RESULTS OF TOTAL HIP-ARTHROPLASTY FOR CROWE TYPE-III DEVELOPMENTAL HIP-DYSPLASIA

From 1969 through 1980, 90 hips in 82 patients had cemented total hip arthroplasty for Type III developmental hip dysplasia, Seventy hips we re reviewed at an average of 16.6 Sears (range, 5-23 years) after oper ation, Aseptic loosening developed in 53% of acetabular cups and 40% o f femoral stems, Despite attempts to place acetabular components in th e anatomic center, 18 cups (25.7%) were placed outside that area, Usin g a measurement method to determine the true acetabular region and app roximate femoral head center, final acetabular loosening strongly corr elated with initial cup placement, Loosening occurred in 15 of 18 cups (83.3 %) initially positioned outside of the true acetabular region c ompared with loosening in 22 of 52 cups (42.3 %) initially positioned within the true acetabular region, Acetabular loosening also correlate d with initial lateral displacement or initial superior displacement o f the hip center from the approximate femoral head center. Initial cup placement medial to the approximate femoral head center was predictiv e of successful long term acetabular component fixation. The method of acetabular reconstruction did not affect eventual cup loosening. Plac ement of the hip arthroplasty center of rotation in or near the true a cetabular region is recommended.