Structural mechanisms of bone loss in iliac biopsies: comparison between rheumatoid arthritis and postmenopausal osteoporosis.

To assess the mechanisms that cause generalized osteoporosis in rheumatoid arthritis (RA), 40 postmenopausal women with RA (46-74 years) and 40 age-matched controls with osteopenia underwent iliac bone biopsies. A structural analysis of histomorphometry and two-dimensional strut analysis were performed. As compared to those with primary osteoporosis, there were a few unique characteristics in those with RA. Trabecular thickness and wall thickness declined with age, and this decline was especially accelerated by glucocorticoids. Decreased connectivity of the trabecular (Nd.Nd) was more prominent than the disappearance of the nodes. The connectivity of cortical bone to the nodes (Ct.Nd) and cortical thickness significantly decreased with age. With glucocorticoid therapy, the disappearance of the nodes was accelerated. In the case of vertebral compression fractures, the parameters of Nd.Nd and Ct.Nd significantly decreased. Although a bone biopsy is needed to analyze strut, this method is useful to evaluate the quality or intensity of the bone.