Glenohumeral Joint Acute Posterior Dislocation

Epidemiology

  • Rare
  • 2% of acute dislocations
  • Often missed
  • Diagnosis
< 1/ 5225%
1- 6/5225%
> 6/52-6/1225%
> 6/1225%

Aetiology

  • Usually 2° major trauma
    • MVA
    • Seizures
    • ECT
    • Electrocution
    • Alcohol-related injuries

History

  • Of injury
  • Pain & stiffness

Examination

  • Loss of ER
  • IR 40°
  • Hold arm across chest
  • Beware of young patient with arm across chest & limited ROM & don’t think frozen shoulder only

Investigations

XRays

  • AP
    • Light-bulb sign
    • Globular head 2° IR
  • Axillary Lateral
    • May see Reverse Hill- Sachs

CT Scan

  • Confirms dislocation
  • Quantifies humeral head defect
  • Locked dislocation

Treatment

  • Depends on
    1. Duration of dislocation
    2. Size of humeral head defect

Reduction

  • Indication
    • Duration < 6 weeks
    • Defect < 20 -30 %
  • Technique
    • GA
    • Closed Traction with ↑ IR to unlock head
    • May require open reduction
  • unstable closed reduction
    • abduction brace or gunslinger cast to hold in neutral or slight ER (ie stop IR)

Stabilisation

  • Indications
    • Duration < 1 yr
    • Hill Sach Defect < 25- 40% of head
    • Hill Sach < 25% Leave

Technique

  • McLaughlin Procedure
    • Deltopectoral approach
    • Lesser Tuberosity with attached Subscapularis transferred into Reverse Hill-Sachs lesion
    • Renders defect an extra-articular problem

Hemiarthroplasty

  • Indications
    • Duration > 1 years
    • Defect HS > 40%
    • Ie Too big for Stabilizaton
  • Contraindicaton
    • Avoid in young
  • Technique
    • Placed in Neutral (cf Retroversion)
    • To ↓ incidence of posterior instability

Osteochondral Allograft

  • Gerber 1996 JBJS
  • Allograft placed into defect
  • indication
    • < 40%
    • young patient

Rotational osteotomy

  • Keppler J Ortho Trauma 94