Avascular Necrosis Secondary to Traumatic Posterior Hip Dislocation.

BACKGROUND: Avascular necrosis of the femoral head, a known long-term complication following traumatic posterior hip dislocation, can result in femoral head collapse, osteochondral defects, and eventual posttraumatic osteoarthritis. This condition is especially problematic in young, active patients for whom total hip arthroplasty survivorship is a concern. Biologic treatments are therefore preferable to delay or avoid total hip arthroplasty. CASE REPORT: A 16-year-old male developed progressive left hip pain after a posterior dislocation sustained while playing football. The hip was emergently reduced. Imaging (x-ray, computed tomography, and magnetic resonance imaging [MRI]) showed a small depressed cortical fracture on the anterior and superior femoral head. Conservative treatment included protected weight-bearing for 6 weeks, knee immobilization to restrict hip flexion, physical therapy, and a home exercise program. However, symptoms worsened after 5 months of conservative care. Repeat MRI demonstrated avascular necrosis with associated cartilage loss, hip effusion, and femoroacetabular impingement (a cam deformity). Given the patient's young age, persistent symptoms, functional limitations, and radiographic findings, the decision was made to perform surgical intervention. Surgical hip dislocation via an anterolateral approach with a small trochanteric osteotomy (modified Hardinge approach) was used to expose the femoral head while maintaining the remaining blood supply. Fresh femoral head osteochondral allograft transplantation was performed, along with femoral neck osteoplasty to address the cam deformity. CONCLUSION: Osteochondral allograft transplantation is an effective technique to treat osteochondral defects of the femoral head in the setting of avascular necrosis following traumatic hip dislocation. This surgical option restores hip function and may delay or prevent total hip arthroplasty in young, active patients.