Shoulder dislocation

The glenohumeral joint is the most often dislocated large joint: a big head on a small, shallow glenoid, held mainly by soft tissue. Most dislocations are anterior. The young re-dislocate (labrum torn off: Bankart), the older tear the rotator cuff or break the greater tuberosity.

Mechanism

Anterior: fall or tackle with the arm abducted and externally rotated. Posterior: seizure, electric shock, fall on the outstretched arm in internal rotation. Inferior: hyperabduction.

Clinical findings

• Squared-off shoulder, arm held away from the body, cannot rotate.
• Before and after reduction: axillary nerve (sensation over the regimental badge area, deltoid contraction), radial pulse and hand neurology.
• Over about 40: test the rotator cuff once the pain settles.
• Posterior dislocation: arm locked in internal rotation, cannot externally rotate. Easily missed.

Imaging

• AP in the scapular plane plus a Y view or axillary view: always two planes, before and after reduction.
• Look for a greater tuberosity or glenoid rim fracture, and a fracture of the humeral neck (do not try to reduce a fracture-dislocation in the emergency room).
• After a first dislocation in the young or with a large bony lesion: CT; MRI arthrogram for labrum and cuff.

Classification

Direction

Anterior (subcoracoid, subglenoid, subclavicular), posterior, inferior (luxatio erecta).

Hill–Sachs

Posterolateral humeral head impaction from the glenoid rim.

Bankart

Anteroinferior labrum (soft) or rim fracture (bony) torn off the glenoid.

Fracture-dislocation

With greater tuberosity, surgical neck or anatomical neck fracture (see proximal humerus).

Types shown in 3D

Anterior (subcoracoid)

About 95% of shoulder dislocations. The head comes out in front of the glenoid and comes to lie under the coracoid; the arm is held slightly abducted and externally rotated, the shoulder looks squared off.

Posterior

Rare (2–4%) and often missed: after epileptic seizures and electric shocks. The arm is locked in internal rotation; the AP view shows the "lightbulb" head and an empty anterior glenoid. Always get an axillary or Y view.

Inferior (luxatio erecta)

The head is levered below the glenoid with the arm locked straight overhead. High rate of axillary nerve and artery injury and of rotator cuff tears or greater tuberosity fractures.

Anterior + greater tuberosity

In patients over about 40 the cuff often pulls off the greater tuberosity instead of tearing. The fragment usually reduces with the head; it needs fixation if it stays displaced more than about 5 mm.

Anterior + bony Bankart

The head shears off the anterior-inferior rim of the glenoid. A large rim fragment (more than about 20% of the glenoid width) leaves the shoulder unstable: fix it or reconstruct the glenoid (Latarjet).

Treatment

Reduction

Analgesia/sedation, then a gentle technique: external rotation (Kocher’s first step only), Cunningham massage, FARES or traction–countertraction; Hippocratic method only gently. Check neurovascular status and repeat the X-ray.

After a first dislocation

Sling for comfort 1–3 weeks, then physiotherapy. Young active patients (high recurrence) or a large bony Bankart: consider early arthroscopic Bankart repair or Latarjet.

Fracture-dislocation

Displaced greater tuberosity (> 5 mm): fixation. Neck fracture with dislocation: reduction in theatre and fixation or arthroplasty in the elderly.

Posterior / chronic

Closed reduction under anaesthesia; large reverse Hill–Sachs lesions need McLaughlin procedure, grafting or arthroplasty.

Aftercare

Physiotherapy for rotator cuff and scapular control; avoid abduction–external rotation for 6 weeks after a first anterior dislocation.

Complications

• Recurrence (up to 80–90% under 20 years old)
• Axillary nerve palsy
• Rotator cuff tear (older patients)
• Missed posterior dislocation
• Fracture during reduction (iatrogenic neck fracture)