prominent by 3 mm causing attritional disruption of the mid-substance MPFL (Figure 3A). The patella was noted to be subluxated and tracking laterally (Figure 3B). Both the anterior cruciate ligament and posterior cruciate ligament were intact, and menisci and articular cartilage were normal. The distal interlocking screw was removed under fluoroscopic guidance through a small lateral incision (Figure 3C).

Due to the nature of the longstanding attritional disruption of the MPFL in this case with associated patellar instability over a 2-year period, the decision was made to proceed with formal MPFL reconstruction as opposed to repair. A 2-cm incision was made at the medial aspect of the patella. The proximal half of the patella was decorticated. Guide pins were placed within the proximal half of the patella, ensuring at least a 1-cm bone bridge between them, and two 4.75-mm SwiveLock suture anchors (Arthrex) were inserted. A semitendinosus graft was used for MPFL reconstruction with the 2 ends of the graft secured to 2 suture anchors with a whipstitch. Lateral fluoroscopy was used to identify Schöttle’s point, denoting the femoral origin of the MPFL⁹ (Figure 3D). A 2-cm incision was made at this location. A guide pin was then placed at Schöttle’s point under fluoroscopic guidance, aimed proximally, and the knee was brought through a range of motion (ROM), to verify graft isometry. Once verified, the guide pin was over-reamed to 8 mm. The layer between the retinaculum and the capsule was carefully dissected, and the graft was passed extra-articularly in the plane between the retinaculum and the capsule, out through the medial incision, and docked into the bone tunnel. An 8-mm BioComposite interference screw (Arthrex) was then placed with the knee flexed to 30°. The knee was then passed through a ROM and an arthroscopic evaluation confirmed that the patella was no longer subluxated laterally. There was normal tracking of the patellofemoral joint on arthroscopic evaluation.

Postoperatively, the patient was maintained in a hinged knee brace for 6 weeks. He was weight-bearing as tolerated when locked in full extension beginning immediately postoperatively, and allowed to unlock the brace to start non-weight-bearing active flexion and extension with therapy on postoperative day 1. Radiographs confirmed removal of the distal interlocking screw (Figures 4A, 4B). Following surgery, the patient experienced resolution of his effusions, no recurrent patellar instability at 1-year postoperative, and was able to return to his ADL and recreational sporting activities (Knee Injury and Osteoarthritis Outcome Score [KOOS] ADL, 100; KOOS sporting and recreational activities, 95; quality of life, 100; Marx Activity Rating Scale, 12).

DISCUSSION

The MPFL connects the superomedial edge of the patella to the medial femur and is injured in nearly 100% of patellar dislocations.⁶ The femoral origin lies between the adductor tubercle and the medial epicondyle.⁷ The MPFL prevents lateral subluxation of the patella and acts as the major restraint during the first 20° of knee flexion. Although radiographic parameters for identifying the MPFL femoral origin have been defined by both Schöttle and colleagues⁹ and Stephen and colleagues¹⁰, it is important to check the isometry intraoperatively through a ROM when performing MPFL reconstruction. In this case, the patient’s history and physical examination showed patellar instability, which was determined to be iatrogenically related to the distal interlocking screw rupture of the MPFL. Following screw removal and MPFL reconstruction, the patient had no further symptoms of pain, effusion, or patellar instability and returned to his normal activities.

Femoral malrotation following intramedullary nailing of femoral shaft fractures is a common complication,⁴ with a 22% incidence of malrotation of at least 15° in 1 series from an academic trauma center.¹¹ There are mixed data as to whether malrotation is more common in complex fracture patterns, in cases performed during night hours, and in cases performed by non-trauma fellowship-trained surgeons.^11-13 The natural history of malrotation is not well elucidated, but there is some suggestion that it alters load bearing in the distal joints of the involved leg including the patellofemoral joint. Patients also may not tolerate malrotation due to the abnormal foot progression angle, particularly with malrotation >15°.⁴ In this case, the patient’s initial femoral nail was placed in an externally rotated position, requiring revision. The result of this was an unusual trajectory of the distal interlocking screw from posterolateral to anteromedial. Combined with the prominent screw tip, the trajectory of this distal interlocking screw likely contributed to the injury to the MPFL observed in this case. This trajectory would also pose potential risk to the common peroneal nerve, which is usually situated posterior to the insertion point for distal femoral interlocking screws. The prominent distal interlock screw is a well-recognized problem with femoral intramedullary nails. This issue results from the tapering of the width of the distal femur from being larger posteriorly to being smaller anteriorly. To avoid placement of a prominent distal interlocking screw, surgeons often will obtain an intraoperative anterior-posterior radiograph with the lower extremity in 30° of internal rotation to account for the angle of the medial aspect of the distal femur.

This practice represents, to our knowledge, a previously unreported cause of patellar instability as well as an unreported complication of antegrade femoral intramedullary nailing. Surgeons treating these conditions should consider this potential complication and pursue advanced imaging if patients present with these complaints after femoral intramedullary nail placement. Knowledge of both MPFL origin and insertional anatomy and avoidance of prominent distal interlocking screws in the region of the MPFL, if possible, would likely prevent this complication.

Limitations of this study include the case report design, which makes it impossible to comment on the incidence of this complication or to make comparisons regarding treatment options. There is, of course, the possibility that the patient had a concurrent MPFL injury from the injury in which he sustained the femur fracture. Nevertheless, the clinical history, examination, imaging, and arthroscopic findings all strongly suggest that the prominent distal interlocking screw was the cause of his MPFL injury and patellar instability. Finally, the point widely defined by Schöttle and colleagues¹² was used for MPFL reconstruction in this case based on an intraoperative true lateral radiograph of the distal femur. It should be noted that recent literature has debated the accuracy of this method for determining the femoral origin, the anatomy of the MPFL in relation to the quadriceps, and type of fixation for MPFL reconstruction with some advocating soft tissue only fixation.^14-17 For purposes of this case report, we focused on a different cause of MPFL disruption in this patient and our technique for MPFL reconstruction.

CONCLUSION

This case demonstrates that iatrogenic MPFL injury is a potential complication of antegrade femoral nailing and a previously unrecognized cause of patellar instability. Surgeons should be aware of this potential complication and strive to avoid the MPFL origin when placing their distal interlocking screw.

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

ABSTRACT

Antegrade reamed intramedullary nailing has the advantages of high fracture union and early weight-bearing, making it the gold standard for fixation of diaphyseal femur fractures. However, knowledge of distal femoral anatomy may mitigate the risk of secondary complications.

We present a previously unrecognized complication of antegrade femoral nailing in which a 23-year-old man sustained iatrogenic rupture of the medial patellofemoral ligament (MPFL) caused by the distal interlocking screw of the femoral nail. The patient had a history of antegrade intramedullary nailing that was revised for rotational malalignment, after which he began experiencing recurrent episodes of atraumatic bloody joint effusion and swelling of the right knee with associated patellar instability. Plain radiographs and magnetic resonance imaging revealed a large effusion with a prominent intra-articular distal interlocking screw disrupting the MPFL. The patient underwent a right knee arthroscopic-assisted MPFL reconstruction and removal of the distal interlocking screw. Following surgery, the patient experienced resolution of his effusions, no recurrent patellar instability, and was able to return to his activities.

