Traumatic posterior hip subluxation in American football

Background: Traumatic posterior hip subluxation is a potentially devastating injury that is often misdiagnosed as a simple hip sprain or strain. The purpose of the present study was to outline the injury mechanism, pathoanatomy, clinical and radiographic findings, and treatment of traumatic hip subluxation in an athletic population. Methods: Over a nine-year period, eight participants in American football who had sustained a traumatic posterior hip subluxation were evaluated and treated. The injury mechanism, clinical findings, and radiographic findings were reviewed. The mean duration of follow-up was thirty-four months. Results: The most common mechanism of injury was a fall on a flexed, adducted hip. Physical examination revealed painful limitation of hip motion. Initial radiographs demonstrated a characteristic posterior acetabular lip fracture. Initial magnetic resonance images revealed disruption of the iliofemoral ligament, hemarthrosis, and a viable femoral head. Two players were treated acutely with hip aspiration, and all eight players were treated with a six-week regimen of toe-touch weight-bearing with use of crutches. Six players recovered and returned to the previous level of competition. Two players had development of severe osteonecrosis and ultimately required total hip arthroplasty. Conclusion: The pathognomonic radiographic and magnetic resonance imaging triad of posterior acetabular lip fracture, iliofemoral ligament disruption, and hemarthrosis defines traumatic posterior hip subluxation. Patients in whom large hemarthroses are diagnosed on magnetic resonance images should undergo acute aspiration, and all players should be treated with a six-week regimen of toe-touch weight-bearing with use of crutches. Patients who have no sign of osteonecrosis on magnetic resonance imaging at six weeks can safely return to sports activity. Patients in whom osteonecrosis is diagnosed at six weeks are at risk for collapse and joint degeneration, and they should be advised against returning to sports. Level of Evidence: Prognostic study, Level IV (case series). See Instructions to Authors for a complete description of levels of evidence.