Long-Term Results of Charnley Low Friction Arthroplasty for Ankylosing Spondylitis

Abstract

The authors determined the long-term results of 95 Charnley low friction arthroplasties performed on 58 patients with ankylosing spondylitis. The average age at the time of operation was 39.7 years (range, 19 - 70 years) and average duration of follow-up was 19 years (range, 10–30 years). All patients had substantial relief of pain, improvement of function, and range of motion of the joint, and 55 patients (95%) were completely free of pain. Twelve acetabular and nine femoral components were revised for aseptic loosening at an average of 13.9 years (range, 4.2 - 20 years) with 79 original femoral components (83%) and 78 acetabular components (82%) remaining in situ. Six femoral and eight acetabular components were radiologically loose and a total of 20 acetabular components (21%) and 15 femoral implants (16%) had loosened aseptically.There was no heterotopic ossification in 71 hips (75%), with 22 hips (23%) having minor changes (Brooker Class I or 2), two hips (2%) having clinically important ossification (Class 3) and none having reankylosis. Survivorship of the acetabular component (with 95% confidence intervals) was 92% at 10 years (87% - 98%), 85% at 15 years (77% - 93%), and 77% at 25 years (67% - 87%). Femoral implant survivorship at the same time intervals was 90% (84% - 96%), 87% (79% - 94%), and 77% (80% - 99%), respectively. Charnley low friction arthroplasty provided good long-term results in this series of young and active patients, without the increased risk of the development of heterotopic ossification and reankylosis that has been reported previously.