TOTAL HIP-ARTHROPLASTY FOR CONGENITAL DYSPLASIA OR DISLOCATION OF THEHIP - SURVIVORSHIP ANALYSIS AND LONG-TERM RESULTS

Two hundred and thirty-two total hip replacements with cement were per formed between 1965 and 1987 in 190 patients who had osteoarthrosis se condary to acetabular dysplasia resulting from congenital dysplasia or dislocation of the hip. Forty-nine patients (fifty hips) who died or who did not have at least three years of clinical and radiographic fol low-up were excluded; therefore, the study comprised 141 patients (182 hips), 125 of whom were women and sixteen of whom were men. The mean age at the time of the operation was 42.5 years (range, 19.5 to 76.5 y ears), and the mean duration of follow-up was 9.9 years (range, 3.1 to 22.8 years). A Charnley low-friction prosthesis with a 22.25-millimet er femoral head was used in all hips. A trochanteric osteotomy was per formed in 164 hips. A direct lateral approach was used only when there was a limb-length discrepancy of less than two centimeters. Bulk auto genous graft was not used to augment the fixation of the acetabular co mponent. The hips were divided into two groups on the basis of the deg ree of subluxation or dislocation according to the classification of C rowe et al. One hundred and thirty-six hips were grade I, II, or III ( indicating subluxation) (Group S), and forty-six hips were grade IV (i ndicating dislocation) (Group D). At the most recent follow-up evaluat ion, 128 (94 per cent) of the 136 hips in Group S and forty-four (96 p er cent) of the forty-six hips in Group D caused no or only slight pai n (a score of 6 or 5 points, respectively, according to the system of Merle d'Aubigne and Postel). Nineteen cups (10 per cent) and five stem s (3 per cent) failed and were revised. The rate of revision for loose ning of the femoral component in Group D (2 per cent [one stem]) was s imilar to that in Group S (3 per cent [four stems]). In comparison, th e rate of revision of the acetabular component in Group D (15 per cent [seven cups]) was almost twice that in Group S (9 per cent [twelve cu ps]). This study demonstrated satisfactory clinical results at a mean of nearly ten years. The fixation of the femoral components appeared t o be satisfactory; however, the failure of the fixation of the acetabu lar components in Group D (the dislocated hips) is a cause for concern .