title: Relative contributions of the ulnar attachments of the triangular fibrocartilage complex to the dynamic stability of the distal radioulnar joint.
abstract: OBJECTIVE
  Laboratory studies evaluating the importance of the stabilizing structures of the distal radioulnar joint (DRUJ) largely have been limited to static design. Clinically, dynamic loading seems to be an important component of DRUJ instability. This study was designed to evaluate the influence of dynamic loading on the stability of the DRUJ with foveal versus styloid triangular fibrocartilage complex (TFCC) disruptions in a laboratory setting.
  
  
  METHODS
  Twelve fresh-frozen cadaveric upper-extremity specimens were tested using a dynamic simulator to study the contributions of the 2 ulnar insertions of the TFCC to the dynamic stability of the DRUJ. The specimens were tested in 3 loading conditions (no load, agonist loading, antagonist loading) in 3 different states of the TFCC (intact, foveal disruption, styloid disruption).
  
  
  RESULTS
  Without load no significant differences were found for the different conditions of the TFCC. Under loaded conditions the foveal insertion had a greater effect on stability than did the styloid insertion. Under agonist loading significant differences were found during supinating and pronating motions. With antagonist loading a significant difference was found only during supination.
  
  
  CONCLUSIONS
  The study results support the clinical impression that dynamic loading is an important component of DRUJ instability and that disruption of the foveal TFCC insertion into the foveal region of the distal ulna can produce instability.
authors.affiliation: Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Jan-Ragnar
authors.initials: JR
authors.lastname: Haugstvedt
authors.forename: Richard A
authors.initials: RA
authors.lastname: Berger
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Nakamura
authors.forename: Patricia
authors.initials: P
authors.lastname: Neale
authors.forename: Lawrence
authors.initials: L
authors.lastname: Berglund
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
mesh_terms: D000368:Aged; D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000502:physiology; D011403:Pronation / Q000502:physiology; D011884:Radius / Q000502:physiology; D013484:Supination / Q000502:physiology; D051478:Triangular Fibrocartilage / Q000502:physiology / Q000601:surgery*; D014457:Ulna / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology; D014955:Wrist Joint / Q000502:physiology*