Minimum ten-year follow-up clinical and radiographic results of Mark I and Mark II Lord type femoral component in total hip arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results in 103 hips in 88 patients who had cementless primary Lord type femoral component (stem), with a mean follow-up of 11.8 years (range, 10 to 16 years). The original diagnoses were: osteoarthritis in 77 hips, rheumatoid arthritis in 15, and osteonecrosis of the femoral head in 11. Clinical results were assessed using the Harris hip score. Biological fixation, stem full-fit ratio in the intramedullary canal, and bone remodeling were evaluated by X-ray findings. The average clinical hip scores were: 47.1 points preoperatively, 81.7 points at 1 year, 86.6 points at 5 years, 79.0 points at 10 years, and 76.8 points at 15 years. By setting the endpoint at the time when loosening was radiologically confirmed, the 10-year survivorship of the femoral component was 96.9%, and the 16-year survivorship was 95.9%. The full-fit ratio between the bone implant interface just after surgery showed a significant relationship to stability of the femoral component. The decrease in the hip score at 10 years was caused by aseptic loosening of the acetabular threaded cup. However, the femoral component was stable for more than 10 years after the operation. In conclusion, long-term acceptable durability can be expected with the Lord type femoral component.