title: Capitellum fractures: a biomechanical evaluation of three fixation methods.
abstract: OBJECTIVE
  To determine the relative stability of three fixation methods for displaced capitellum fractures.
  
  
  METHODS
  Twelve matched pairs of embalmed humeri were divided into two equal groups and simulated capitellum fractures created. The first group compared cancellous lag screws placed in an anteroposterior direction to screws placed in the posteroanterior direction. The second group compared the Acutrac compression screw, inserted anteroposteriorly, to the more stable construct from the first test group.
  
  
  METHODS
  All specimens were cyclically tested with simulated physiologic loading. Both displacement of the capitellum over a range of cycles and the number of cycles to failure were recorded.
  
  
  RESULTS
  Fixation with posteroanteriorly directed cancellous lag screws was significantly more stable than anteroposteriorly directed screws at 2000 cycles (p = 0.007); loads to failure were not statistically different. Fixation by the Acutrac screws was significantly more stable than posteroanterior cancellous screws at 2000 cycles (p = 0.03). The Acutrac fixation had a higher failure load; however, this was not statistically significant.
  
  
  CONCLUSIONS
  The headless screws tested in this biomechanical study provided more stable fixation of capitellum fractures in the cadaveric specimens than four-millimeter partially threaded cancellous lag screws and may do so in the clinical setting. When the cancellous lag screws were tested, insertion in the posteroanterior direction provided more stable fixation than the anteroposterior direction and has clinical benefit of not violating the articular surface. Ultimately, the decision of which method to use lies with the attending surgeon and the technique with which he or she feels most comfortable.
authors.affiliation: Department of Orthopedic Surgery, New York University Hospital for Joint Diseases, New York, New York, USA.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Elkowitz
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Polatsch
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Egol
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Kummer
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Koval
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D004551:Elbow Joint / Q000503:physiopathology* / Q000601:surgery; D005592:Fracture Fixation; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D006810:Humeral Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011859:Radiography; D016474:Weight-Bearing / Q000502:physiology; D000092464:Elbow Injuries