title: Volar subluxation of the ulnar head in dorsal translation deformities of distal radius fractures: an in vitro biomechanical study.
abstract: OBJECTIVE
  To quantify the effects of dorsal translation deformities of the distal radius with and without dorsal angulation on volar displacement of the ulnar head during simulated active forearm rotation, both with the triangular fibrocartilage complex (TFCC) intact and sectioned conditions.
  
  
  METHODS
  Eight fresh-frozen cadaveric upper extremities were mounted in an active forearm motion simulator, and distal radial deformities of 0, 5, and 10 mm of dorsal translation with 0, 10, 20, and 30 degrees of dorsal angulation were simulated. Volar displacement of the ulnar head at the distal radioulnar joint as a result of each distal radial deformity was quantified during simulated active supination. The data were collected with the TFCC intact and after sectioning the TFCC at its ulnar insertion.
  
  
  RESULTS
  Increasing isolated dorsal translation deformities increased volar displacement of the ulnar head when the TFCC was intact (P < 0.001). Increasing dorsal translation combined with dorsal angulation increased volar displacement of the ulnar head compared with isolated dorsal angulation deformities (P < 0.001). Sectioning the TFCC increased the volar displacement of the ulnar head caused by each distal radial deformity (P = 0.001).
  
  
  CONCLUSIONS
  These results emphasize the clinical importance of evaluating the magnitude of both dorsal translation and dorsal angulation when managing displaced distal radius fractures and malunions.
authors.affiliation: *Department of Orthopaedic Surgery, Kawasaki Municipal Hospital, Kawasaki, Japan; †Hand and Upper Limb Center, St Joseph's Health Care London, London, Ontario, Canada; and ‡Division of Orthopaedic Surgery, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Masao
authors.initials: M
authors.lastname: Nishiwaki
authors.forename: Mark
authors.initials: M
authors.lastname: Welsh
authors.forename: Braden
authors.initials: B
authors.lastname: Gammon
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
authors.forename: Graham J W
authors.initials: GJ
authors.lastname: King
mesh_terms: D002102:Cadaver; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011885:Radius Fractures / Q000503:physiopathology*; D016059:Range of Motion, Articular; D014457:Ulna / Q000293:injuries* / Q000503:physiopathology*; D014954:Wrist Injuries / Q000503:physiopathology*