This case demonstrates that iatrogenic MPFL injury is a potential complication of antegrade femoral nailing and a previously unrecognized cause of patellar instability. Surgeons should be aware of this potential complication and strive to avoid the MPFL origin when placing their distal interlocking screw.

Continue to: Reamed intramedullary nails...

Reamed intramedullary nails are the gold standard for fixation of femoral diaphyseal fractures.¹ Antegrade or retrograde nails are effective options, with the choice of technique based on factors including surgeon preference, patient factors, and concomitant injuries.² Interlocking screws are generally placed to allow control of both rotation and length.¹ Advantages of intramedullary treatment of femoral diaphyseal fractures compared with plate fixation include low rates of infection, lower nonunion rate, and faster patient mobilization and weight-bearing.³

Complications of antegrade intramedullary fixation of femoral shaft fractures include infection, nonunion, malunion, anterior cortical perforation, heterotopic ossification, abductor weakness, and soft tissue irritation from interlocking screws.^2-4 Femoral intramedullary nails are not routinely removed because the hardware is rarely symptomatic and removing the nail involves additional surgical morbidity with the potential for complications.⁵ Interlocking screws are removed in select cases due to soft tissue irritation, generally after fracture union. Although hardware removal may help in select cases, removal of intramedullary nails is associated with low rates of symptom resolution.^6-8

We present a case of iatrogenic medial patellofemoral ligament (MPFL) disruption by the distal interlocking screw leading to patellar instability, a previously unrecognized complication of antegrade femoral nailing for femoral diaphyseal fractures. The patient provided written informed consent for print and electronic publication of this case report.

CASE REPORT

We present a case of a 23-year-old man whose status was 2 years post antegrade reamed femoral intramedullary nailing at an outside institution for a right diaphyseal femur fracture. This issue was revised for external rotational malalignment, and he presented with right anterior knee pain, recurrent patellar subluxation, and recurrent effusions. The extent of external rotational malalignment and subsequent rotational correction were not evident from the available outside institution records. These symptoms began after his femoral nail revision for malalignment, and he had no subsequent trauma. The femoral fracture healed uneventfully. The patient denied any history of knee pain, swelling, or patellar instability before his femoral nail revision for malalignment. These episodes of effusion, instability, and pain occurred several times per year, generally with activities of daily living (ADL). On one occasion, he presented to a local emergency room where knee aspiration revealed no evidence of crystals or infection. The patient was referred to the senior author (Dr. Nho) for consultation.

Physical examination revealed right knee full extension with flexion to 80°. A moderate right knee effusion was present. The patient was tender over the medial femoral epicondyle and the superomedial aspect of the patella without joint line tenderness. Lateral patellar instability was present with 2 quadrants of translation (compared with 1 on the contralateral side) and patellar apprehension. The patient’s knee was ligamentously stable, and meniscal signs were absent. His lower extremity rotational profile was symmetric to the contralateral uninjured side.

Right femur and knee X-rays showed an antegrade intramedullary nail with a well-healed diaphyseal fracture and a single distal interlocking screw oriented from posterolateral to anteromedial (Figures 1A-1G). The screw tip was prominent on sunrise X-ray view anterior to the medial femoral epicondyle (Figure 1C). Magnetic resonance imaging demonstrated a large effusion and lateral patellar subluxation with a prominent intra-articular distal interlocking screw disrupting the MPFL near the femoral attachment (Figure 2). Patellar height, trochlear morphology, and tibial tubercle-trochlear groove distance were assessed and found to be normal.

Continue to: The patient elected...

The patient elected to have a right knee arthroscopic-assisted MPFL reconstruction and removal of the distal interlocking screw. Diagnostic arthroscopy revealed the distal interlocking screw to be intra-articular medially, prominent by 3 mm causing attritional disruption of the mid-substance MPFL (Figure 3A). The patella was noted to be subluxated and tracking laterally (Figure 3B). Both the anterior cruciate ligament and posterior cruciate ligament were intact, and menisci and articular cartilage were normal. The distal interlocking screw was removed under fluoroscopic guidance through a small lateral incision (Figure 3C).

Due to the nature of the longstanding attritional disruption of the MPFL in this case with associated patellar instability over a 2-year period, the decision was made to proceed with formal MPFL reconstruction as opposed to repair. A 2-cm incision was made at the medial aspect of the patella. The proximal half of the patella was decorticated. Guide pins were placed within the proximal half of the patella, ensuring at least a 1-cm bone bridge between them, and two 4.75-mm SwiveLock suture anchors (Arthrex) were inserted. A semitendinosus graft was used for MPFL reconstruction with the 2 ends of the graft secured to 2 suture anchors with a whipstitch. Lateral fluoroscopy was used to identify Schöttle’s point, denoting the femoral origin of the MPFL⁹ (Figure 3D). A 2-cm incision was made at this location. A guide pin was then placed at Schöttle’s point under fluoroscopic guidance, aimed proximally, and the knee was brought through a range of motion (ROM), to verify graft isometry. Once verified, the guide pin was over-reamed to 8 mm. The layer between the retinaculum and the capsule was carefully dissected, and the graft was passed extra-articularly in the plane between the retinaculum and the capsule, out through the medial incision, and docked into the bone tunnel. An 8-mm BioComposite interference screw (Arthrex) was then placed with the knee flexed to 30°. The knee was then passed through a ROM and an arthroscopic evaluation confirmed that the patella was no longer subluxated laterally. There was normal tracking of the patellofemoral joint on arthroscopic evaluation.

Postoperatively, the patient was maintained in a hinged knee brace for 6 weeks. He was weight-bearing as tolerated when locked in full extension beginning immediately postoperatively, and allowed to unlock the brace to start non-weight-bearing active flexion and extension with therapy on postoperative day 1. Radiographs confirmed removal of the distal interlocking screw (Figures 4A, 4B). Following surgery, the patient experienced resolution of his effusions, no recurrent patellar instability at 1-year postoperative, and was able to return to his ADL and recreational sporting activities (Knee Injury and Osteoarthritis Outcome Score [KOOS] ADL, 100; KOOS sporting and recreational activities, 95; quality of life, 100; Marx Activity Rating Scale, 12).

DISCUSSION

The MPFL connects the superomedial edge of the patella to the medial femur and is injured in nearly 100% of patellar dislocations.⁶ The femoral origin lies between the adductor tubercle and the medial epicondyle.⁷ The MPFL prevents lateral subluxation of the patella and acts as the major restraint during the first 20° of knee flexion. Although radiographic parameters for identifying the MPFL femoral origin have been defined by both Schöttle and colleagues⁹ and Stephen and colleagues¹⁰, it is important to check the isometry intraoperatively through a ROM when performing MPFL reconstruction. In this case, the patient’s history and physical examination showed patellar instability, which was determined to be iatrogenically related to the distal interlocking screw rupture of the MPFL. Following screw removal and MPFL reconstruction, the patient had no further symptoms of pain, effusion, or patellar instability and returned to his normal activities.

