AVASCULAR NECROSIS IN PATIENTS TREATED WITH THE PAVLIK HARNESS FOR CONGENITAL DISLOCATION OF THE HIP

Two hundred and seveny hips of 220 patients were treated with the Pavlik harness for congenital dislocation. Two hundred and thirty-three hips were dislocated, and thirty-seven hips had acetabular dysplasia. Of the 233 dislocated hips, thirteen (6 per cent) were not reduced. In one hundred and eighty-four hips that were successfully reduced, avascular necrosis did not develop. Avascular necrosis was observed in thirty-six (16 per cent) of the 220 reduced hips. Of these, twenty-seven hips were followed for five to twenty years (average, nine years). The result was excellent or good in eighteen hips (67 per cent), fair in three (11 per cent), and a failure in six (22 per cent). Avascular necrosis was seen in one of the thirty-seven hips that had acetabular dysplasia, and it was found even in the normal hip of a patient who had unilateral dislocation. In this study, the amount of displacement was represented by distances a and b, as defined by Yamamuro and Chene. Distance a is the length from the middle point of the proximal metaphyseal border of the femur to the Y-line, and distance b is the distance from the same point to the lateral margin of the ischium. When distance a was more than four millimeters, the over-all rate of reduction was 97 per cent (209 of 215 hips), ranging from 96 per cen (eighty-two of eighty-five hips) when distance a was eight to ten millimeters to 100 per cent (twenty-nine hips) when distance a was more than ten millimeters. However, when distance a was less than four millimeters, the rate of reduction decreased to 61 per cent (eleven of eighteen hips). The incidence of avascular necrosis rose as distance a decreased; it was 13 per cent (eleven of eighty-two reduced hips) when a was eight to ten millimeters, 17 per cent (twelve of seventy reduced hips) when a was six to eight millimeters, 21 per cent (six of twenty-eight reduced hips) when a was four to six millimeters, and 27 per cent (three of eleven reduced hips) when a was less than four millimeters. Thus, the more severe the dislocation, the higher the rates of both failed reduction and avascular necrosis as a complication of treatment with the Pavlik harness.