Key Facts

Dislocations are time-critical emergencies requiring prompt reduction to prevent complications including neurovascular injury, avascular necrosis (particularly hip), and chronic instability. Knowledge of reduction techniques and associated injuries is essential.

Epidemiology

Shoulder dislocations are the most common large joint dislocation (incidence ~24 per 100,000 per year). Young men (sports) and elderly women (falls) are most commonly affected. Hip dislocations are less common but are orthopaedic emergencies. Finger/thumb dislocations are the most common overall.

Aetiology

• Traumatic: Falls, sports injuries (shoulder), RTCs/dashboard injury (hip), contact sports
• Atraumatic: Hypermobility syndromes (Ehlers-Danlos, Marfan's), recurrent dislocators
• Associated injuries: Fracture-dislocations require different management approach

Pathophysiology

A dislocation occurs when the articular surfaces of a joint are completely displaced. Subluxation is partial displacement. The direction of dislocation depends on the mechanism of force and the anatomy of the joint. Associated injuries include ligamentous damage, labral tears, fractures, and neurovascular injury due to stretching or compression of adjacent structures.

Anterior Shoulder Dislocation

• Arm held in slight abduction and external rotation
• Loss of normal shoulder contour; squared-off appearance
• Palpable humeral head anteriorly; empty glenoid posteriorly
• Axillary nerve: Test regimental badge area sensation, deltoid contraction

Posterior Shoulder Dislocation (Rare ~5%)

• Associated with epileptic seizure, electrocution, or direct anterior force
• Arm held in adduction and internal rotation; cannot externally rotate
• Often MISSED on AP X-ray — lightbulb sign; axillary or Y-view confirms

Posterior Hip Dislocation

• Leg shortened, adducted, internally rotated, flexed
• Dashboard mechanism (knee hits dashboard, force transmitted along femur)
• Sciatic nerve at risk (foot drop)
• AVN of femoral head if not reduced within 6h

Other Common Dislocations

• Elbow: Posterior most common; ulnar nerve at risk
• Patella: Lateral dislocation; often reduces spontaneously
• Finger (DIPJ/PIPJ): Dorsal most common; check for volar plate injury
• Lunate/perilunate: Wrist dislocation; median nerve compression

Red Flags

• Absent distal pulse — vascular emergency; reduce immediately
• Progressive neurological deficit — urgent reduction
• Hip dislocation — reduce within 6h to minimise AVN risk
• Open dislocation — surgical emergency
• Fracture-dislocation — may require surgical reduction

Bedside

• Neurovascular assessment: Before AND after reduction — document formally
• Mechanism of injury: Guide imaging and associated injury assessment

Imaging

• Pre-reduction X-ray: 2 views minimum — confirm dislocation, identify associated fracture (unless limb-threatening vascular compromise → reduce first)
• Post-reduction X-ray: Confirm concentric reduction
• CT: Complex fracture-dislocations (hip, knee, elbow); surgical planning
• MRI: Ligamentous/labral assessment post-reduction (shoulder — Bankart/SLAP lesions; knee — ligaments)
• CT angiography: If knee dislocation — mandatory vascular assessment (30-40% popliteal artery injury)

Special Tests

• Ankle-brachial pressure index (ABPI): Post-knee dislocation — if <0.9, angiography required
• Apprehension test: Post-shoulder reduction — assess for instability

Shoulder Reduction Techniques

• External rotation method: Slow, gentle external rotation with elbow at 90° — good for anterior
• Cunningham technique: Patient seated; massage trapezius, deltoid, biceps — atraumatic
• Stimson (hanging weight): Patient prone, arm hanging off bed, 5kg weight
• Hippocratic method: Axial traction with counter-traction; foot in axilla (historical, less used)
• Kocher's method: Traction, external rotation, adduction, internal rotation

Hip Reduction

• Emergency reduction under GA/sedation: Within 6 hours to reduce AVN risk
• Bigelow method (posterior dislocation): Patient supine; hip and knee flexed to 90°; longitudinal traction along femur with internal rotation
• Stimson method: Patient prone; hip and knee flexed over bed edge; downward pressure on calf

Pharmacological

• Procedural sedation: Midazolam 1-2mg + fentanyl 50-100mcg IV; OR propofol 0.5-1mg/kg IV; OR entonox for simple dislocations
• Intra-articular local anaesthetic: 10-20mL lidocaine 1% into shoulder joint — effective for anterior shoulder reduction
• Post-reduction analgesia: Paracetamol + NSAID + opioid as needed

Post-Reduction

• Shoulder: Broad arm sling for 2-4 weeks; avoid abduction and external rotation; physiotherapy
• Hip: Non-weight-bearing; CT post-reduction (exclude intra-articular fragments); orthopaedic follow-up
• Elbow: Above-elbow backslab at 90° for 2-3 weeks; early ROM

Surgical/Interventional

• Failed closed reduction: Open reduction under GA
• Fracture-dislocation: Often requires surgical fixation
• Recurrent shoulder instability: Arthroscopic Bankart repair or Latarjet procedure
• Knee dislocation with vascular injury: Emergency vascular repair

Referral Criteria

• Failed closed reduction — orthopaedic emergency
• Fracture-dislocation — orthopaedic assessment (may need surgery)
• Neurovascular compromise — urgent surgical assessment
• Hip dislocation — orthopaedic emergency (<6h target)
• Knee dislocation — vascular surgery assessment (CT angiography)

• Anterior shoulder: Recurrence ~60-90% in <20 years; ~10% in >40 years; surgical stabilisation reduces recurrence to <10%
• Posterior hip: AVN risk ~10-20% overall; increases significantly if reduction delayed >6h (up to 50%)
• Knee dislocation: High rate of multi-ligament injury; popliteal artery injury in 30-40% — can lead to amputation if missed
• Elbow: Good prognosis with closed reduction; 'terrible triad' requires surgery and carries higher complication rate
• Long-term: Recurrent instability, post-traumatic arthritis, stiffness are common sequelae depending on joint and injury severity

Shoulder Dislocation — Associated Injuries by Age

Procedural Sedation Requirements

Knee Dislocation — Mandatory Assessment