Femoral malrotation following intramedullary nailing of femoral shaft fractures is a common complication,⁴ with a 22% incidence of malrotation of at least 15° in 1 series from an academic trauma center.¹¹ There are mixed data as to whether malrotation is more common in complex fracture patterns, in cases performed during night hours, and in cases performed by non-trauma fellowship-trained surgeons.^11-13 The natural history of malrotation is not well elucidated, but there is some suggestion that it alters load bearing in the distal joints of the involved leg including the patellofemoral joint. Patients also may not tolerate malrotation due to the abnormal foot progression angle, particularly with malrotation >15°.⁴ In this case, the patient’s initial femoral nail was placed in an externally rotated position, requiring revision. The result of this was an unusual trajectory of the distal interlocking screw from posterolateral to anteromedial. Combined with the prominent screw tip, the trajectory of this distal interlocking screw likely contributed to the injury to the MPFL observed in this case. This trajectory would also pose potential risk to the common peroneal nerve, which is usually situated posterior to the insertion point for distal femoral interlocking screws. The prominent distal interlock screw is a well-recognized problem with femoral intramedullary nails. This issue results from the tapering of the width of the distal femur from being larger posteriorly to being smaller anteriorly. To avoid placement of a prominent distal interlocking screw, surgeons often will obtain an intraoperative anterior-posterior radiograph with the lower extremity in 30° of internal rotation to account for the angle of the medial aspect of the distal femur.

This practice represents, to our knowledge, a previously unreported cause of patellar instability as well as an unreported complication of antegrade femoral intramedullary nailing. Surgeons treating these conditions should consider this potential complication and pursue advanced imaging if patients present with these complaints after femoral intramedullary nail placement. Knowledge of both MPFL origin and insertional anatomy and avoidance of prominent distal interlocking screws in the region of the MPFL, if possible, would likely prevent this complication.

Limitations of this study include the case report design, which makes it impossible to comment on the incidence of this complication or to make comparisons regarding treatment options. There is, of course, the possibility that the patient had a concurrent MPFL injury from the injury in which he sustained the femur fracture. Nevertheless, the clinical history, examination, imaging, and arthroscopic findings all strongly suggest that the prominent distal interlocking screw was the cause of his MPFL injury and patellar instability. Finally, the point widely defined by Schöttle and colleagues¹² was used for MPFL reconstruction in this case based on an intraoperative true lateral radiograph of the distal femur. It should be noted that recent literature has debated the accuracy of this method for determining the femoral origin, the anatomy of the MPFL in relation to the quadriceps, and type of fixation for MPFL reconstruction with some advocating soft tissue only fixation.^14-17 For purposes of this case report, we focused on a different cause of MPFL disruption in this patient and our technique for MPFL reconstruction.

CONCLUSION

This case demonstrates that iatrogenic MPFL injury is a potential complication of antegrade femoral nailing and a previously unrecognized cause of patellar instability. Surgeons should be aware of this potential complication and strive to avoid the MPFL origin when placing their distal interlocking screw.

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

ABSTRACT

Antegrade reamed intramedullary nailing has the advantages of high fracture union and early weight-bearing, making it the gold standard for fixation of diaphyseal femur fractures. However, knowledge of distal femoral anatomy may mitigate the risk of secondary complications.

We present a previously unrecognized complication of antegrade femoral nailing in which a 23-year-old man sustained iatrogenic rupture of the medial patellofemoral ligament (MPFL) caused by the distal interlocking screw of the femoral nail. The patient had a history of antegrade intramedullary nailing that was revised for rotational malalignment, after which he began experiencing recurrent episodes of atraumatic bloody joint effusion and swelling of the right knee with associated patellar instability. Plain radiographs and magnetic resonance imaging revealed a large effusion with a prominent intra-articular distal interlocking screw disrupting the MPFL. The patient underwent a right knee arthroscopic-assisted MPFL reconstruction and removal of the distal interlocking screw. Following surgery, the patient experienced resolution of his effusions, no recurrent patellar instability, and was able to return to his activities.

This case demonstrates that iatrogenic MPFL injury is a potential complication of antegrade femoral nailing and a previously unrecognized cause of patellar instability. Surgeons should be aware of this potential complication and strive to avoid the MPFL origin when placing their distal interlocking screw.

Continue to: Reamed intramedullary nails...

Reamed intramedullary nails are the gold standard for fixation of femoral diaphyseal fractures.¹ Antegrade or retrograde nails are effective options, with the choice of technique based on factors including surgeon preference, patient factors, and concomitant injuries.² Interlocking screws are generally placed to allow control of both rotation and length.¹ Advantages of intramedullary treatment of femoral diaphyseal fractures compared with plate fixation include low rates of infection, lower nonunion rate, and faster patient mobilization and weight-bearing.³

Complications of antegrade intramedullary fixation of femoral shaft fractures include infection, nonunion, malunion, anterior cortical perforation, heterotopic ossification, abductor weakness, and soft tissue irritation from interlocking screws.^2-4 Femoral intramedullary nails are not routinely removed because the hardware is rarely symptomatic and removing the nail involves additional surgical morbidity with the potential for complications.⁵ Interlocking screws are removed in select cases due to soft tissue irritation, generally after fracture union. Although hardware removal may help in select cases, removal of intramedullary nails is associated with low rates of symptom resolution.^6-8

We present a case of iatrogenic medial patellofemoral ligament (MPFL) disruption by the distal interlocking screw leading to patellar instability, a previously unrecognized complication of antegrade femoral nailing for femoral diaphyseal fractures. The patient provided written informed consent for print and electronic publication of this case report.

CASE REPORT

We present a case of a 23-year-old man whose status was 2 years post antegrade reamed femoral intramedullary nailing at an outside institution for a right diaphyseal femur fracture. This issue was revised for external rotational malalignment, and he presented with right anterior knee pain, recurrent patellar subluxation, and recurrent effusions. The extent of external rotational malalignment and subsequent rotational correction were not evident from the available outside institution records. These symptoms began after his femoral nail revision for malalignment, and he had no subsequent trauma. The femoral fracture healed uneventfully. The patient denied any history of knee pain, swelling, or patellar instability before his femoral nail revision for malalignment. These episodes of effusion, instability, and pain occurred several times per year, generally with activities of daily living (ADL). On one occasion, he presented to a local emergency room where knee aspiration revealed no evidence of crystals or infection. The patient was referred to the senior author (Dr. Nho) for consultation.

Physical examination revealed right knee full extension with flexion to 80°. A moderate right knee effusion was present. The patient was tender over the medial femoral epicondyle and the superomedial aspect of the patella without joint line tenderness. Lateral patellar instability was present with 2 quadrants of translation (compared with 1 on the contralateral side) and patellar apprehension. The patient’s knee was ligamentously stable, and meniscal signs were absent. His lower extremity rotational profile was symmetric to the contralateral uninjured side.

Right femur and knee X-rays showed an antegrade intramedullary nail with a well-healed diaphyseal fracture and a single distal interlocking screw oriented from posterolateral to anteromedial (Figures 1A-1G). The screw tip was prominent on sunrise X-ray view anterior to the medial femoral epicondyle (Figure 1C). Magnetic resonance imaging demonstrated a large effusion and lateral patellar subluxation with a prominent intra-articular distal interlocking screw disrupting the MPFL near the femoral attachment (Figure 2). Patellar height, trochlear morphology, and tibial tubercle-trochlear groove distance were assessed and found to be normal.

Continue to: The patient elected...

The patient elected to have a right knee arthroscopic-assisted MPFL reconstruction and removal of the distal interlocking screw. Diagnostic arthroscopy revealed the distal interlocking screw to be intra-articular medially, prominent by 3 mm causing attritional disruption of the mid-substance MPFL (Figure 3A). The patella was noted to be subluxated and tracking laterally (Figure 3B). Both the anterior cruciate ligament and posterior cruciate ligament were intact, and menisci and articular cartilage were normal. The distal interlocking screw was removed under fluoroscopic guidance through a small lateral incision (Figure 3C).

