title: In Vivo kinematics of the trapeziometacarpal joint during thumb extension-flexion and abduction-adduction.
abstract: OBJECTIVE
  The primary aim of this study was to determine whether the in vivo kinematics of the trapeziometacarpal (TMC) joint differ as a function of age and sex during thumb extension-flexion (Ex-Fl) and abduction-adduction (Ab-Ad) motions.
  
  
  METHODS
  The hands and wrists of 44 subjects (10 men and 11 women with ages 18-35 y and 10 men and 13 women with ages 40-75 y) with no symptoms or signs of TMC joint pathology were imaged with computed tomography during thumb extension, flexion, abduction, and adduction. The kinematics of the TMC joint were computed and compared across direction, age, and sex.
  
  
  RESULTS
  We found no significant effects of age or sex, after normalizing for size, in any of the kinematic parameters. The Ex-Fl and Ab-Ad rotation axes did not intersect, and both were oriented obliquely to the saddle-shaped anatomy of the TMC articulation. The Ex-Fl axis was located in the trapezium and the Ab-Ad axis was located in the metacarpal. Metacarpal translation and internal rotation occurred primarily during Ex-Fl.
  
  
  CONCLUSIONS
  Our findings indicate that normal TMC joint kinematics are similar in males and females, regardless of age, and that the primary rotation axes are nonorthogonal and nonintersecting. In contrast to previous studies, we found Ex-Fl and Ab-Ad to be coupled with internal-external rotation and translation. Specifically, internal rotation and ulnar translation were coupled with flexion, indicating a potential stabilizing screw-home mechanism.
  
  
  CONCLUSIONS
  The treatment of TMC pathology and arthroplasty design require a detailed and accurate understanding of TMC function. This study confirms the complexity of TMC kinematics and describes metacarpal translation coupled with internal rotation during Ex-Fl, which may explain some of the limitations of current treatment strategies and should help improve implant designs.
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI; Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, Providence, RI; Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA. Electronic address: joseph_crisco@brown.edu.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Crisco
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI; Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, Providence, RI; Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA.
authors.forename: Eni
authors.initials: E
authors.lastname: Halilaj
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI; Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, Providence, RI; Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA.
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Moore
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI; Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, Providence, RI; Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA.
authors.forename: Tarpit
authors.initials: T
authors.lastname: Patel
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI; Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, Providence, RI; Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA.
authors.forename: Arnold-Peter C
authors.initials: AP
authors.lastname: Weiss
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI; Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, Providence, RI; Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Ladd
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology*; D052737:Carpometacarpal Joints / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D012737:Sex Factors; D014057:Tomography, X-Ray Computed; D051222:Trapezium Bone / Q000502:physiology*; D055815:Young Adult
keywords: ROM; TMC; Thumb; in vivo; kinematics