title: The effect of capitellar impaction fractures on radiocapitellar stability.
abstract: OBJECTIVE
  To determine the effect of capitellar impaction fractures on radiocapitellar stability in a model that simulated a terrible triad injury.
  
  
  METHODS
  Six cadaveric elbows were dissected free of skin and muscles. Tendons were preserved. The lateral collateral ligament was released and repaired (surgical control). Two sizes of capitellar impaction defects were created. After lateral collateral ligament release and repair, we then sequentially created osseous components of a terrible triad injury (partial radial head resection and coronoid fracture) through an olecranon osteotomy that was fixed with a plate. Radiocapitellar stability was recorded after the creation of each new condition.
  
  
  RESULTS
  Significantly less force was required for radiocapitellar subluxation after the creation of 20° and 40° capitellar defects compared with the surgical control (intact capitellum). After the addition of a Mason type II radial head defect and then a coronoid defect, stability decreased significantly further.
  
  
  CONCLUSIONS
  Impaction fractures of the distal portion of the capitellum may contribute to a loss of radiocapitellar stability, particularly in an elbow fracture-dislocation.
  
  
  CONCLUSIONS
  Because these injuries may be unrecognized, consideration should be given to diagnosing and addressing them.
authors.affiliation: Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN.
authors.forename: Dave R
authors.initials: DR
authors.lastname: Shukla
authors.affiliation: Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Thoreson
authors.affiliation: Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN.
authors.forename: James S
authors.initials: JS
authors.lastname: Fitzsimmons
authors.affiliation: Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN.
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
authors.affiliation: Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN. Electronic address: odriscoll.shawn@mayo.edu.
authors.forename: Shawn W
authors.initials: SW
authors.lastname: O'Driscoll
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001863:Bone Screws; D002102:Cadaver; D004210:Dissection; D004551:Elbow Joint / Q000601:surgery*; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D057072:Intra-Articular Fractures / Q000601:surgery*; D004204:Joint Dislocations / Q000601:surgery; D007593:Joint Instability / Q000517:prevention & control*; D008297:Male; D011885:Radius Fractures / Q000601:surgery*; D013314:Stress, Mechanical; D000092464:Elbow Injuries
keywords: Capitellum impaction; elbow fracture-dislocation; terrible triad