Abstract
Purpose
Ceramic-on-ceramic bearings in total hip arthroplasty (CoC THA) have theoretical advantages of wear resistance and favorable biocompatibility of ceramic particles to the surrounding bony and soft tissue. Long-time durability of CoC THA has been expected, however, clinical results over 10 years after operation were scarcely reported. In the present study, clinical results at follow of 10 years were examined for CoC THAs with a changeable femoral neck which allowed correction of anteversion of the femoral component in cases with abnormal femoral anteversion in dysplastic hips.
Methods
During 1997 and 2000, 203 cementless CoC THAs in 158 patients were conducted in our hospital. Six patients died because of unrelated causes and 5 patients were lost to followup, and the remaining 188 hips in 147 patients were analyzed at the mean followup period of 10.8 years (3.7 to 13.5). There were 24 men and 123 women, and the average age at operation was 54 years (26 to 73). The hip diseases for operation were osteoarthritis in 165 hips, osteonecrosis of the femoral head in 21 hips and failure of hemiarthroplasty in 2 hips. The operation was performed in the lateral position through the posterior approach without trochanteric osteotomy. The articulation was composed of Biolox forte alumina liner fitted into beads-coated hiemispherical titanium shell, and a 28-mm Biolox forte alumina femoral head (Cremascoli). The femoral component was either AnCA stem or custom-designed stem, coupled with a modular neck allowing selection of 5 variable offsets and anteversions (Cremascoli). Clinical and radiological findings, and complications during the followup period were analyzed.
Results
During the follow-up, 8 hips were revised, due to repeated dislocation (2 hips), periprosthetic fracture (1 hips), cup loosening (1 hip), fracture of ceramic liner rim (2 hips), and cup loosening along with ceramic liner rim fracture (2 hips). Cup abduction angle of the 4 cases with ceramic liner rim fracture were high at 49 degrees or more, as compared with the mean cup abduction angle of 41 degrees in the other hips without ceramic fracture. The survival rate at 10 years was 96.0 % when failure was revision. In the hips other than the revised cases, 6 hips showed cup loosening and no hip showed stem loosening on radiographs. Osteolysis was seen in 3 hips around the cup and 4 hips around the stem. Nineteen patients (10%) complained of abnormal noises around the hip, but most of the noises were click sound.
Discussion
The 10-year results of cementless CoC THAs with a modular neck were favorable with few cases of osteolysis. However, relatively high frequency of cup loosening may be a concern, since increased cup abduction angle associated with cup loosening may cause ceramic liner fracture.
