Cementless primary total hip prostheses with a third-generation alumina-on-alumina bearing showed very low wear and were associated with minimal osteolysis at the time of follow-up, at a minimum of five years.

We studied 33 third generation, alumina ceramic-on-ceramic bearings retrieved from cementless total hip replacements after more than six months in situ. Wear volume was measured with a Roundtest machine, and acetabular orientation from the anteroposterior pelvic radiograph. The overall median early wear rate was 0.1 mm(3)/yr for the femoral heads, and 0.04 mm(3)/yr for the acetabular liners. We then excluded hips where the components had migrated. In this stable subgroup of 22 bearings, those with an acetabular anteversion of < 15 degrees (seven femoral heads) had a median femoral head wear rate of 1.2 mm(3)/yr, compared with 0 mm(3)/yr for those with an anteversion of > or =15 degrees (15 femoral heads, p < 0.001). Even under edge loading, wear volumes with ceramic-on-ceramic bearings are small in comparison to other bearing materials. Low acetabular anteversion is associated with greater wear.

We performed 33 cementless total hip arthroplasties for arthritis in 27 patients with an established diagnosis of Paget's disease on the acetabular or femoral side of the hip. There were 3 revisions. One stem for aseptic loosening at 55 months, and 2 stems after periprosthetic fractures at 9 and 70 months. Twenty-three cases were available for follow-up at an average of 6.7 years (range, 2-14 years). Harris hip score improved from 56/100 preoperatively (16-98/100) to 90/100 postoperatively (78-100/100). All surviving components were radiographically bone ingrown. Based on our findings, it appears that a cementless total hip arthroplasty can have a good outcome in Paget's disease.

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