title: The effect of a coronoid prosthesis on restoring stability to the coronoid-deficient elbow: a biomechanical study.
abstract: OBJECTIVE
  The coronoid process has been recognized as a critical component in maintaining elbow stability. In the case of comminuted coronoid fractures, where repair is not possible or has failed, a prosthesis may be beneficial in restoring the osseous integrity of the elbow joint. The hypothesis of this in vitro biomechanical study was that a coronoid prosthesis would restore stability to the coronoid-deficient elbow.
  
  
  METHODS
  An anatomically shaped metallic coronoid prosthesis was designed and developed based on computed tomography-derived measurements and optimized to account for average cartilage thickness. Elbow kinematics and stability were determined for 8 cadaveric arms in active and passive elbow flexion in the varus, valgus, horizontal, and vertical positions using an elbow motion simulator. Varus-valgus angulation and internal-external rotation of the ulna relative to the humerus were quantified in the intact state, after collateral ligament sectioning and repair (control state), after a simulated 40% transverse coronoid fracture, and after implantation of the coronoid prosthesis.
  
  
  RESULTS
  Internal rotation of the ulna increased with a 40% coronoid fracture in the horizontal and varus positions. Increases in varus angulation after coronoid fracture were also observed in the horizontal and varus positions, during active and passive flexion, respectively. Following implantation of the coronoid prosthesis, elbow kinematics were restored similar to control levels in all elbow positions.
  
  
  CONCLUSIONS
  Our findings support our hypothesis that an anatomically shaped coronoid prosthesis would be effective in restoring stability to the coronoid-deficient elbow.
  
  
  CONCLUSIONS
  This study provides evidence that the use of an anatomical implant restores stability to the coronoid-deficient elbow and rationale for further study and development of this method. For comminuted coronoid fractures, where repair is not possible or has failed, our research indicates that a prosthesis may be a feasible treatment option.
authors.affiliation: Hand and Upper Limb Center, University of Western Ontario, London, Ontario, Canada. agray@qmed.ca
authors.forename: Alia B
authors.initials: AB
authors.lastname: Gray
authors.forename: Bashar
authors.initials: B
authors.lastname: Alolabi
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.forename: George S
authors.initials: GS
authors.lastname: Athwal
authors.forename: Graham J W
authors.initials: GJ
authors.lastname: King
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D004550:Elbow / Q000503:physiopathology; D058569:Elbow Prosthesis; D005260:Female; D005542:Forearm; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000601:surgery*; D008023:Ligaments, Articular / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D014458:Ulna Fractures / Q000601:surgery*; D000092464:Elbow Injuries
keywords: Coronoid; biomechanics; elbow; fracture; prosthesis