title: Involvement of the lesser sigmoid notch in elbow fracture dislocations.
abstract: BACKGROUND
  This study addressed the primary null hypothesis that there is no difference in the articular surface area of the lesser sigmoid notch involved among Mayo classes. Secondarily, we analyzed the fracture line location and the pattern of lesser sigmoid notch articular surface involvement among Mayo classes.
  
  
  METHODS
  Using quantitative 3-dimensional computed tomography, we reconstructed and analyzed fractures involving the lesser sigmoid notch articular surface in 52 patients. Further, we assessed the surface area involved in the fracture, the number of fracture fragments, and the location and direction of the fracture lines. Coronoid fractures were classified according to Mayo types.
  
  
  RESULTS
  There was no significant difference between Mayo types 1 and 2 in any characteristic of the involvement of the lesser sigmoid notch articular surface, whereas Mayo type 3 was significantly different from both Mayo types 1 and 2 in the area involved in the fracture (42% in Mayo type 3 vs. 9% in Mayo types 1 and 2), the number of articular fragments (>3 fragments in type 3 vs. 2 fragments in types 1 and 2), and the direction of fracture line (both horizontal and vertical lines in type 3 vs. only horizontal line in types 1 and 2).
  
  
  CONCLUSIONS
  Mayo type III results in a more complex fracture, which might need to be addressed directly or indirectly during open reduction with internal fixation of olecranon fracture dislocations because changes in the geometry of lesser sigmoid notch may affect the radioulnar joint if it remains incongruent.
authors.affiliation: Hand and Upper Extremity Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Orthopedic Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Amir Reza
authors.initials: AR
authors.lastname: Kachooei
authors.affiliation: Hand and Upper Extremity Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Jos J
authors.initials: JJ
authors.lastname: Mellema
authors.affiliation: Hand and Upper Extremity Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Tarabochia
authors.affiliation: Hand and Upper Extremity Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Neal
authors.initials: N
authors.lastname: Chen
authors.affiliation: Department of Orthopaedic Surgery, Academic Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: C Niek
authors.initials: CN
authors.lastname: van Dijk
authors.affiliation: Hand and Upper Extremity Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: david.ring@austin.utexas.edu.
authors.forename: David
authors.initials: D
authors.lastname: Ring
mesh_terms: D003198:Computer Simulation; D004551:Elbow Joint / Q000000981:diagnostic imaging*; D005260:Female; D000072039:Fracture Dislocation / Q000145:classification / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D056740:Olecranon Process / Q000000981:diagnostic imaging / Q000293:injuries; D014057:Tomography, X-Ray Computed; D014458:Ulna Fractures / Q000145:classification / Q000000981:diagnostic imaging*; D000092464:Elbow Injuries
keywords: Mayo; Monteggia; Q3DCT; coronoid; elbow fracture; lesser sigmoid notch; terrible triad; varus posteromedial instability