title: Elbow kinematics after radiocapitellar arthroplasty.
abstract: OBJECTIVE
  Radiocapitellar arthroplasty has been proposed as a reconstructive option for combined radial head and capitellar deficiency. The purpose of this study was to assess the impact of radiocapitellar replacement on elbow kinematics. We hypothesized that with the medial collateral ligament (MCL) intact, radiocapitellar arthroplasty would replicate normal kinematics, and that a radiocapitellar arthroplasty would more closely approximate normal kinematics than an elbow with a deficient lateral column or with a deficient MCL.
  
  
  METHODS
  We tested 7 cadaveric arms in an upper extremity joint simulator. Each arm underwent computed tomographic scanning to aid implant size selection and computer-assisted implant insertion. We obtained kinematic data using an electromagnetic tracking system during elbow flexion. The capitellar and radial head implants were placed through an extended lateral epicondylar osteotomy. We sectioned the anterior bundle of the MCL, leaving the flexor-pronator mass intact. Outcomes of interest were varus-valgus and rotational kinematics of the ulnohumeral joint.
  
  
  RESULTS
  The radiocapitellar arthroplasty showed no difference in kinematics compared with the postosteotomy control. The MCL-deficient elbow showed more valgus angulation and more external ulnar rotation than the control or radiocapitellar arthroplasty in the pronated, valgus loaded position. The deficient lateral column demonstrated increased external ulnar rotation kinematics during active elbow flexion.
  
  
  CONCLUSIONS
  Radiocapitellar arthroplasty can restore normal elbow kinematics with the MCL intact. If the MCL is deficient, radiocapitellar arthroplasty does not restore normal kinematics.
  
  
  CONCLUSIONS
  Radiocapitellar arthroplasty should be considered in cases of lateral column deficiency because it maintains normal elbow kinematics during active motion. Whereas radiocapitellar arthroplasty improves the stability of the MCL-deficient elbow with deficiency of the lateral column, reconstruction of the MCL may further improve normal kinematics.
authors.affiliation: St Joseph's Health Care, University of Western Ontario, London, Ontario, Canada.
authors.forename: M T
authors.initials: MT
authors.lastname: Sabo
authors.forename: H
authors.initials: H
authors.lastname: Shannon
authors.forename: S
authors.initials: S
authors.lastname: De Luce
authors.forename: E
authors.initials: E
authors.lastname: Lalone
authors.forename: L M
authors.initials: LM
authors.lastname: Ferreira
authors.forename: J A
authors.initials: JA
authors.lastname: Johnson
authors.forename: G J W
authors.initials: GJ
authors.lastname: King
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001178:Arthroplasty / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D017885:Collateral Ligaments / Q000503:physiopathology / Q000601:surgery; D004551:Elbow Joint / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011884:Radius / Q000503:physiopathology / Q000601:surgery*; D016059:Range of Motion, Articular; D012399:Rotation; D014057:Tomography, X-Ray Computed