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

Background: 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. Methods: 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). Results: 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. Conclusion: 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.