title: Anterior shoulder dislocation increases the propensity for recurrence: a cadaveric study of the number of dislocations and type of capsulolabral lesion.
abstract: BACKGROUND
  The number of anterior shoulder dislocations that predispose to recurrence is unknown; some clinicians recommend surgical repair after the initial episode and others after multiple recurrences. The purpose of this study was to quantify the forces during successive anterior dislocations of cadaveric shoulders and to inspect the capsule and labrum afterwards, in order to assess the propensity for recurrence.
  
  
  METHODS
  Twenty-two human cadaveric shoulders were tested using a custom cadaveric shoulder dislocation device with simulated muscle loading. Each was positioned in the apprehension position and the humerus was moved in horizontal abduction until the shoulder dislocated. The joint reaction force was measured, as was the force that developed passively in the pectoralis major muscle. Following 3 successive dislocations, each was inspected for anterior capsulolabral lesions.
  
  
  RESULTS
  There was a significant decrease in force after the second dislocation. In 11, there was no labral avulsion and a significant decrease in force after the first dislocation. In the other 11, there was a labral avulsion and a significant decrease in force after the second dislocation.
  
  
  CONCLUSIONS
  Two successive anterior shoulder dislocations may increase propensity for recurrence; but this is influenced by the type of capsulolabral lesion that occurs. No labral avulsion, likely a result of capsular stretching, may be a worse prognostic finding than labral avulsion after the initial episode.
authors: Orthopaedic Biomechanics Laboratory, Veterans Affairs Healthcare System, Long Beach, CA, USA. mcmahonp@upmc.edu
authors: Patrick J
authors: PJ
authors: McMahon
authors: Bruce Y
authors: BY
authors: Yang
authors: Stephen
authors: S
authors: Chow
authors: Thay Q
authors: TQ
authors: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D006801:Humans; D017746:Joint Capsule / Q000473:pathology*; D016059:Range of Motion, Articular; D012008:Recurrence; D012307:Risk Factors; D012783:Shoulder Dislocation / Q000209:etiology* / Q000473:pathology*; D016474:Weight-Bearing
keywords: Bankart; Basic Science Study; Biomechanics; Cadaver Model; Shoulder; cadaver; capsule; dislocation; model; recurrence; stretch; successive