Due to the nature of the longstanding attritional disruption of the MPFL in this case with associated patellar instability over a 2-year period, the decision was made to proceed with formal MPFL reconstruction as opposed to repair. A 2-cm incision was made at the medial aspect of the patella. The proximal half of the patella was decorticated. Guide pins were placed within the proximal half of the patella, ensuring at least a 1-cm bone bridge between them, and two 4.75-mm SwiveLock suture anchors (Arthrex) were inserted. A semitendinosus graft was used for MPFL reconstruction with the 2 ends of the graft secured to 2 suture anchors with a whipstitch. Lateral fluoroscopy was used to identify Schöttle’s point, denoting the femoral origin of the MPFL⁹ (Figure 3D). A 2-cm incision was made at this location. A guide pin was then placed at Schöttle’s point under fluoroscopic guidance, aimed proximally, and the knee was brought through a range of motion (ROM), to verify graft isometry. Once verified, the guide pin was over-reamed to 8 mm. The layer between the retinaculum and the capsule was carefully dissected, and the graft was passed extra-articularly in the plane between the retinaculum and the capsule, out through the medial incision, and docked into the bone tunnel. An 8-mm BioComposite interference screw (Arthrex) was then placed with the knee flexed to 30°. The knee was then passed through a ROM and an arthroscopic evaluation confirmed that the patella was no longer subluxated laterally. There was normal tracking of the patellofemoral joint on arthroscopic evaluation.

Postoperatively, the patient was maintained in a hinged knee brace for 6 weeks. He was weight-bearing as tolerated when locked in full extension beginning immediately postoperatively, and allowed to unlock the brace to start non-weight-bearing active flexion and extension with therapy on postoperative day 1. Radiographs confirmed removal of the distal interlocking screw (Figures 4A, 4B). Following surgery, the patient experienced resolution of his effusions, no recurrent patellar instability at 1-year postoperative, and was able to return to his ADL and recreational sporting activities (Knee Injury and Osteoarthritis Outcome Score [KOOS] ADL, 100; KOOS sporting and recreational activities, 95; quality of life, 100; Marx Activity Rating Scale, 12).

DISCUSSION

The MPFL connects the superomedial edge of the patella to the medial femur and is injured in nearly 100% of patellar dislocations.⁶ The femoral origin lies between the adductor tubercle and the medial epicondyle.⁷ The MPFL prevents lateral subluxation of the patella and acts as the major restraint during the first 20° of knee flexion. Although radiographic parameters for identifying the MPFL femoral origin have been defined by both Schöttle and colleagues⁹ and Stephen and colleagues¹⁰, it is important to check the isometry intraoperatively through a ROM when performing MPFL reconstruction. In this case, the patient’s history and physical examination showed patellar instability, which was determined to be iatrogenically related to the distal interlocking screw rupture of the MPFL. Following screw removal and MPFL reconstruction, the patient had no further symptoms of pain, effusion, or patellar instability and returned to his normal activities.

Femoral malrotation following intramedullary nailing of femoral shaft fractures is a common complication,⁴ with a 22% incidence of malrotation of at least 15° in 1 series from an academic trauma center.¹¹ There are mixed data as to whether malrotation is more common in complex fracture patterns, in cases performed during night hours, and in cases performed by non-trauma fellowship-trained surgeons.^11-13 The natural history of malrotation is not well elucidated, but there is some suggestion that it alters load bearing in the distal joints of the involved leg including the patellofemoral joint. Patients also may not tolerate malrotation due to the abnormal foot progression angle, particularly with malrotation >15°.⁴ In this case, the patient’s initial femoral nail was placed in an externally rotated position, requiring revision. The result of this was an unusual trajectory of the distal interlocking screw from posterolateral to anteromedial. Combined with the prominent screw tip, the trajectory of this distal interlocking screw likely contributed to the injury to the MPFL observed in this case. This trajectory would also pose potential risk to the common peroneal nerve, which is usually situated posterior to the insertion point for distal femoral interlocking screws. The prominent distal interlock screw is a well-recognized problem with femoral intramedullary nails. This issue results from the tapering of the width of the distal femur from being larger posteriorly to being smaller anteriorly. To avoid placement of a prominent distal interlocking screw, surgeons often will obtain an intraoperative anterior-posterior radiograph with the lower extremity in 30° of internal rotation to account for the angle of the medial aspect of the distal femur.

This practice represents, to our knowledge, a previously unreported cause of patellar instability as well as an unreported complication of antegrade femoral intramedullary nailing. Surgeons treating these conditions should consider this potential complication and pursue advanced imaging if patients present with these complaints after femoral intramedullary nail placement. Knowledge of both MPFL origin and insertional anatomy and avoidance of prominent distal interlocking screws in the region of the MPFL, if possible, would likely prevent this complication.

Limitations of this study include the case report design, which makes it impossible to comment on the incidence of this complication or to make comparisons regarding treatment options. There is, of course, the possibility that the patient had a concurrent MPFL injury from the injury in which he sustained the femur fracture. Nevertheless, the clinical history, examination, imaging, and arthroscopic findings all strongly suggest that the prominent distal interlocking screw was the cause of his MPFL injury and patellar instability. Finally, the point widely defined by Schöttle and colleagues¹² was used for MPFL reconstruction in this case based on an intraoperative true lateral radiograph of the distal femur. It should be noted that recent literature has debated the accuracy of this method for determining the femoral origin, the anatomy of the MPFL in relation to the quadriceps, and type of fixation for MPFL reconstruction with some advocating soft tissue only fixation.^14-17 For purposes of this case report, we focused on a different cause of MPFL disruption in this patient and our technique for MPFL reconstruction.

CONCLUSION

This case demonstrates that iatrogenic MPFL injury is a potential complication of antegrade femoral nailing and a previously unrecognized cause of patellar instability. Surgeons should be aware of this potential complication and strive to avoid the MPFL origin when placing their distal interlocking screw.

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

Take-Home Points

• Hip capsule provides static stabilization for the hip joint.
• Capsular management must weigh visualization to address underlying osseous deformity but also repair/plication of the capsule to maintain biomechanical characteristics.
• T-capsulotomy provides optimal visualization with a small interportal incision with a vertical incision along the femoral neck.
• Extensile interportal capsulotomy is the most widely used capsulotomy and size may vary depending on capsular and patient characteristics.
• Orthopedic surgeons should be equipped to employ either technique depending on the patients individual hip pathomorphology.

Hip arthroscopy has emerged as a common surgical treatment for a number of hip pathologies. Surgical treatment strategies, including management of the hip capsule, have evolved. Whereas earlier hip arthroscopies often involved capsulectomy or capsulotomy without repair, more recently capsular closure has been considered an important step in restoring the anatomy of the hip joint and preventing microinstability or gross macroinstability.

The anatomy of the hip joint includes both static and dynamic stabilizers designed to maintain a functioning articulation. The osseous articulation of the femoral head and acetabulum is the first static stabilizer, with variations in offset, version, and inclination of the acetabulum and the proximal femur. The joint capsule consists of 3 ligaments—iliofemoral, pubofemoral, and ischiofemoral—that converge to form the zona orbicularis. Other soft-tissue structures, such as the articular cartilage, the labrum, the transverse acetabular ligament, the pulvinar, and the ligamentum teres, also provide static constraint.¹ The surrounding musculature provides the hip joint with dynamic stability, which contributes to overall maintenance of proper joint kinematics.

