The involvement of bone in
rheumatoid arthritis (RA) is well recognized, and hand bone densitometry appears to be a promising new technique to monitor
disease progression by assessing serial changes in hand bone mass in patients with RA. New
biochemical markers of bone formation (i.e.
osteocalcin) show contradictory results in different studies, although markers of
bone resorption (i.e. urinary
collagen cross-links) have shown significant increase in patients with RA. Bone histomorphometric studies suggest that the periarticular
osteopenia in RA could be related to increased bone turnover locally, whereas generalized
osteoporosis could be due to a global negative remodelling balance. The important factors implicated in the pathogenesis of the bone loss are circulating
cytokines [e.g. tumour
necrosis factor alpha (
TNF alpha),
interleukin (IL) 1 and
IL6] produced by the inflammatory process, use of oral
corticosteroids (in the dose of > or = 5 mg) and reduced mobility due to functional impairment. Apart from this underlying
osteoporosis, patients with RA have an increased risk of falls secondary to functional impairment and there is an increased risk of fractures in patients with RA. Very few studies are presently available looking at the therapeutic measures to prevent
osteoporosis in RA. Future
drug trials on the treatment of RA should include bone mass measurement, especially of the hand, as one of the outcome measures.