Changes in Bone Mineral Density After Joint Replacement of Lower Extremities in Patients with Rheumatoid Arthritis.

In order to know the changes of bone mineral density in patients with rheumatoid arthritis (RA) after joint replacement of the lower extremities, we examined 10 RA patients (1 male and 9 females, average age 59.4) who underwent joint replacement of the knee joint and/or hip joint. We measured the bone mineral density of the lumbar spine, radius at 1/3 distal end and calcaneus by the method of Dual Energy X-ray Absorptiometry (DEXA) with different time processes, pre- and post-operation of 18 to 57 months. The patients showed severe walking disability before operation, and improvement after. After the operation, the bone mineral density increased both in the lumbar spine and calcaneus, but decreased in the radius. These results demonstrate that calcaneus is influenced by weight bearing, especially in joint replacement. Furthermore, this improvement in walking affects total body activity, resulting in increased bone mineral density of the lumbar spine.