Cementless Lord total hip arthroplasty: Cup loosening common after minimum 10-year follow-up of 103 hips

We evaluated the clinical and radiographic results of 103 (88 patients) cementless Lord total hip arthroplasty after a mean follow-up period of 12.5 (10-16) years. 77 hips had arthrosis, 15 rheumatoid arthritis and 11 osteonecrosis. The preoperative mean Harris Hip Score improved from 47 (19-66) to 87 (62-99) at 5 years, but declined to 77 (56-97) at the final examination. The survivorship of the cup, using radiographically confirmed aseptic loosening as the end point, was 63% at 10 years and 45% at 15 years and the survivorship of the stem was 97% at 10 years and 96% at 15 years. The low figures of the cup may be due to insufficient contact between the smooth-surfaced threads of the cup and the acetabular bone. Thinner polyethylene, insufficient initial bone coverage, and larger femoral head diameter were significantly related to the occurrence of loosening. We can not recommend this smooth-surfaced threaded cup because of its high failure.