Postarthroscopic osteonecrosis of the knee.

Little is known about the etiology of postarthroscopic osteonecrosis of the knee. Its prevalence is probably very low. The most important differential diagnosis is pre-existing and undiagnosed early-stage spontaneous osteonecrosis of the knee. From the medicolegal point of view, orthopaedic surgeons need to be aware of the diagnostic pitfalls in differentiating between postarthroscopic osteonecrosis of the knee and spontaneous osteonecrosis of the knee, and they must understand that both may be unpreventable conditions. The purpose of this report is to review the presumable pathophysiology and the clinical and radiographic features as well as the pitfalls in diagnosing postarthroscopic osteonecrosis of the knee.