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 1/21/2020
Updated by: Gordon A. Starkebaum, MD, MACR, ABIM Board Certified in Rheumatology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.