Preliminary traction and the use of under-thigh pillows to prevent avascular necrosis of the femoral head in Pavlik harness treatment of developmental dysplasia of the hip.

One hundred and sixty-one hips of 145 patients were treated with the Pavlik harness for developmental dysplasia of the hip. The patients were divided into two groups. Group A consisted of 65 patients (70 hips) who were treated between 1980 and 1987. The harness was applied immediately after the diagnosis. Group B consisted of 80 patients (91 hips) who were treated between 1988 and 1992. These patients received preliminary traction, and small pillows supported the lower extremities from just above the knee to the foot to prevent extreme abduction when the harness was applied. When the distance from the middle point of the proximal metaphyseal border of the femur to the Y-line (distance "a") was 8 mm or more on the initial X-ray picture, the rate of avascular necrosis in group A was 11% and that in group B was 0%; the difference was significant. However, when distance "a" was less than 8 mm, the rate of avascular necrosis in group A was 13% and that in group B was 12%, and there was no significant difference. Thus, we suggest that the Pavlik harness is indicated for developmental dysplasia of the hip in which distance "a" is 8 mm or more. Traction should precede application of the harness, and pillows placed under the thigh must be used during application.