PROGNOSTICATION OF NONTRAUMATIC AVASCULAR NECROSIS OF THE FEMORAL-HEAD - SIGNIFICANCE OF LOCATION AND SIZE OF THE NECROTIC LESION

After reviewing the radiographs of 149 hips ,vith nontraumatic avascul ar necrosis of the femoral head (ANFH), a method for evaluating the pr ognosis in patients with ANFH in its early stages was devised. The eva luation was made primarily by classifying the radiographic features of each involved femoral head according to the location and size of its necrotic lesion. In a group of 120 hips, massive collapse occurred wit hout exception in cases where both of the following criteria were true . First, in a standing position, the necrotic lesion involved more tha n the medial one third of the weight-bearing surface from the anteropo sterior view. Second, from the lateral view, the lesion occupied more than 43% of the total area of the femoral head. However, in 29 hips, t he extent and size of necrosis was less than the above, and no massive collapse occurred during the follow-up period of three to 15 years (a verage, 5.2 years). In these 29 hips, function was preserved. These da ta suggest that hips with a high risk for collapse can be reliably sel ected during the early stages of ANFH.