title: Biomechanical comparison between the trapezius transfer and latissimus transfer for irreparable posterosuperior rotator cuff tears.
abstract: BACKGROUND
  The purpose of this study was to characterize the biomechanical effects of the lower trapezius transfer and to compare it with the latissimus dorsi transfer in a cadaveric model of a massive posterosuperior rotator cuff tear.
  
  
  METHODS
  Eight cadaveric shoulders were tested at 0°, 30°, and 60° of shoulder abduction. Range of motion, humeral rotational position due to muscle loading, joint reaction forces, and kinematics were measured. All specimens were tested in 4 conditions: intact, massive posterosuperior cuff tear, lower trapezius transfer, and latissimus dorsi transfer. A repeated-measures analysis of variance was used for statistical analysis.
  
  
  RESULTS
  Internal rotation due to muscle loading increased with massive cuff tear compared with the intact condition (P < .05). The latissimus transfer corrected this change at 0° abduction, whereas the trapezius transfer corrected this at all abduction angles. The massive cuff tear decreased glenohumeral joint compression forces at all abduction angles; these forces were restored by the lower trapezius transfer (P < .05). At maximum humeral internal rotation and 0° of abduction, the humeral head apex shifted superiorly and laterally with massive cuff tear (P < .05); this shift was more closely restored to intact values by the trapezius transfer compared with the latissimus transfer (P < .05).
  
  
  CONCLUSIONS
  The lower trapezius transfer is superior to the latissimus transfer at restoring native glenohumeral kinematics and joint reaction forces in our cadaveric model. It may be a promising treatment option for patients with a massive irreparable rotator cuff tear.
authors.affiliation: Department of Orthopaedic Surgery, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Omid
authors.affiliation: Department of Orthopaedic Surgery, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: Nathanael
authors.initials: N
authors.lastname: Heckmann
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, Long Beach, CA, USA.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Wang
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, Long Beach, CA, USA.
authors.forename: Michelle H
authors.initials: MH
authors.lastname: McGarry
authors.affiliation: Department of Orthopaedic Surgery, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
authors.forename: C Thomas
authors.initials: CT
authors.lastname: Vangsness
authors.affiliation: Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, Long Beach, CA, USA; Department of Orthopaedic Surgery, University of California, Irvine, CA, USA. Electronic address: tqlee@med.va.gov.
authors.forename: Thay Q
authors.initials: TQ
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D058430:Humeral Head / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D012399:Rotation; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D012785:Shoulder Joint / Q000503:physiopathology* / Q000601:surgery; D064171:Superficial Back Muscles / Q000601:surgery*
keywords: Massive rotator cuff tear; biomechanical study; cadaver study; latissimus dorsi transfer; trapezius transfer