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Journal Club

July 2010

Pathoanatomy of First Time, Traumatic, Anterior Glenohumeral Subluxation Events

• Authors: Owens CB, Nelson BJ, Duffey ML, Mountcastle SB, Taylor DC, Cameron KL, Campbell S, DeBerardino TM.
• Institution: Keller Army Hospital, West Point, NY, USA
• Journal: J Bone Joint Surg Am. 2010 Jul;92(7):1605-11.

Abstract link

No outside funding

Introduction

• Attempt to define the pathoanatomy of 1st time, traumatic, anterior glenohumeral subluxation

Methodology

• Anterior shoulder subluxation events defined as
  
  • Incomplete instability events not requiring manual reduction
    
  • Diagnosed in patients with
    
    • A painful shoulder event and feeling of transient instability
      
    • Anterior apprehension, relief with relocation, anterior translation on load-sift testing
• Prospective evaluation 2004-2005
  • Closed cohort military cadets
  • Included only those with a 1st time, traumatic event who had undergone MRI within 2 weeks of the injury
• Evaluation included:
  • Demographics
    
  • Mechanism of injury
    
  • Examination findings
    
  • Plain XR
    
  • MRI
    
    • Hill Sachs
      
    • Bankart
      
  • Surgical findings
• Follow up
  
  • Cadet Illness and Injury Tracking System
    
  • Armed Forces Health Longitudinal Technology Application medical record
    
  • Phone/email
    
  • Recurrent instability/return to activit

Results

• Total cohort 4141
  
  • 38 events over 1 academic year
    
    • 27 included in study
      
    • 11 excluded as did not have MRI in first 2 weeks
      
  • 22 men, 5 women
    
    • Mean age 20 (18-24)
      
    • Hand dominance
      • 13 dominant, 10 non-dominant, 4 unknown
• Activities
  
  • Boxing 10
    
  • Indoor obstacle course 7
    
  • Rugby 5
    
  • Skiing
    
  • Snowboarding
    
  • Football
    
  • Cheerleading
    
  • Military training
• Mechanism
  
  • Fall 5
    
  • Tackle 5
    
  • Missed punches 5
• Plain XR
  
  • 3 bony Bankart
    
  • 2 Hill Sachs
• MRI
  
  • 26 Bankart (6 bony)
    
  • 25 Hill Sachs
• Management
  
  • 10 patients arthroscopic Bankart repair within 3 months
    
  • 4 went onto repair after experiencing recurrent instability
    
  • Of this 14
    • 13 had a Bankart lesion at the time of surgery
      
    • ie 1 Bankart lesion on MRI not confirmed at OR
• 13 patients managed non-operatively
  
  • 4 recurrent instability
    
  • 2 lost to follow up
    
  • 7 back to active duty

Discussion

• Dislocation well studied with subluxation events disproportionately under evaluated
• 85% of instability events actually subluxations that do not require manual reduction (Owens 2007)
• Subluxation events have similarly high rates of both Bankart and Hill Sachs lesions
  • Therefore current classification of instability events is not adequate – developed a new aspect of classification termed transiient luxation
• Transient luxations
  
  • Complete dislocation with spontaneous reduction
    
  • Evidenced by Bankart and Hill Sachs
• Implication for management
  
  • More likely to go onto recurrent instability
• A number of papers looking at presence of Hill Sachs and Bankart lesions in anterior shoulder subluxation
  
  • All high
    
  • Mostly in recurrent instability
• No other study evaluating pathological changes in 1st time, traumatic anterior subluxation
• Study Conclusions
  
  • Subluxation events are common
    
  • High rate of pathological changes in traumatic, first time, anterior subluxations
    
  • Presence of Hill Sachs and Bankart lesions on MRI may indicate a spontaneously reducing dislocation
    
  • These injuries should be termed transient luxations
    
  • MRI is a useful prognostic tool in such events

Pros of Study

• Strengths
  Prospective
  Numbers
  MRI within 2 weeks

Cons of Study

• Follow up