title: Hemiarthroplasty of the elbow: the effect of implant size on joint congruency.
abstract: BACKGROUND
  Distal humeral hemiarthroplasty is a treatment option for elbow joint disease that predominantly affects the distal humerus, including distal humerus fractures, nonunions, and avascular necrosis. The effect of hemiarthroplasty implants on joint contact has not been reported. The purpose of this in vitro study was to quantify the effects of hemiarthroplasty and implant size on ulnohumeral joint congruency.
  
  
  METHODS
  Five fresh frozen cadaveric upper extremities were mounted to a custom elbow testing system. Active and passive motion were performed in dependent, horizontal, varus, and valgus positions. A registration and interbone distance algorithm was used to quantify ulnohumeral joint congruency throughout elbow flexion.
  
  
  RESULTS
  The optimally sized hemiarthroplasty implant demonstrated the greatest joint congruency with the ulna, followed by the oversized implant, then the undersized implant. Joint congruency was greater during active vs. passive flexion, indicating that the elbow joint is more reduced in active flexion than in passive flexion.
  
  
  CONCLUSIONS
  This study demonstrates that undersized distal humeral hemiarthroplasty implants have the lowest joint congruency compared with an optimally sized or oversized implant.
authors.affiliation: Bioengineering Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Department of Surgery, Lawson Research Institute, St. Joseph's Health Care, Western University, London, ON, Canada.
authors.forename: Sagar J
authors.initials: SJ
authors.lastname: Desai
authors.affiliation: Bioengineering Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Department of Surgery, Lawson Research Institute, St. Joseph's Health Care, Western University, London, ON, Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Lalone
authors.affiliation: Bioengineering Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Department of Surgery, Lawson Research Institute, St. Joseph's Health Care, Western University, London, ON, Canada.
authors.forename: George S
authors.initials: GS
authors.lastname: Athwal
authors.affiliation: Bioengineering Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Department of Surgery and Mechanical and Materials Engineering, Lawson Research Institute, St. Joseph's Health Care, Western University, London, ON, Canada.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.affiliation: Bioengineering Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Department of Surgery and Mechanical and Materials Engineering, Lawson Research Institute, St. Joseph's Health Care, Western University, London, ON, Canada.
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
authors.affiliation: Bioengineering Laboratory, Roth|McFarlane Hand and Upper Limb Centre, Department of Surgery, Lawson Research Institute, St. Joseph's Health Care, Western University, London, ON, Canada. Electronic address: gking@uwo.ca.
authors.forename: Graham J W
authors.initials: GJ
authors.lastname: King
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001696:Biomechanical Phenomena; D002102:Cadaver; D004551:Elbow Joint / Q000503:physiopathology* / Q000601:surgery; D004838:Epiphyses; D062785:Hemiarthroplasty / Q000295:instrumentation*; D006801:Humans; D006811:Humerus / Q000503:physiopathology / Q000601:surgery; D007595:Joint Prosthesis; D008297:Male; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D014457:Ulna / Q000503:physiopathology
keywords: Elbow hemiarthroplasty; joint congruency