Epidemiology, Cause, and Anatomy of Osteonecrosis of the Foot and Ankle.

Osteonecrosis arises throughout the foot and ankle in various forms and due to numerous causes, with a thousand US cases per year estimated for the ankle alone. Although research continues to elucidate specific mechanisms at work, the pathophysiology remains poorly understood. Nevertheless, the various osteonecrosis pathways converge on osteocyte death, and bony lesions follow a pattern of progression. Understanding the specific anatomy and biomechanics associated with common forms of foot and ankle osteonecrosis should help guide diagnosis and interventions, particularly at earlier stages of disease where etiology-specific approaches might become optimal.