Recurrent posterior dislocation of the hip with a bankart-type lesion: a case report.

causing him to fall awkwardly to the ground. He was unable to bear weight. He was transported to a nearby hospital emergency department, where he was noted to be in considerable pain, with his leg foreshortened, adducted, and internally rotated. Anteroposterior and lateral radiographs demonstrated a posterior dislocation of the left hip. Within 2 hours of the injury, gentle traction and manipulation under intravenous sedation resulted in reduction. The hip was stable throughout the range of motion, although no effort was made to posteriorly translate the femoral head. Plain films and computed tomography scan after manipulation showed concentric reduction, minimal injury to the posterior acetabulum, and only small bony extra-articular fragments. The patient was placed in Buck traction for 2 weeks, followed by progressive weightbearing until he was fully ambulatory at 6 weeks after injury. At 12 weeks, physical examination showed a full and painless range of motion, normal strength at manual testing, and no apprehension on axial or posterior translation testing. Anteroposterior and lateral radiographs, as well as MRI, showed normal findings, with the exception of a small intra-articular effusion. He was permitted to gradually return to athletic activities starting at 14 weeks after injury, as he was anticipating returning to high school lacrosse as a goalie. Two weeks subsequent to his clearance, at 16 weeks after his initial injury, he sustained a recurrent injury while playing lacrosse in goal. When coming down from a jump, he landed awkwardly on his left leg and experienced acute pain and a recurrent posterior dislocation of his left hip. He underwent prompt closed reduction under intravenous sedation in the emergency department. While under this sedation, the hip was unstable in 90° of flexion with only slight internal rotation with a posterior-directed force. Postreduction radiographs revealed a concentric reduction with no significant bony injury. Postreduction MRI demonstrated detachment and displacement of the posterior capsule of the hip from the acetabular rim (Figure 1). Recurrent dislocation of the hip joint is a rare complication of posterior hip dislocation. Most often, recurrent dislocation of the hip is associated with fractures of significant portions of the posterior wall of the acetabulum. Some authors have attempted to correlate the size of acetabular fracture and condition of posterior capsule with stability of the hip. The contribution of soft tissue structures to hip stability has not been considered clinically significant, and thus has been given little attention. Although tearing of the acetabular labrum after hip dislocation has been described, its affect on hip stability has yet to be clearly defined. However, there is some evidence suggesting that the labrum contributes significantly to hip joint stability. Surgical repair of a “Bankart-type” avulsion of the posterior hip capsule from the posterior acetabular rim is an even less common occurrence. The purpose of this case report is to describe a patient with recurrent posterior instability of the hip who was treated with an open posterior Bankart repair of the hip.