title: Effect of Volarly Angulated Distal Radius Fractures on Forearm Rotation and Distal Radioulnar Joint Kinematics.
abstract: OBJECTIVE
  To examine the effect of volar angulation deformities of the distal radius with and without triangular fibrocartilage complex (TFCC) rupture on forearm range of motion and the kinematics of the ulnar head at the distal radioulnar joint (DRUJ) during simulated active forearm rotation.
  
  
  METHODS
  Volar angulation deformities of the distal radius with 10° and 20° angulation from the native orientation were created in 8 cadaveric specimens using an adjustable apparatus. Active supination and pronation were performed using a forearm motion simulator. Pronation and supination range of motion was quantified with each deformity. In addition, changes in the dorsovolar position of the ulnar head relative to the radius were calculated after simulating each distal radial deformity. Testing was performed with the TFCC intact and sectioned.
  
  
  RESULTS
  Volar angulation deformities of 20° decreased the supination range with preservation of pronation. There was no effect of TFCC status on the range of forearm rotation. With the TFCC intact, volar angulation deformities translated the ulna slightly dorsally in pronation and volarly in supination. After sectioning the TFCC, volar angulation deformities of 10° and 20° translated the ulna dorsally throughout forearm rotation.
  
  
  CONCLUSIONS
  Volar angulation deformities reduce supination range and alter the DRUJ kinematics. The increased tension in the intact TFCC caused by volar angulation deformities likely prevented the expected dorsovolar displacement at the DRUJ and restricted supination. Dividing the TFCC released the constraining effect on the DRUJ and allowed the ulna to translate dorsally. However, supination remained limited, presumably because of impediment from the dorsally subluxated ulna.
  
  
  CONCLUSIONS
  This study demonstrated the importance of correcting volar angulation deformities of the distal radius to less than 20° in order to maintain normal range of forearm rotation and to less than 10° to maintain normal DRUJ kinematics when the TFCC is ruptured.
authors.affiliation: Department of Orthopaedic Surgery, Kawasaki Municipal Hospital, Kawasaki, Japan. Electronic address: nishiwa41@gmail.com.
authors.forename: Masao
authors.initials: M
authors.lastname: Nishiwaki
authors.affiliation: Hand and Upper Limb Centre, St. Joseph's Health Care London, London, Ontario, Canada.
authors.forename: Mark F
authors.initials: MF
authors.lastname: Welsh
authors.affiliation: Division of Orthopaedic Surgery, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Braden
authors.initials: B
authors.lastname: Gammon
authors.affiliation: Hand and Upper Limb Centre, St. Joseph's Health Care London, London, Ontario, Canada.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.affiliation: Hand and Upper Limb Centre, St. Joseph's Health Care London, London, Ontario, Canada.
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
authors.affiliation: Hand and Upper Limb Centre, St. Joseph's Health Care London, London, Ontario, Canada.
authors.forename: Graham J W
authors.initials: GJ
authors.lastname: King
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005542:Forearm / Q000503:physiopathology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011403:Pronation; D011885:Radius Fractures / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D013484:Supination; D014457:Ulna / Q000503:physiopathology*; D014955:Wrist Joint / Q000503:physiopathology*
keywords: Distal radioulnar joint; distal radius fracture; kinematics; triangular fibrocartilage complex; volar angulation