title: In vivo length changes of carpal ligaments of the wrist during dart-throwing motion.
abstract: OBJECTIVE
  The dart-throwing motion is an important movement pattern during most wrist actions. The aim of this study was to investigate length changes in the wrist ligaments in different positions of the dart-throw motion in vivo.
  
  
  METHODS
  We obtained computed tomography scans of the wrists of 6 volunteers at 5 positions of the wrist during the dart-throw motion: 20° of radial deviation with 60° of extension; 10° of radial deviation with 30° of extension; the neutral position of the carpus; 20° of ulnar deviation with 30° of flexion; and 40° of ulnar deviation with 60° of flexion. We reconstructed the 3-dimensional carpal and distal radioulnar joint structures with customized software and computed changes in length of 8 palmar and dorsal wrist ligaments.
  
  
  RESULTS
  From wrist radial deviation with extension to ulnar deviation with flexion, the radioscaphocapitate, long radiolunate, ulnocapitate, and ulnotriquetral ligaments decreased significantly in length but the dorsal radiocarpal ligament and the dorsal intercarpal (DIC) ligament inserting on the trapezoid lengthened significantly; the ulnolunate ligament and the DIC ligament inserting on the scaphoid were shortest in neutral position.
  
  
  CONCLUSIONS
  At wrist radial extension, the radioscaphocapitate, long radiolunate, ulnocapitate, and ulnotriquetral ligaments are lengthened and under increased tension. At wrist ulnar flexion, the dorsal radiocarpal ligament and the DIC ligament inserting on the trapezoid are lengthened and under increased tension. The ulnolunate ligament and the DIC ligament inserting on the scaphoid are the shortest and under the least tension in neutral position. These findings will help us understand the biomechanics of the carpus during the dart-throwing motion.
authors.affiliation: Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China. jinbotang@yahoo.com
authors.forename: Jin Bo
authors.initials: JB
authors.lastname: Tang
authors.forename: Xiao Kun
authors.initials: XK
authors.lastname: Gu
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Jian Hui
authors.initials: JH
authors.lastname: Gu
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D050824:Carpal Joints / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D008023:Ligaments, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000502:physiology; D008875:Middle Aged; D009038:Motion; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D012494:Sampling Studies; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014955:Wrist Joint / Q000000981:diagnostic imaging* / Q000502:physiology*