SURVIVAL OF HIP SHELF ARTHROPLASTY IN ADU LTS AT A MINIMUM FOLLOW-UP PERIOD OF 15 YEARS - LATE RESULTS AND REASONS FOR FAILURE IN 56 DYSPLASTIC HIPS

Purpose of the study The goal of this study was to evaluate late resul ts of hip shelf arthroplasty in adults after a minimum of 15 years fol low-up. Material 65 hip shelf arthroplasty performed for painful hip d ysplasia between 1964 and 1977 were studied retrospectively in 1992. T hese 65 procedures were performed in 57 patients mean aged 32 +/- 14 y ears [17-56]. Nine patients (9 hips) were excluded (2 deceaded, 5 lost for follow-up, and two reoperated because of severe infection), Conse quently, the functional results were evaluated for 56 hips (48 patient s). Before surgery, according to Merle d'Aubigne's hip rating system, all the hips were painfull (mean pain score was 2,6 +/- 1,7 [0-5]). On radiography, all the hips had a dysplastic acetabulum and arthritic c hanges. Arthritic changes were severe in 32 hips (57.1 per cent). Meth ods The hip shelf arthroplasty was carried out according to Roy-Camill e. 10 hips had additional varus femoral osteotomy. The 48 patients (56 hips) included were evaluated by means of Merle d'Aubigne's hip ratin g system and AP and false lateral weight-bearing Xrays. In 1992, 24 pr ocedures were changed for total hip replacement (THR) (17 before 15 ye ars (early failure) and 7 after 15 yeas of follow-up (late failure)). These 24 hips were included with their last hip rating observed just b efore THR. Survival analysis was performed according to Kaplan-Meier u sing date of revision for THR as end-point. Results After 16.1 +/- 5.6 years of follow-up the functional score for 56 hips was : excellent i n 4 hips, very good in 7 hips, good in 10, satisfactory in 14, poor in 17, and bad in 4. The survival rate established for 65 hips was 60 pe r cent at 15 years and 40 per cent at 21 years. Only 39 hips shelf art hroplasties were still functional after 15 years (mean follow-up 19.1 +/- 3 years [16-28], but 18 hips (46.1 per cent) were painfree or slig htly painful (pain score to 5 or 6). Among these 39 hips, the results were excellent in 4 hips, very good in 7 hips, good in 10, satisfactor y in 10, poor in 6, and bad in 2. Arthritic change was the main reason for failures : the Kaplan-Meier survival rate at 21 years was 87 per cent when arthrosis was slight and only 15 per cent and 42 per cent wh en arthrosis was moderate to severa (p = 0.0001). The adverse effect o f arthrosis was promoted by lack of congruency for early failures, and by severity of dysplasia and hip subluxation for late failures, The a dditional femoral varus osteotomies had no influence on functional or radiographic outcome. Discussion Our study indicated that hip shelf ar throplasty performed for painfull acetabular dysplasia in adult has a 40 per cent probability survival rate at 21 years. The high rate of re vision (42.8 per cent) could be related to the prevalence of severe pr e-operative arthrosis. The low rate of lost for follow-up (8,7 per cen t) and the long follow-up period (16,1 years) made our conclusion reli able. Conclusion In spite of a high revision rate we recommend shelf a throplasty to treat acetabular dysplasia in adults, This procedure, ve ry reliable in cases of moderate arthrosis, could be performed in case s of severe arthrosis to delay and make easier THR, but a low survival rate could be expected unless dysplasia, lack of congruency and sublu xation were mild.