Background: Rheumatoid arthritis patients with swan neck deformities are postulated to have greater metacarpophalangeal joint arc of motion because of their need to flex the joint to make a fist, whereas the boutonniere deformity places the fingers into the flexed position, creating less demand on the joint for grip. This study analyzes the effect of these deformities on the joint’s arc of motion and hand function.
Methods: The authors measured the metacarpophalangeal joint arc of motion in 73 surgical patients. Data were allocated into groups by finger and hand deformity. Linear regression models were used to analyze the effect of the deformity on the joint’s arc of motion. Functional outcomes were measured by the Michigan Hand Outcomes Questionnaire and the Jebson-Taylor Test.
Results: Nineteen fingers had boutonniere deformity, 95 had swan neck deformities, and 178 had no deformity. The no-deformity group had the least arc of motion at baseline (16 degrees) compared with the boutonniere (26 degrees) and swan neck (26 degrees) groups. Mean arc of motion in the no-deformity group compared with the boutonniere group at baseline was statistically significant, but all groups had similar arc of motion at long-term follow-up. Only mean Jebson-Taylor Test scores at baseline between the boutonniere and no-deformity groups were significantly different.
Conclusions: The results did not support the hypothesis that swan neck deformities have better arc of motion compared with boutonniere deformity. Boutonniere deformity has worse function at baseline, but there was no difference in function among groups at long-term follow-up.
CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.
Ann Arbor, Mich.; Derby, United Kingdom; and Baltimore, Md.
From the Section of Plastic Surgery, Department of Surgery, and the Department of Internal Medicine, Division of Rheumatology, University of Michigan Health System; Center for Statistical Consultation and Research, University of Michigan; Pulvertaft Hand Center; and Curtis National Hand Center.
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Received for publication January 18, 2013; accepted February 27, 2013.
Disclosure: The authors have no financial interest to declare in relation to the content of this article.
Kevin C. Chung, M.D., M.S., Section of Plastic Surgery, University of Michigan Health System, 1500 East Medical Center Drive, 2130 Taubman Center, SPC 5340, Ann Arbor, Mich. 48109-5340, firstname.lastname@example.org