Abstract
Introduction
Up to date there are only few reports in literature on the long term survival of uncemented stems. As for cemented THA, 10 year survival of at least 90% is required for any THA.
Materials and methods
We followed the first 354 consecutive implantations of an uncemented, straight femoral stem (CLS, Zimmer Inc, Warsaw, USA) in 326 patients. Mean time of follow-up evaluation was 17 years (range, 15-20 years).
Results
At follow-up, 84 patients (88 hips) had died, and 12 (12 hips) were lost to follow-up. 34 hips underwent femoral revision: 8 for infection, 8 for periprosthetic fracture, 1 for traumatic loosening and 17 for aseptic loosening of the stem. Overall survival was 89% at 17 years (95%-confidence limits, 87%-92%), survival with femoral revision for aseptic loosening as an end point was 94% at 17 years (95%-confidence limits, 92%-95%). The mean Harris Hip Score at follow-up was 83 points. 220 hips were available for radiolographic evaluation. None of the femoral components showed signs of loosening. Radiolucent lines (<2mm) in Gruen zones 1 and 7 were present in 14.1% (31 hips) and 15.0% (33 hips) respectively. Radiolucencies in zones 2-6 were found in 0.5% (1 hip)-1,8% (4 hips) on ap x-rays. Only one case of distal osteolysis was found after a previous Wagner resurfacing. No case of severe femoral osteolysis was found. The only strong predictor for aseptic loosening was undersizing of the stem with a canal fill index of <75%.
Conclusions
The long-term results for this uncemented stem are encouraging and compare favorably with those achieved in primary cemented total hip arthroplasty in this age group.
