Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology.

The objective of this article is to summarize current understanding of biomechanical factors that cause ulnar drift in the hands of patients with rheumatoid arthritis. This was done through literature review of published articles on the mechanical etiology of ulnar drift. There are several theories regarding the cause of ulnar drift, however conclusive evidence is still lacking. Current mechanical factors that are postulated to play a role include: failure of the collateral ligaments, intra-articular pressure changes, degenerative changes in the carpal and metacarpal anatomy, muscle hypoxia induced changes in wrist tension, and exacerbating activities of daily living. Although current theories regarding ulnar drift almost universally include an at least partially mechanical rationale, the causes may be multifactorial. Significantly more research is needed to elucidate the relative importance of mechanical factors leading to significant ulnar drift concurrent with advanced rheumatoid arthritis.