Long-Term Results (Minimum of 20 Years) of a Pure Proximal-Loading Metaphyseal-Fitting Anatomic Cementless Stem Without Distal Stem Fixation in Hip Arthroplasty.

Abstract

There are no reported results for more than 20 years of a pure proximal-loading anatomic cementless femoral stem without diaphyseal stem fixation. The purpose of this study was to evaluate the long-term (minimum 20 years) clinical results, bone remodeling, revision rate, and survivorship of these implants in patients aged less than 60 years. We included 523 patients (657 hips), including 319 men and 204 women. The mean body mass index was 26.7 (range, 23-29 kg/m²). The mean age of patients at index surgery was 55 years (range, 20-59 years). The Harris Hip Score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the University of California, Los Angeles activity score were recorded preoperatively and at each follow-up. Mean follow-up was 23.5 years (range, 20-27 years). The Harris Hip Score at the final follow-up was a mean 93 points (range, 70-100 points). The Western Ontario and McMaster Universities Osteoarthritis Index and University of California, Los Angeles activity scores at the final follow-up were 16 and 7.6 points, respectively. Five femoral components (0.8%) and 13 acetabular components (2.0%) were revised. All cases in the current series had grade 2 stress shielding; no hips had grade 3 or 4 stress shielding. Kaplan-Meier survivorship of the implants at 23.5 years was 98.0% (95% confidence interval 92%-100%) for the acetabular component and 99.2% (95% confidence interval 93%-100%) for the femoral component. A pure proximal-loading metaphyseal-fitting anatomic cementless stem with alumina-on-alumina ceramic bearing couples functioned well, with no osteolysis or mild stress-shielding at an average 23.5-year follow-up.