Survival, clinical and radiological outcome of the Zweymüller SL/Bicon-Plus total hip arthroplasty: a 15-year follow-up study.

Abstract

The primary aim of this study is to analyse the long-term results of the third generation of the "Zweymüller" total hip arthroplasty (THA) comprising the SL-Plus Stem and the Bicon-Plus cup. We evaluated 208 patients with a SL/Bicon-Plus primary THA (218 hips). Survival analysis was performed with a follow-up of 13 to 15 years. Complementary clinical and radiological analysis was performed using the "Hip Injury and Osteoarthritis Outcome Score" (HOOS) and x-rays of the hips. The probability of survival of the stem and cup with revision for any reason was respectively 0.96/0.97 at 10 years and 0.92/0.94 at 15 years. The probability of survival of the stem and cup with revision for aseptic loosening was respectively 0.99/0.97 at 10 years and 0.95/0.94 at 15 years. Clinical assessment of the patients, reported by the HOOS, were scored with a median for the subdivisions: symptoms 90%, pain 93%, function in daily activity 87%, function in leisure or sport 75%, and quality of life with 75%. Periprosthetic radiolucent lines were observed in half of all hips in Gruen zones 1 and 7. Mean linear wear of the polyethylene was 1.8 mm which corresponds to 0.12 mm/year. 2/3 of the hips show heterotopic ossifications, mostly Brooker type 1 and 2. The "third generation" Zweymüller total hip arthroplasty consisting of the SL stem and the Bicon cup has good long term results in terms of survival, clinical and radiological outcome.