Management of the hip capsule has evolved as our understanding of hip pathology and biomechanics has matured. Initial articles on using hip arthroscopy to treat labral tears described improvement in clinical outcomes,² but the cases involved limited focal capsulotomy. Not until the idea of femoroacetabular impingement (FAI) was introduced were extensive capsulotomies and capsulectomies performed to address the underlying osseous deformities and emulate open techniques. Soon after our ability to access osseous pathomorphology improved with enhanced visualization and comprehensive resection, cases of hip instability after hip arthroscopy surfaced.^3-5 Although frank dislocation after hip arthroscopy is rare and largely underreported, it is a catastrophic complication. In addition, focal capsular defects were also described in cases of failed hip arthroscopy and thought to lead to microinstability of the hip.⁶ Iatrogenic microinstability is thought to be more common, but it is also underrecognized as a cause of failure of hip arthroscopy.⁷Microinstability is a pathologic condition that can affect hip function. In cases of recurrent pain and unimproved functional status after surgery, microinstability should be considered. In an imaging study of capsule integrity, McCormick and colleagues⁶ found that 78% of patients who underwent revision arthroscopic surgery after hip arthroscopic surgery for FAI showed evidence of capsular and iliofemoral defects on magnetic resonance angiography. Frank and colleagues⁸ reported that, though all patients showed preoperative-to-postoperative improvement on outcome measures, those who underwent complete repair of their T-capsulotomy (vs repair of only its longitudinal portion) had superior outcomes, particularly increased sport-specific activity.

For patients undergoing hip arthroscopy, several predisposing factors can increase the risk of postoperative instability. Patient-related hip instability factors include generalized ligamentous laxity, supraphysiologic athletics (eg, dance), and borderline or true hip dysplasia. Surgeon-related factors include overaggressive acetabular rim resection, excessive labral débridement, and lack of capsular repair.^5,9 Although there are multiple techniques for accessing the hip joint and addressing capsular closure at the end of surgery,^9-14 we think capsular closure is an important aspect of the case.

Surgical Technique

For a demonstration of this technique, click here to see the video that accompanies this article. The patient is moved to a traction table and placed in the supine position. Induction of general anesthesia with muscle relaxation allows for atraumatic axial traction. The anesthetized patient is assessed for passive motion and ligamentous laxity. Well-padded boots are applied, and a well-padded perineal post is used for positioning. Gentle traction is applied to the contralateral limb, and axial traction is applied through the surgical limb with the hip abducted and minimally flexed. The leg is then adducted and neutrally extended, inducing a transverse vector cantilever moment to the proximal femur. The foot is internally rotated to optimize femoral neck length on an anteroposterior radiograph. The circulating nursing staff notes the onset of hip distraction in order to ensure safe traction duration.

Bony landmarks are marked with a sterile marking pen. Under fluoroscopic guidance, an anterolateral (AL) portal is established 1 cm proximal and 1 cm anterior to the AL tip of the greater trochanter. Standard cannulation allows for intra-articular visualization with a 70° arthroscope. A needle is used to localize placement of a modified anterior portal. After cannulation, the arthroscope is placed in the modified anterior portal to confirm safe entry of the portal without labral violation. An arthroscopic scalpel (Samurai Blade; Stryker Sports Medicine) is used to make a transverse interportal capsulotomy 8 mm to 10 mm from the labrum and extending from 12 to 2 o’clock; length is 2 cm to 4 cm, depending on the extent of the intra-articular injury (Figure 1A).

T-Capsulotomy

Pericapsular fatty tissue is débrided with an arthroscopic shaver to visualize the interval between the iliocapsularis and gluteus minimus muscles. An arthroscopic scalpel is used, through a 5.0-mm cannula in the DALA portal, to extend the capsulotomy longitudinally and perpendicular to the interportal capsulotomy (Figure 1C). The T-capsulotomy is performed along the length of the femoral neck distally to the capsular reflection at the intertrochanteric line. The arthroscopic burr is used to perform a femoral osteochondroplasty between the lateral synovial folds (12 o’clock) and the medial synovial folds (6 o’clock). Dynamic examination and fluoroscopic imaging confirm that the entire cam deformity has been excised and that there is no evidence of impingement.

Although various suture-shuttling or tissue-penetrating/retrieving devices may be used, we recommend whichever device is appropriate for closing the capsule in its entirety. With the arthroscope in the modified anterior portal, an 8.25-mm × 90-mm cannula is placed in the AL portal, and an 8.25-mm × 110-mm cannula in the DALA portal. These portals will facilitate suture passage.

The vertical limb of the T-capsulotomy is closed with 2 to 4 side-to-side sutures, and the interportal capsulotomy limb with 2 or 3 sutures. Capsular closure begins with the distal portion of the longitudinal limb at the base of the iliofemoral ligament (IFL). A crescent tissue penetrating device (Slingshot; Stryker Sports Medicine) is loaded with high-strength No. 2 suture (Zipline; Stryker Sports Medicine) and placed through the AL portal to sharply pierce the lateral leaflet of the IFL (Figure 1D). The No. 2 suture is shuttled into the intra-articular side of the capsule (Figure 1E). Through the DALA portal, the penetrating device is used to pierce the medial leaflet to retrieve the free suture (Figure 1F). Next, the looped suture retriever is used to pull the suture from the AL portal to the DALA portal so the suture can be tied. We prefer to tie each suture individually after it is passed, but all of the sutures can be passed first, and then tied. As successive suture placement and knot tying inherently tighten the capsule, successive visualization requires more precision. Each subsequent suture is similarly passed, about 1 cm proximal to the previous stitch.

After closure of the vertical limb of the T-capsulotomy, we prefer to close the interportal capsulotomy with the InJector II Capsule Restoration System (Stryker Sports Medicine), a device that allows for closure through a single cannula lateral to medial. This device is passed through the AL cannula in order to bring the suture end through the proximal IFL attached to the acetabulum (Figure 1G). The device is removed from the cannula, and the other suture end is placed in the device and passed through the distal IFL (Figure 1H). The stitch is then tensioned and tied. Likewise, closure of the medial IFL involves passing the InJector through the DALA cannula and bringing the first suture end through the proximal IFL attached to the acetabulum. The Injector is removed from the cannula, and the other suture end is placed in the device and passed through the distal IFL. The stitch is then tensioned and tied with the hip in neutral extension. Generally, 2 or 3 stitches are used to close the interportal capsulotomy. Complete capsular closure is confirmed by the inability to visualize the underlying femoral head/neck and by probing the anterior capsule to ensure proper tension (Figure 1I).

Extensile Interportal Capsulotomy

An alternative to T-capsulotomy is interportal capsulotomy. Just as with T-capsulotomy closure, multiple different suture passing devices can be used. Good visualization for accessing the peripheral compartment generally is achieved by making the interportal capsulotomy 4 cm to 6 cm longer than the horizontal limb of the T-capsulotomy (Figures 2A, 2B). Capsular closure usually begins with the medial portion of the interportal capsulotomy. With the arthroscope in the AL portal, the 8.25-mm × 90-mm cannula is placed in the midanterior portal (MAP), and an 8.25-mm × 110-mm cannula is placed in the DALA portal.

