title: In Vivo Contact Characteristics of Distal Radioulnar Joint With Malunited Distal Radius During Wrist Motion.
abstract: OBJECTIVE
  To determine whether distal radioulnar joint (DRUJ) contact characteristics were altered in patients with malunited distal radius fractures.
  
  
  METHODS
  We obtained computed tomography scans at 5 positions of both wrists of 6 patients who had unilateral malunited distal radius fractures with dorsal angulation from 10° to 20° and ulnar variance less than 3 mm. We reconstructed 3-dimensional images and mapped contact regions of DRUJ by calculating the shortest distance between the 2 opposing bones. The contact areas of the DRUJ were measured and the contact region centers were calculated and analyzed. The values of the malunited side were compared with those of the contralateral uninjured side.
  
  
  RESULTS
  In the uninjured wrist, the contact areas of the DRUJ increased slightly from wrist flexion to extension and ulnar deviation. In the malunited wrist, we found the contact areas of DRUJ to be progressively reduced from 20° flexion to neutral, 40° extension, and 20° extension, to ulnar deviation. The centroid of this area on the sigmoid notch moved to distal from flexion to extension. Compared with the contralateral uninjured wrist, the contact area significantly decreased during wrist extension and ulnar deviation, and significantly increased during wrist flexion. The centroids of this area on sigmoid notch all moved volarly in all selected wrist positions.
  
  
  CONCLUSIONS
  The contact areas of the DRUJ and the centroid of contact area on sigmoid notch are altered in patients with malunited distal radius fractures. The contact area of the DRUJ increases during wrist flexion and decreases during wrist extension and ulnar deviation. The centroids of the contact area on sigmoid notch move volarly during wrist flexion-extension and ulnar deviation.
  
  
  CONCLUSIONS
  The in vivo findings suggest that alterations in joint mechanics may have an important role in the dysfunction associated with these injuries.
authors.affiliation: Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu.
authors.forename: Shu Guo
authors.initials: SG
authors.lastname: Xing
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong, China.
authors.forename: Yan Rong
authors.initials: YR
authors.lastname: Chen
authors.affiliation: Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu.
authors.forename: Ren Guo
authors.initials: RG
authors.lastname: Xie
authors.affiliation: Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu. Electronic address: jinbotang@yahoo.com.
authors.forename: Jin Bo
authors.initials: JB
authors.lastname: Tang
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D017759:Fractures, Malunited / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011884:Radius / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011885:Radius Fractures / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D014057:Tomography, X-Ray Computed; D014457:Ulna / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014955:Wrist Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*
keywords: 3-dimensional; Distal radioulnar joint; contact characteristics; in vivo; malunited distal radius fracture