The affect of rheumatoid arthritis can progress to the degree that it is crippling. Deformities distinctive to late-stage rheumatoid arthritis such as ulnar deviation of the bones of the hands, or swan-neck deviation of the fingers occur because muscles and tendons on one side of the joint may overpower those on the other side, pulling the bones out of alignment.
Review Date: 1/16/2016
Reviewed By: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.