Ligamentous laxity determines degree of capsular closure. The capsular leaflets can be closed end to end if there is little concern for laxity and instability. If there is more concern for capsular laxity, a larger bite of the capsular tissue can be taken to allow for a greater degree of plication. Further, the interportal capsule can be tightened by alternately advancing the location where sutures are passed through the capsule. Specifically, the sutures are passed such that larger bites of the distal capsule are taken, increasing the tightness of the capsule in external rotation.⁹

Rehabilitation

After surgery, hip extension and external rotation are limited to decrease stress on the capsular closure. The patient is placed into a hip orthosis with 0° to 90° of flexion and a night abduction pillow to limit hip external rotation. Crutch-assisted gait with 20 lb of foot-flat weight-bearing is maintained the first 3 weeks. Continuous passive motion and use of a stationary bicycle are recommended for the first 3 weeks, and then the patient slowly progresses to muscle strengthening, including core and proximal motor control. Closed-chain exercises are begun 6 weeks after surgery. Treadmill running may start at 12 weeks, with the goal of returning to sport at 4 to 6 months.

Discussion

Capsular closure during hip arthroscopy restores the normal anatomy of the IFL and therefore restores the biomechanical characteristics of the hip joint. Scientific studies have found that capsular repair or plication after hip arthroscopy restores normal hip translation, rotation, and strain. Clinical studies have also demonstrated a lower revision rate and more rapid return to athletic activity. Capsular closure, however, is technically challenging and increases operative time, but gross instability and microinstability can be avoided with meticulous closure/plication.

Am J Orthop. 2017;46(1):49-54. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Hip capsule provides static stabilization for the hip joint.
• Capsular management must weigh visualization to address underlying osseous deformity but also repair/plication of the capsule to maintain biomechanical characteristics.
• T-capsulotomy provides optimal visualization with a small interportal incision with a vertical incision along the femoral neck.
• Extensile interportal capsulotomy is the most widely used capsulotomy and size may vary depending on capsular and patient characteristics.
• Orthopedic surgeons should be equipped to employ either technique depending on the patients individual hip pathomorphology.

Hip arthroscopy has emerged as a common surgical treatment for a number of hip pathologies. Surgical treatment strategies, including management of the hip capsule, have evolved. Whereas earlier hip arthroscopies often involved capsulectomy or capsulotomy without repair, more recently capsular closure has been considered an important step in restoring the anatomy of the hip joint and preventing microinstability or gross macroinstability.

The anatomy of the hip joint includes both static and dynamic stabilizers designed to maintain a functioning articulation. The osseous articulation of the femoral head and acetabulum is the first static stabilizer, with variations in offset, version, and inclination of the acetabulum and the proximal femur. The joint capsule consists of 3 ligaments—iliofemoral, pubofemoral, and ischiofemoral—that converge to form the zona orbicularis. Other soft-tissue structures, such as the articular cartilage, the labrum, the transverse acetabular ligament, the pulvinar, and the ligamentum teres, also provide static constraint.¹ The surrounding musculature provides the hip joint with dynamic stability, which contributes to overall maintenance of proper joint kinematics.

Management of the hip capsule has evolved as our understanding of hip pathology and biomechanics has matured. Initial articles on using hip arthroscopy to treat labral tears described improvement in clinical outcomes,² but the cases involved limited focal capsulotomy. Not until the idea of femoroacetabular impingement (FAI) was introduced were extensive capsulotomies and capsulectomies performed to address the underlying osseous deformities and emulate open techniques. Soon after our ability to access osseous pathomorphology improved with enhanced visualization and comprehensive resection, cases of hip instability after hip arthroscopy surfaced.^3-5 Although frank dislocation after hip arthroscopy is rare and largely underreported, it is a catastrophic complication. In addition, focal capsular defects were also described in cases of failed hip arthroscopy and thought to lead to microinstability of the hip.⁶ Iatrogenic microinstability is thought to be more common, but it is also underrecognized as a cause of failure of hip arthroscopy.⁷Microinstability is a pathologic condition that can affect hip function. In cases of recurrent pain and unimproved functional status after surgery, microinstability should be considered. In an imaging study of capsule integrity, McCormick and colleagues⁶ found that 78% of patients who underwent revision arthroscopic surgery after hip arthroscopic surgery for FAI showed evidence of capsular and iliofemoral defects on magnetic resonance angiography. Frank and colleagues⁸ reported that, though all patients showed preoperative-to-postoperative improvement on outcome measures, those who underwent complete repair of their T-capsulotomy (vs repair of only its longitudinal portion) had superior outcomes, particularly increased sport-specific activity.

For patients undergoing hip arthroscopy, several predisposing factors can increase the risk of postoperative instability. Patient-related hip instability factors include generalized ligamentous laxity, supraphysiologic athletics (eg, dance), and borderline or true hip dysplasia. Surgeon-related factors include overaggressive acetabular rim resection, excessive labral débridement, and lack of capsular repair.^5,9 Although there are multiple techniques for accessing the hip joint and addressing capsular closure at the end of surgery,^9-14 we think capsular closure is an important aspect of the case.

Surgical Technique

For a demonstration of this technique, click here to see the video that accompanies this article. The patient is moved to a traction table and placed in the supine position. Induction of general anesthesia with muscle relaxation allows for atraumatic axial traction. The anesthetized patient is assessed for passive motion and ligamentous laxity. Well-padded boots are applied, and a well-padded perineal post is used for positioning. Gentle traction is applied to the contralateral limb, and axial traction is applied through the surgical limb with the hip abducted and minimally flexed. The leg is then adducted and neutrally extended, inducing a transverse vector cantilever moment to the proximal femur. The foot is internally rotated to optimize femoral neck length on an anteroposterior radiograph. The circulating nursing staff notes the onset of hip distraction in order to ensure safe traction duration.

Bony landmarks are marked with a sterile marking pen. Under fluoroscopic guidance, an anterolateral (AL) portal is established 1 cm proximal and 1 cm anterior to the AL tip of the greater trochanter. Standard cannulation allows for intra-articular visualization with a 70° arthroscope. A needle is used to localize placement of a modified anterior portal. After cannulation, the arthroscope is placed in the modified anterior portal to confirm safe entry of the portal without labral violation. An arthroscopic scalpel (Samurai Blade; Stryker Sports Medicine) is used to make a transverse interportal capsulotomy 8 mm to 10 mm from the labrum and extending from 12 to 2 o’clock; length is 2 cm to 4 cm, depending on the extent of the intra-articular injury (Figure 1A).

T-Capsulotomy

Pericapsular fatty tissue is débrided with an arthroscopic shaver to visualize the interval between the iliocapsularis and gluteus minimus muscles. An arthroscopic scalpel is used, through a 5.0-mm cannula in the DALA portal, to extend the capsulotomy longitudinally and perpendicular to the interportal capsulotomy (Figure 1C). The T-capsulotomy is performed along the length of the femoral neck distally to the capsular reflection at the intertrochanteric line. The arthroscopic burr is used to perform a femoral osteochondroplasty between the lateral synovial folds (12 o’clock) and the medial synovial folds (6 o’clock). Dynamic examination and fluoroscopic imaging confirm that the entire cam deformity has been excised and that there is no evidence of impingement.

