Periarticular bone in rheumatoid arthritis versus arthrosis. Histomorphometry in 103 hip biopsies.

Histomorphologic differences of the periarticular bone in rheumatoid arthritis (RA) and osteoarthrosis (OA) may be of importance for long-term prosthetic fixation. We have evaluated bone specimens, obtained during total hip replacement from an acetabular and a femoral biopsy site, in 42 RA-hips and 61 OA-hips. In both groups the bone turnover was increased in the acetabulum compared to that in the femur. In the acetabulums the total trabecular bone volume was equal, but osteoid volume, osteoid surface, resorptive surface, and the appositional rate were increased in RA. On the femoral side, only the osteoid volume was higher in RA. The increased bone turnover with a greater amount of unmineralized tissue, as well as resorptive activity in the acetabulum, may be of importance for the higher rate of acetabular component migration and loosening after total hip replacement in RA.