Natural history of avascular necrosis in the talus: when to operate.

Avascular necrosis (AVN) of the talus bone is a progressive and debilitating consequence of trauma or exposure to a variety of risk factors. The Ficat classification describes current understanding of the natural history of AVN, including preclinical, preradiographic, precollapse, postcollapse, and arthritic stages.

The size and location of the avascular region likely determines risk of progression; however, symptoms do not correlate with stage. Patients may be minimally symptomatic despite diffuse involvement for long periods.

Joint-sparing strategies have shown promise but do not universally prevent progression of the disease. When bone structure fails, joint-sacrificing strategies may be required.