Although various suture-shuttling or tissue-penetrating/retrieving devices may be used, we recommend whichever device is appropriate for closing the capsule in its entirety. With the arthroscope in the modified anterior portal, an 8.25-mm × 90-mm cannula is placed in the AL portal, and an 8.25-mm × 110-mm cannula in the DALA portal. These portals will facilitate suture passage.

The vertical limb of the T-capsulotomy is closed with 2 to 4 side-to-side sutures, and the interportal capsulotomy limb with 2 or 3 sutures. Capsular closure begins with the distal portion of the longitudinal limb at the base of the iliofemoral ligament (IFL). A crescent tissue penetrating device (Slingshot; Stryker Sports Medicine) is loaded with high-strength No. 2 suture (Zipline; Stryker Sports Medicine) and placed through the AL portal to sharply pierce the lateral leaflet of the IFL (Figure 1D). The No. 2 suture is shuttled into the intra-articular side of the capsule (Figure 1E). Through the DALA portal, the penetrating device is used to pierce the medial leaflet to retrieve the free suture (Figure 1F). Next, the looped suture retriever is used to pull the suture from the AL portal to the DALA portal so the suture can be tied. We prefer to tie each suture individually after it is passed, but all of the sutures can be passed first, and then tied. As successive suture placement and knot tying inherently tighten the capsule, successive visualization requires more precision. Each subsequent suture is similarly passed, about 1 cm proximal to the previous stitch.

After closure of the vertical limb of the T-capsulotomy, we prefer to close the interportal capsulotomy with the InJector II Capsule Restoration System (Stryker Sports Medicine), a device that allows for closure through a single cannula lateral to medial. This device is passed through the AL cannula in order to bring the suture end through the proximal IFL attached to the acetabulum (Figure 1G). The device is removed from the cannula, and the other suture end is placed in the device and passed through the distal IFL (Figure 1H). The stitch is then tensioned and tied. Likewise, closure of the medial IFL involves passing the InJector through the DALA cannula and bringing the first suture end through the proximal IFL attached to the acetabulum. The Injector is removed from the cannula, and the other suture end is placed in the device and passed through the distal IFL. The stitch is then tensioned and tied with the hip in neutral extension. Generally, 2 or 3 stitches are used to close the interportal capsulotomy. Complete capsular closure is confirmed by the inability to visualize the underlying femoral head/neck and by probing the anterior capsule to ensure proper tension (Figure 1I).

Extensile Interportal Capsulotomy

An alternative to T-capsulotomy is interportal capsulotomy. Just as with T-capsulotomy closure, multiple different suture passing devices can be used. Good visualization for accessing the peripheral compartment generally is achieved by making the interportal capsulotomy 4 cm to 6 cm longer than the horizontal limb of the T-capsulotomy (Figures 2A, 2B). Capsular closure usually begins with the medial portion of the interportal capsulotomy. With the arthroscope in the AL portal, the 8.25-mm × 90-mm cannula is placed in the midanterior portal (MAP), and an 8.25-mm × 110-mm cannula is placed in the DALA portal.

Ligamentous laxity determines degree of capsular closure. The capsular leaflets can be closed end to end if there is little concern for laxity and instability. If there is more concern for capsular laxity, a larger bite of the capsular tissue can be taken to allow for a greater degree of plication. Further, the interportal capsule can be tightened by alternately advancing the location where sutures are passed through the capsule. Specifically, the sutures are passed such that larger bites of the distal capsule are taken, increasing the tightness of the capsule in external rotation.⁹

Rehabilitation

After surgery, hip extension and external rotation are limited to decrease stress on the capsular closure. The patient is placed into a hip orthosis with 0° to 90° of flexion and a night abduction pillow to limit hip external rotation. Crutch-assisted gait with 20 lb of foot-flat weight-bearing is maintained the first 3 weeks. Continuous passive motion and use of a stationary bicycle are recommended for the first 3 weeks, and then the patient slowly progresses to muscle strengthening, including core and proximal motor control. Closed-chain exercises are begun 6 weeks after surgery. Treadmill running may start at 12 weeks, with the goal of returning to sport at 4 to 6 months.

Discussion

Capsular closure during hip arthroscopy restores the normal anatomy of the IFL and therefore restores the biomechanical characteristics of the hip joint. Scientific studies have found that capsular repair or plication after hip arthroscopy restores normal hip translation, rotation, and strain. Clinical studies have also demonstrated a lower revision rate and more rapid return to athletic activity. Capsular closure, however, is technically challenging and increases operative time, but gross instability and microinstability can be avoided with meticulous closure/plication.

Am J Orthop. 2017;46(1):49-54. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Hip capsule provides static stabilization for the hip joint.
• Capsular management must weigh visualization to address underlying osseous deformity but also repair/plication of the capsule to maintain biomechanical characteristics.
• T-capsulotomy provides optimal visualization with a small interportal incision with a vertical incision along the femoral neck.
• Extensile interportal capsulotomy is the most widely used capsulotomy and size may vary depending on capsular and patient characteristics.
• Orthopedic surgeons should be equipped to employ either technique depending on the patients individual hip pathomorphology.

Hip arthroscopy has emerged as a common surgical treatment for a number of hip pathologies. Surgical treatment strategies, including management of the hip capsule, have evolved. Whereas earlier hip arthroscopies often involved capsulectomy or capsulotomy without repair, more recently capsular closure has been considered an important step in restoring the anatomy of the hip joint and preventing microinstability or gross macroinstability.

The anatomy of the hip joint includes both static and dynamic stabilizers designed to maintain a functioning articulation. The osseous articulation of the femoral head and acetabulum is the first static stabilizer, with variations in offset, version, and inclination of the acetabulum and the proximal femur. The joint capsule consists of 3 ligaments—iliofemoral, pubofemoral, and ischiofemoral—that converge to form the zona orbicularis. Other soft-tissue structures, such as the articular cartilage, the labrum, the transverse acetabular ligament, the pulvinar, and the ligamentum teres, also provide static constraint.¹ The surrounding musculature provides the hip joint with dynamic stability, which contributes to overall maintenance of proper joint kinematics.

Management of the hip capsule has evolved as our understanding of hip pathology and biomechanics has matured. Initial articles on using hip arthroscopy to treat labral tears described improvement in clinical outcomes,² but the cases involved limited focal capsulotomy. Not until the idea of femoroacetabular impingement (FAI) was introduced were extensive capsulotomies and capsulectomies performed to address the underlying osseous deformities and emulate open techniques. Soon after our ability to access osseous pathomorphology improved with enhanced visualization and comprehensive resection, cases of hip instability after hip arthroscopy surfaced.^3-5 Although frank dislocation after hip arthroscopy is rare and largely underreported, it is a catastrophic complication. In addition, focal capsular defects were also described in cases of failed hip arthroscopy and thought to lead to microinstability of the hip.⁶ Iatrogenic microinstability is thought to be more common, but it is also underrecognized as a cause of failure of hip arthroscopy.⁷Microinstability is a pathologic condition that can affect hip function. In cases of recurrent pain and unimproved functional status after surgery, microinstability should be considered. In an imaging study of capsule integrity, McCormick and colleagues⁶ found that 78% of patients who underwent revision arthroscopic surgery after hip arthroscopic surgery for FAI showed evidence of capsular and iliofemoral defects on magnetic resonance angiography. Frank and colleagues⁸ reported that, though all patients showed preoperative-to-postoperative improvement on outcome measures, those who underwent complete repair of their T-capsulotomy (vs repair of only its longitudinal portion) had superior outcomes, particularly increased sport-specific activity.

