title: Kinematic and torque-related effects of dorsally angulated distal radius fractures and the distal radial ulnar joint.
abstract: OBJECTIVE
  The purpose of this study was to examine the torque required to achieve a full range of motion of the distal radioulnar joint (DRUJ) as a result of increasing dorsal angulation from simulated fractures of the distal radius. Based on this study the accepted amount of dorsal angulation of the distal radius can be determined.
  
  
  METHODS
  In 9 fresh cadaver limbs motion of the DRUJ was simulated by a custom motion and loading forearm device. The malunion model of the distal radius was controlled by a specially designed external fixation frame that provided control in 6 degrees of dorsal angulations (N, 0 degrees, 10 degrees, 20 degrees, 30 degrees, and 40 degrees ). The study included an intact and nonintact triangular fibrocartilage complex.
  
  
  RESULTS
  This study showed that torque across the DRUJ was affected by the degree of simulated malunion of the distal radius. With more than 30 degrees dorsal angulation the torque across the DRUJ was increased in both muscle loading and unloading conditions. Although significance was not noted, with resistive loading this study showed torque changes with as little as 10 degrees malunion of the distal radius.
  
  
  CONCLUSIONS
  We conclude that reduction of distal radius fractures to within 10 degrees of dorsal angulation is needed to allow patients to maintain full forearm and wrist rotation.
authors.affiliation: Biomechanics Laboratory, Division of Orthopedic Research Mayo Clinic/Foundation, Rochester, MN 55905, USA.
authors.forename: Hirotsune
authors.initials: H
authors.lastname: Hirahara
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Neale
authors.forename: Yu-Te
authors.initials: YT
authors.lastname: Lin
authors.forename: William P
authors.initials: WP
authors.lastname: Cooney
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D017759:Fractures, Malunited / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011403:Pronation / Q000502:physiology; D011885:Radius Fractures / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology*; D019415:Torque; D014457:Ulna / Q000503:physiopathology*; D016474:Weight-Bearing / Q000502:physiology; D014955:Wrist Joint / Q000503:physiopathology*