Avascular necrosis (AVN) of the femoral head is a progressive disease that predominantly affects younger patients. The disease is characterized by a vascular insult to the femoral head blood supply, which can lead to collapse of the femoral head and subsequent degenerative changes. The exact pathophysiology underlying AVN has yet to be elucidated, although a number of risk factors have been determined. The diagnosis of AVN is commonly made based on clinical and radiological findings. Radiographs are initially performed; however, MRI has become the gold standard for diagnosis and has proven beneficial in staging patients. Most surgeons attempt to diagnose and treat AVN in the early stages, prior to collapse of the femoral head. There are a number of nonoperative and operative treatments that have been investigated for early stage AVN. Nonoperative modalities include statins, stanozolol, and bisphosphonates. Operative treatments include core decompression alone, core decompression with injection of bone marrow aspirate, or placement of some form of bone substitute and osteotomies. Nonsurgical options are ineffective after femoral head collapse, and treatment options become more invasive. Bone-preserving techniques utilized for post-collapse AVN include vascularized fibula grafts and osteotomies, but their results are unpredictable.
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