NATURAL-HISTORY AND TREATMENT OF INSTABILITY OF THE HIP IN PROXIMAL FEMORAL FOCAL DEFICIENCY

We studied 67 patients with 78 affected femurs to determine the natura l history of proximal femoral focal deficiency (PFFD) with respect to hip instability and to establish guidelines for management. Using the classification systems of Aitken and Fixsen and Lloyd-Roberts as appli ed to a radiogragh taken at age 12-15 months, we could accurately pred ict development of hip instability, defined as formation of a pseudoar throsis or complete failure of hip development. The pseudoarthrosis oc curred either at the cervical or subtrochanteric level of the femur. C ervical instability was difficult to treat operatively, but subtrochan teric instability fused spontaneously in 30% of cases and responded we ll to operative treatment when necessary. For unilateral failure of hi p joint formation, various surgical procedures were used to assist pro sthetic fitting, but bilateral cases were treated nonoperatively.