title: The impact of coronal alignment on distal radioulnar joint stability following distal radius fracture.
abstract: OBJECTIVE
  Shift of the distal fragment of a distal radius fracture (DRF) in the coronal plane (coronal shift) may compromise the contributions of the distal oblique bundle (DOB) of the interosseous membrane to distal radioulnar joint (DRUJ) stability. The purpose of the study was to test our hypothesis that coronal shift of the distal fragment would increase dorsal-volar DRUJ displacement in response to applied load.
  
  
  METHODS
  A distal radius osteotomy was performed proximal to the sigmoid notch base and the ulnar styloid was cut (to simulate triangular fibrocartilage complex detachment) in 10 cadaveric specimens. A volarly placed plate was used to shift the distal radius fragment radially in 2-mm increments. A mechanical testing apparatus applied a 20 N load to the distal fragment perpendicular to the volar cortex with the forearm in neutral, 60° pronation, and 60° supination. Dorsal-volar displacement of the radius relative to the fixed ulna was measured in the control state (DRF and ulnar styloid anatomically fixed) and in 3 positions (anatomical reduction, 2-mm coronal shift, 4-mm coronal shift) with ulnar styloid displacement. The specimens were dissected post hoc to evaluate for a distinct DOB (thickness, > 0.5 mm). Dorsal-volar DRUJ displacement was compared among testing and control states using analysis of variance.
  
  
  RESULTS
  In specimens with a distinct DOB, 2-mm coronal shift significantly increased dorsal-volar DRUJ displacement. However, there was no difference in DRUJ displacement between 4-mm coronal shift and control state. Coronal shift did not affect dorsal-volar DRUJ displacement in specimens without a distinct DOB.
  
  
  CONCLUSIONS
  In the setting of an ulnar styloid fracture, a 2-mm (but not a 4-mm) coronal shift of the DRF is associated with increased dorsal-volar DRUJ displacement in specimens with a distinct DOB, but not in specimens without a distinct DOB.
  
  
  CONCLUSIONS
  Awareness of the importance of coronal shift may aid in prevention of DRUJ instability associated with DRF, especially in patients with a DOB.
authors.affiliation: Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Dy
authors.affiliation: Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Eugene
authors.initials: E
authors.lastname: Jang
authors.affiliation: Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Taylor
authors.affiliation: Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Kathleen N
authors.initials: KN
authors.lastname: Meyers
authors.affiliation: Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY. Electronic address: wolfes@HHS.edu.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D017760:Bone Malalignment / Q000150:complications / Q000517:prevention & control; D001860:Bone Plates; D002102:Cadaver; D019245:Compressive Strength; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D057072:Intra-Articular Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D011859:Radiography; D011885:Radius Fractures / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D012680:Sensitivity and Specificity; D051478:Triangular Fibrocartilage / Q000000981:diagnostic imaging / Q000601:surgery*; D014955:Wrist Joint / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult
keywords: Distal interosseous membrane; coronal shift; distal oblique bundle; distal radioulnar joint; distal radius