Avascular Necrosis of the Hip

Osteonecrosis of the femoral head (ONFH) is a relatively common and challenging disorder affecting predominantly young patient population (<50 years; average age of 36 years). Higher risk of ONFH is evident among patients with certain predisposing risk factors (e.g., alcohol abuse, corticosteroid use, hypercoagulable states, hematological disorders, immunosuppression, irradiation, chemotherapy, storage disease, genetic conditions, and multiple medical comorbidities). Various insults lead to a final common pathway of interruption of femoral head blood supply, subchondral necrosis, collapse, loss of articular congruency, joint destruction, and secondary osteoarthritis. Indeed, if untreated, 70–80% of patients may progress to irreversible end-stage joint destruction. As such, early diagnosis and stage-appropriate management are critical to mitigate disease progression. Early intervention (pre-collapse stage of the femoral head) allows for a variety of therapeutic options, including non-operative treatment as well as joint-preserving core decompression and bone grafting. Conversely, necrotic expanding lesions relative to femoral head volume and those with head collapse become (>2 mm) necessitate total hip arthroplasty.