Hip joint dislocations usually occur in high-velocity traumas. In a nonpathological hip, the recurrence of dislocations in the absence of an osseous defect is rare.~( 4 , 5 , 7 )Low-velocity mechanisms have been described and recently associated with cam-type femoroacetabular impingement (FAI). FAI involves an abnormal contact between the femur and the acetabulum. Cam-type FAI implies a loss of the normal osseous concavity at the femoral head and neck junction, while pincer-type FAI reveals an excessive femoral head cover by the acetabulum.~( 12 )This report discusses a recurrent dislocation of the hip presenting a cam-type FAI and a Bankart-like posterior capsular lesion. Case Report A healthy 16-year-old female experienced her first hip dislocation after an alpine ski fall. A closed reduction was performed in the emergency department. Conservative treatment was initiated, with a nonweightbearing period of 2 weeks followed by a progressive return to normal activities. Follow-up was discontinued because she was not experiencing any residual pain or instability. Five years later, at the age of 21, she was quarreling with a friend when she sustained an atraumatic posterior hip dislocation resulting from an unclear mechanism of traction and torsion on her previously injured leg. Her neurovascular examination was normal, and radiographs revealed a posterior hip dislocation with no signs of fracture ( Figure 1 ). Within 2 hours of the injury, a closed reduction using the Allis maneuver was performed in the emergency department with the patient under sedation.~( 7 ) Figure 1. Second episode of right hip posterior dislocation. A postreduction computed tomography (CT) scan showed a concentric hip with a small nondisplaced subchondral fracture (<1 cm) around the footprint of the round ligament ( Figure 2 ). Conservative treatment was initiated, with a nonweightbearing period of 4 weeks and progressive rehabilitation. Figure 2. Computed tomography scan of a concentric right hip after closed reduction showing no posterior wall fracture. The patient was referred to us at 6 weeks postinjury complaining of instability during pivoting in sports and occasional pain. Physical examination revealed an asymmetric increased external rotation (70° with the hip flexed to 90°) and a unilateral excessive pistoning of the injured hip with an axial telescoping test of the hip in extension and neutral rotation. A posterior subluxation was reproduced by internal rotation of the leg in more than 30° of flexion. A 5-week trial of strengthening exercises in physical therapy did not improve her symptoms. A magnetic resonance arthrogram (MRA) at 5 months from the trauma showed a large posterior capsular tear and a cam-type morphology with an alpha angle of 58° ( Figure 3 ). The acetabular index and the lateral center-edge angle were normal, with angles of 8.7° and 31.2°, respectively. An anterosuperior labral tear was also suspected. A 2-step surgical management was offered to address, in the same surgical setting, both the posterior capsular avulsion and the cam-type FAI. Figure 3. (A) Magnetic resonance arthrogram of the right hip showing the posterior contrast extrusion and absent posterior capsule. (B) Cam-type femoroacetabular impingement with an alpha angle of 58° on the sagittal oblique view. First, an osteoplasty of the femoral neck was performed by an anterior Smith-Petersen mini-approach.~( 6 )The patient was supine with a 45° wedge under her right buttock. An anterior capsulotomy was performed and revealed engagement of the anterolateral portion of the femoral neck on the acetabulum in 80° of hip flexion causing a lever action on the femoral head, and this phenomenon occurred earlier in hip flexion with some internal rotation. The prominent osseous anterolateral femoral neck was removed with a 6.5-mm bur. No labral tear was observed when the femoral head was subluxated by applying axial traction to the leg.Second, the patient was placed in the lateral decubitus position, and a limited K?cher-Langenbeck approach was performed. The short external rotators were found to be torn midsubstance, but the quadratus femoris muscle was intact. A large tear of the posteroinferior capsule was present. The quadratus femoris was reflected from the ischium to visualize adequately the ischial bone. Two double-loaded bone anchors with No. 2 nonabsorbable sutures (TwinLoop FLEX 3.5 mm; Stryker) were fixed to the ischial bone just posterior to the intact labrum in the inferior third of the posterior acetabular facet. A capsular repair was performed by use of horizontal mattress sutures to the residual capsule parallel with the fibers of the external obturator. The external rotators were then repaired with simple sutures (Polysorb 1; Medtronic). An intraoperative assessment showed improved stability, with a decrease in internal rotation and adduction in the hip flexed from 50° to 90°.Postoperatively, partial weightbearing was immediately authorized
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