title: The effect of swan neck and boutonniere deformities on the outcome of silicone metacarpophalangeal joint arthroplasty in rheumatoid arthritis.
abstract: 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.
authors.affiliation: 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.
authors.forename: Matthew
authors.initials: M
authors.lastname: Chetta
authors.forename: Patricia B
authors.initials: PB
authors.lastname: Burns
authors.forename: H Myra
authors.initials: HM
authors.lastname: Kim
authors.forename: Frank D
authors.initials: FD
authors.lastname: Burke
authors.forename: E F Shaw
authors.initials: EFS
authors.lastname: Wilgis
authors.forename: David A
authors.initials: DA
authors.lastname: Fox
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D019643:Arthroplasty, Replacement / Q000295:instrumentation; D005260:Female; D005500:Follow-Up Studies; D006227:Hand Deformities, Acquired / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D007595:Joint Prosthesis; D016014:Linear Models; D008297:Male; D008662:Metacarpophalangeal Joint / Q000503:physiopathology / Q000601:surgery*; D008875:Middle Aged; D015233:Models, Statistical; D011446:Prospective Studies; D016059:Range of Motion, Articular; D012828:Silicones; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
chemical_list: D012828:Silicones