EFFECT OF THE ELEVATED-RIM ACETABULAR LINER ON LOOSENING AFTER TOTAL HIP-ARTHROPLASTY

Citation
Tk. Cobb et al., EFFECT OF THE ELEVATED-RIM ACETABULAR LINER ON LOOSENING AFTER TOTAL HIP-ARTHROPLASTY, Journal of bone and joint surgery. American volume, 79A(9), 1997, pp. 1361-1364
Citations number
13
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Orthopedics,Surgery
ISSN journal
0021-9355
Volume
79A
Issue
9
Year of publication
1997
Pages
1361 - 1364
Database
ISI
SICI code
0021-9355(1997)79A:9<1361:EOTEAL>2.0.ZU;2-D
Abstract
Elevated-rim acetabular liners recently were shown to be associated wi th improved stability of total hip prostheses in a large clinical seri es. However, the effect of this design on loosening remains unknown. T o address this question, we reviewed the results of 5167 primary and r evision total hip arthroplasties that had been performed at our instit ution from September 1, 1985, through December 31, 1991; 2469 of the a cetabular components hail an elevated-rim liner (10 degrees of elevati on), and 2698 had a standard liner. Five-year follow-up data were avai lable for 1237 hips (174 that had an elevated-rim acetabular liner and 1063 that had a standard acetabular liner). The cumulative probabilit y of revision because of loosening of the implant was estimated as a f unction of time since the operation with use of the Kaplan-Meier survi vorship method. The five-year probability of survival of the acetabula r component was 98.8 per cent (95 per cent confidence interval, 97.9 t o 99.6 per cent) for the prostheses that had an elevated-rim liner and 98.3 per cent (95 per cent confidence interval, 97.7 to 99.0 per cent ) for those that had a standard liner (p = 0.87). The effect of the el evated-rim acetabular liner on the probability of revision because of loosening of the acetabular or the femoral component was analyzed for several subgroups: components inserted with cement, components inserte d without cement, primary total hip arthroplasties, revision total hip arthroplasties, male patients, and female patients. With the numbers available, no significant differences were found in the probability of survival of the acetabular or the femoral component in any of the sub groups. Theoretical considerations suggest that the geometric design o f the elevated-rim acetabular liner may have biomechanical characteris tics that predispose the implant to early loosening. However, our init ial review of the results of total hip arthroplasties after a mean fol low-up period of five years (range, 0.25 to tell years) failed to demo nstrate any difference in the cumulative probability of revision becau se of loosening of the implant. Continued surveillance is warranted an d ongoing.