For patients undergoing hip arthroscopy, several predisposing factors can increase the risk of postoperative instability. Patient-related hip instability factors include generalized ligamentous laxity, supraphysiologic athletics (eg, dance), and borderline or true hip dysplasia. Surgeon-related factors include overaggressive acetabular rim resection, excessive labral débridement, and lack of capsular repair.^5,9 Although there are multiple techniques for accessing the hip joint and addressing capsular closure at the end of surgery,^9-14 we think capsular closure is an important aspect of the case.

Surgical Technique

For a demonstration of this technique, click here to see the video that accompanies this article. The patient is moved to a traction table and placed in the supine position. Induction of general anesthesia with muscle relaxation allows for atraumatic axial traction. The anesthetized patient is assessed for passive motion and ligamentous laxity. Well-padded boots are applied, and a well-padded perineal post is used for positioning. Gentle traction is applied to the contralateral limb, and axial traction is applied through the surgical limb with the hip abducted and minimally flexed. The leg is then adducted and neutrally extended, inducing a transverse vector cantilever moment to the proximal femur. The foot is internally rotated to optimize femoral neck length on an anteroposterior radiograph. The circulating nursing staff notes the onset of hip distraction in order to ensure safe traction duration.

Bony landmarks are marked with a sterile marking pen. Under fluoroscopic guidance, an anterolateral (AL) portal is established 1 cm proximal and 1 cm anterior to the AL tip of the greater trochanter. Standard cannulation allows for intra-articular visualization with a 70° arthroscope. A needle is used to localize placement of a modified anterior portal. After cannulation, the arthroscope is placed in the modified anterior portal to confirm safe entry of the portal without labral violation. An arthroscopic scalpel (Samurai Blade; Stryker Sports Medicine) is used to make a transverse interportal capsulotomy 8 mm to 10 mm from the labrum and extending from 12 to 2 o’clock; length is 2 cm to 4 cm, depending on the extent of the intra-articular injury (Figure 1A).

T-Capsulotomy

Pericapsular fatty tissue is débrided with an arthroscopic shaver to visualize the interval between the iliocapsularis and gluteus minimus muscles. An arthroscopic scalpel is used, through a 5.0-mm cannula in the DALA portal, to extend the capsulotomy longitudinally and perpendicular to the interportal capsulotomy (Figure 1C). The T-capsulotomy is performed along the length of the femoral neck distally to the capsular reflection at the intertrochanteric line. The arthroscopic burr is used to perform a femoral osteochondroplasty between the lateral synovial folds (12 o’clock) and the medial synovial folds (6 o’clock). Dynamic examination and fluoroscopic imaging confirm that the entire cam deformity has been excised and that there is no evidence of impingement.

Although various suture-shuttling or tissue-penetrating/retrieving devices may be used, we recommend whichever device is appropriate for closing the capsule in its entirety. With the arthroscope in the modified anterior portal, an 8.25-mm × 90-mm cannula is placed in the AL portal, and an 8.25-mm × 110-mm cannula in the DALA portal. These portals will facilitate suture passage.

The vertical limb of the T-capsulotomy is closed with 2 to 4 side-to-side sutures, and the interportal capsulotomy limb with 2 or 3 sutures. Capsular closure begins with the distal portion of the longitudinal limb at the base of the iliofemoral ligament (IFL). A crescent tissue penetrating device (Slingshot; Stryker Sports Medicine) is loaded with high-strength No. 2 suture (Zipline; Stryker Sports Medicine) and placed through the AL portal to sharply pierce the lateral leaflet of the IFL (Figure 1D). The No. 2 suture is shuttled into the intra-articular side of the capsule (Figure 1E). Through the DALA portal, the penetrating device is used to pierce the medial leaflet to retrieve the free suture (Figure 1F). Next, the looped suture retriever is used to pull the suture from the AL portal to the DALA portal so the suture can be tied. We prefer to tie each suture individually after it is passed, but all of the sutures can be passed first, and then tied. As successive suture placement and knot tying inherently tighten the capsule, successive visualization requires more precision. Each subsequent suture is similarly passed, about 1 cm proximal to the previous stitch.

After closure of the vertical limb of the T-capsulotomy, we prefer to close the interportal capsulotomy with the InJector II Capsule Restoration System (Stryker Sports Medicine), a device that allows for closure through a single cannula lateral to medial. This device is passed through the AL cannula in order to bring the suture end through the proximal IFL attached to the acetabulum (Figure 1G). The device is removed from the cannula, and the other suture end is placed in the device and passed through the distal IFL (Figure 1H). The stitch is then tensioned and tied. Likewise, closure of the medial IFL involves passing the InJector through the DALA cannula and bringing the first suture end through the proximal IFL attached to the acetabulum. The Injector is removed from the cannula, and the other suture end is placed in the device and passed through the distal IFL. The stitch is then tensioned and tied with the hip in neutral extension. Generally, 2 or 3 stitches are used to close the interportal capsulotomy. Complete capsular closure is confirmed by the inability to visualize the underlying femoral head/neck and by probing the anterior capsule to ensure proper tension (Figure 1I).

Extensile Interportal Capsulotomy

An alternative to T-capsulotomy is interportal capsulotomy. Just as with T-capsulotomy closure, multiple different suture passing devices can be used. Good visualization for accessing the peripheral compartment generally is achieved by making the interportal capsulotomy 4 cm to 6 cm longer than the horizontal limb of the T-capsulotomy (Figures 2A, 2B). Capsular closure usually begins with the medial portion of the interportal capsulotomy. With the arthroscope in the AL portal, the 8.25-mm × 90-mm cannula is placed in the midanterior portal (MAP), and an 8.25-mm × 110-mm cannula is placed in the DALA portal.

Ligamentous laxity determines degree of capsular closure. The capsular leaflets can be closed end to end if there is little concern for laxity and instability. If there is more concern for capsular laxity, a larger bite of the capsular tissue can be taken to allow for a greater degree of plication. Further, the interportal capsule can be tightened by alternately advancing the location where sutures are passed through the capsule. Specifically, the sutures are passed such that larger bites of the distal capsule are taken, increasing the tightness of the capsule in external rotation.⁹

Rehabilitation

After surgery, hip extension and external rotation are limited to decrease stress on the capsular closure. The patient is placed into a hip orthosis with 0° to 90° of flexion and a night abduction pillow to limit hip external rotation. Crutch-assisted gait with 20 lb of foot-flat weight-bearing is maintained the first 3 weeks. Continuous passive motion and use of a stationary bicycle are recommended for the first 3 weeks, and then the patient slowly progresses to muscle strengthening, including core and proximal motor control. Closed-chain exercises are begun 6 weeks after surgery. Treadmill running may start at 12 weeks, with the goal of returning to sport at 4 to 6 months.

Discussion

Capsular closure during hip arthroscopy restores the normal anatomy of the IFL and therefore restores the biomechanical characteristics of the hip joint. Scientific studies have found that capsular repair or plication after hip arthroscopy restores normal hip translation, rotation, and strain. Clinical studies have also demonstrated a lower revision rate and more rapid return to athletic activity. Capsular closure, however, is technically challenging and increases operative time, but gross instability and microinstability can be avoided with meticulous closure/plication.

Am J Orthop. 2017;46(1):49-54. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.