Histomorphometry of periarticular bone in rheumatoid arthritis

Periarticular osteoporosis is a common feature of rheumatoid arthritis. However, the cellular basis and the aetiology of periarticular bone loss have not been established. We studied periarticular bone samples obtained from metatarsal resections (n = 18) and total knee arthroplasties (n = 9) by histomorphometry. Autopsy material (n = 10) and patients with osteoarthrosis (n = 11) served as controls. Histomorphometrically, there was reduced trabecular bone volume and increased resorption surfaces in rheumatoid arthritis patients in most of the measured areas. The indices of bone turnover were most markedly increased in the vicinity of inflammatory cells and rheumatoid granulation tissue. Trabecular bone volume and the degree of inflammation as measured by the erythrocyte sedimentation rate (ESR) had a negative correlation. In addition, an elevated ESR was associated with increased osteoid parameters in periarticular bone. We conclude that periarticular bone loss in rheumatoid arthritis is due to increased bone resorption. Local inflammatory mediators might account for the increased bone turnover.