title: First dorsal interosseous muscle contraction results in radiographic reduction of healthy thumb carpometacarpal joint.
abstract: BACKGROUND
  Hand therapists selectively strengthen the first dorsal interosseus (FDI) to stabilize arthritic joints yet the role of the FDI has not yet been radiographically validated.
  
  
  OBJECTIVE
  To determine if FDI contraction reduces radial subluxation (RS) of the thumb metacarpal (MC).
  
  
  METHODS
  Fluoroscopy was used to obtain true anterior-posterior radiographs of non-arthritic CMC joints: 1) at rest, 2) while stressed and 3) while stressed with maximal FDI contraction. Maximal FDI strength during CMC stress and thumb MC RS and trapezial articular width were measured. The ratio of RS to the articular width was calculated.
  
  
  RESULTS
  Seventeen participants (5 male, 12 female) participated. Subluxation of a stressed CMC significantly reduced and the subluxation to articular width ratio significantly improved after FDI activation.
  
  
  CONCLUSIONS
  Contraction of the FDI appears to radiographically reduce subluxation of the healthy thumb CMC joint. Further exploration on the FDI's reducibility and its carry-over effects in arthritic thumbs is needed.
  
  
  METHODS
  4.
authors.affiliation: University of Minnesota, Program in Occupational Therapy, 300 University Square, 111 South Broadway, Rochester, MN 55904, USA. Electronic address: mcge0062@umn.edu.
authors.forename: Corey
authors.initials: C
authors.lastname: McGee
authors.affiliation: University Orthopaedics Therapy Center, Fairview, 2450 Riverside Ave., Suite R102, Minneapolis, MN 55454, USA.
authors.forename: Virginia
authors.initials: V
authors.lastname: O'Brien
authors.affiliation: University of Minnesota, Department of Orthopaedic Surgery, 2450 Riverside Ave. South, Suite 200, Minneapolis, MN 55454, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Van Nortwick
authors.affiliation: Mayo Clinic, Department of Orthopedic Surgery, 200 First St. SW, Rochester, MN 55905, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Adams
authors.affiliation: University of Minnesota, Department of Orthopaedic Surgery, 2450 Riverside Ave. South, Suite 200, Minneapolis, MN 55454, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Van Heest
mesh_terms: D000328:Adult; D052737:Carpometacarpal Joints / Q000000981:diagnostic imaging* / Q000502:physiology; D005260:Female; D005471:Fluoroscopy; D018737:Hand Strength / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D013314:Stress, Mechanical; D013933:Thumb; D051222:Trapezium Bone / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Carpometacarpal; First dorsal interosseous; Hand therapy; Osteoarthritis; Strength