title: In vivo kinematics of the thumb carpometacarpal joint during three isometric functional tasks.
abstract: BACKGROUND
  The thumb carpometacarpal (CMC) joint is often affected by osteoarthritis--a mechanically mediated disease. Pathomechanics of the CMC joint, however, are not thoroughly understood due to a paucity of in vivo data.
  
  
  OBJECTIVE
  We documented normal, in vivo CMC joint kinematics during isometric functional tasks. We hypothesized there would be motion of the CMC joint during these tasks and that this motion would differ with sex and age group. We also sought to determine whether the rotations at the CMC joint were coupled and whether the trapezium moved with respect to the third metacarpal.
  
  
  METHODS
  Forty-six asymptomatic subjects were CT-scanned in a neutral position and during three functional tasks (key pinch, jar grasp, jar twist), in an unloaded and a loaded position. Kinematics of the first metacarpal, third metacarpal, and the trapezium were then computed.
  
  
  RESULTS
  Significant motion was identified in the CMC joint during all tasks. Sex did not have an effect on CMC joint kinematics. Motion patterns differed with age group, but these differences were not systematic across the tasks. Rotation at the CMC joint was generally coupled and posture of the trapezium relative to the third metacarpal changed significantly with thumb position.
  
  
  CONCLUSIONS
  The healthy CMC joint is relatively stable during key pinch, jar grasp, and jar twist tasks, despite sex and age group.
  
  
  CONCLUSIONS
  Our findings indicate that directionally coupled motion patterns in the CMC joint, which lead to a specific loading profile, are similar in men and women. These patterns, in addition to other, nonkinematic influences, especially in the female population, may contribute to the pathomechanics of the osteoarthritic joint.
authors.affiliation: Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA.
authors.forename: Eni
authors.initials: E
authors.lastname: Halilaj
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rainbow
authors.forename: Christopher
authors.initials: C
authors.lastname: Got
authors.forename: Joel B
authors.initials: JB
authors.lastname: Schwartz
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Moore
authors.forename: Arnold-Peter C
authors.initials: AP
authors.lastname: Weiss
authors.forename: Amy L
authors.initials: AL
authors.lastname: Ladd
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Crisco
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena; D052737:Carpometacarpal Joints / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D018737:Hand Strength; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D050279:Metacarpal Bones / Q000000981:diagnostic imaging / Q000502:physiology; D008875:Middle Aged; D009068:Movement; D011857:Radiographic Image Interpretation, Computer-Assisted; D016059:Range of Motion, Articular; D012737:Sex Factors; D013933:Thumb / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D051222:Trapezium Bone / Q000000981:diagnostic imaging / Q000502:physiology; D016474:Weight-Bearing; D055815:Young Adult