title: Load transfer at the distal ulna following simulated distal radius fracture malalignment.
abstract: OBJECTIVE
  To measure the effects of distal radius malalignment on loading at the distal ulna.
  
  
  METHODS
  Using an adjustable mechanism to simulate angulated and translated malalignments, clinically relevant distal radius deformities were simulated in a cadaveric model. A custom-built load cell was inserted just proximal to the native ulna head to measure the resultant force and torque in the distal ulna. Loads were measured before and after transecting the triangular fibrocartilage complex (TFCC).
  
  
  RESULTS
  There was an increase in distal ulna load and torque with increasing dorsal translation and angulation. Combined conditions of angulation and translation increased force and torque in the distal ulna to a greater extent than with either condition in isolation. Transecting the TFCC resulted in a reduction in distal ulna load and torque.
  
  
  CONCLUSIONS
  A progressive increase in load at the distal ulna was observed with increasing severity of malalignment, which may be an important contributor to residual ulnar wrist pain and dysfunction. However, no clear-cut threshold of malalignment of a dorsally angulated and translated distal radius fracture was identified. These observations suggest that radius deformities cause articular incongruity, which increases TFCC tension and distal radioulnar joint load. Cutting of the TFCC decreased distal ulna loading, likely by releasing the articular constraining effect of the TFCC on the distal radioulnar joint, allowing the radius to rotate more freely with respect to the ulna.
  
  
  CONCLUSIONS
  Anatomical reduction of a distal radius fracture minimizes the forces in the distal ulna and may reduce residual ulnar wrist pain and dysfunction.
authors.affiliation: Bioengineering Research Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada; Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada; Department of Biomedical Engineering, Western University, London, Ontario, Canada; Department of Surgery, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.affiliation: Bioengineering Research Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada; Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada; Department of Biomedical Engineering, Western University, London, Ontario, Canada; Department of Surgery, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada.
authors.forename: Gillian S
authors.initials: GS
authors.lastname: Greeley
authors.affiliation: Bioengineering Research Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada; Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada; Department of Biomedical Engineering, Western University, London, Ontario, Canada; Department of Surgery, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada.
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
authors.affiliation: Bioengineering Research Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada; Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada; Department of Biomedical Engineering, Western University, London, Ontario, Canada; Department of Surgery, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada. Electronic address: gking@uwo.ca.
authors.forename: Graham J W
authors.initials: GJ
authors.lastname: King
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology*; D005260:Female; D017759:Fractures, Malunited / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011885:Radius Fractures / Q000503:physiopathology*; D019415:Torque; D051478:Triangular Fibrocartilage / Q000503:physiopathology; D014457:Ulna / Q000503:physiopathology*; D016474:Weight-Bearing / Q000502:physiology*; D014954:Wrist Injuries / Q000503:physiopathology*
keywords: DRUJ; distal radius; distal ulna; fracture malalignment; joint loads