Medium-term result of Elite Plus hip arthroplasty: the second modular evolution of the original Charnley low-friction arthroplasty

BackgroundThe Elite Plus total hip arthroplasty (THA) system was introduced as the second modular evolution of the original Charnley low-friction arthroplasty. However, the results of the Elite Plus THA are currently considered to be inconsistent. The aim of this study was to clarify the medium-term results and the factors affecting the results of Elite Plus THA.MethodsThe results of 97 Elite Plus THAs in 87 patients at 5 years or more postoperatively were reviewed. The patients’ mean age was 65 years, and follow-up averaged 8.0 years. The Elite Plus stem was used in all hips, and three designs of socket, Hylamer Ogee in 40 hips, Wroblewski Offset Bore in 38, and Charnley Ogee in 19, were implanted. The survival rates with loosening and revision as endpoints were analyzed. To clarify the risk factors affecting the survival rates, Charnley’s functional classification, Bombelli’s classification, Crowe’s classification, structural bone grafting of the acetabulum, cup design, stem position, and grading of the cement mantle were evaluated.ResultsThe stem survival rate with aseptic loosening as the endpoint was 96 %, and the rate with revision was 100 %. The cup survival rate with aseptic loosening as the endpoint was 80 %, and the rate with revision was 93 %. Using a Cox proportional hazards model, cup design was a potential confounding factor for acetabular loosening (p = 0.001). The loosening rates were 31 % for Hylamer Ogee sockets at 9.4 years, 8 % for Wroblewski Offset Bore sockets at 7.4 years, and 0 % for Charnley Ogee sockets at 5.6 years. No factors were significantly related to acetabular revision and femoral loosening.ConclusionsThe results of Elite Plus stem THA were excellent in the medium term. The cup design was a potential confounding factor for acetabular loosening, and the Hylamer Ogee socket was associated with a poor result.