Summary

The Glenohumeral joint is the most commonly dislocated major joint in the body (45%) due to its inherent instability (large ball, small socket). Anterior Dislocation accounts for 95% of cases, typically from forced abduction and external rotation. Management involves acute reduction and assessment for associated pathology: Bankart Lesion (labrum tear) and Hill-Sachs Lesion (humeral head impact fracture). The risk of recurrence is inversely proportional to age: >90% in teenagers vs <10% in patients over 40. Young athletes with bone loss usually require the Latarjet Procedure (coracoid transfer) for stabilization. [1,2,3]

Key Facts

• Most Common Mechanism: Abduction + External Rotation (e.g., throwing, tackling).
• Most Common Nerve Injury: Axillary Nerve (5-10%). Test sensation over the lateral deltoid ("Regimental Badge").
• The "Lightbulb Sign": In Posterior Dislocation (e.g., seizures/electrocution), the head is locked in Internal Rotation. On the AP X-ray, it looks circular (like a lightbulb) because you don't see the greater tuberosity profile.
• Recurrence Rule:
  • Age <20: ~90% recurrence.
  • Age 20-40: ~50% recurrence.
  • Age >40: <10% recurrence (But high risk of Rotator Cuff Tear).

Clinical Pearls

"The Axillary View is King": You cannot reliably rule out a posterior dislocation on an AP view alone. If the patient cannot abduct for a true axillary view, use the Velpeau view (leaning back over table).

"Cunningham Technique": A reduction method requiring NO sedation. You sit opposite the patient, massage their biceps/trapezius to relax the spasm, and ask them to shrug and retract shoulders. The head slips back in. "Bore them to reduction".

"The Elderly Dislocator": If a patient >40 dislocates, they have likely TORN their Rotator Cuff (Massive Tear). If they can't lift their arm 2 weeks later, it's not the nerve—it's the cuff. MRI is mandatory.

                 SHOULDER DISLOCATION
                        ↓
             ACUTE? RECURRENT? DIRECTION?
             ┌──────────┴──────────┐
           ACUTE               RECURRENT
             ↓                     ↓
        X-RAY (Exclude #)       BONE LOSS?
             ↓                 ┌────┴────┐
         REDUCTION            NO        YES
    (Kocher/Stimson/FARES)  (Soft)    (Bony)
             ↓                 ↓         ↓
         IMMOBILISE         BANKART   LATARJET
        (Sling 1-2w)        REPAIR   PROCEDURE
             ↓
        AGE GROUPS?
    ┌───────┼───────┐
  <20     20-40    >40
(High Risk)   (Med)   (Cuff Risk)
    ↓         ↓       ↓
PHYSIO?    PHYSIO   MRI
 SURGERY?           (Check Cuff)

Techniques

1. Kocher's Method: (Traction -> External Rotation -> Adduction -> Internal Rotation). Risk of spiral fracture if forced.
2. Hippocratic: Foot in axilla. (Historical - Do Not Use - Nerve injury risk).
3. Stimson's: Prone, weight hanging from arm. Slow (20 mins).
4. FARES Method: Oscillating the arm up and down while abducting. Very effective.
5. Cunningham: Massage technique. No sedation.
6. Milch: Abduction and External Rotation (Hands over head).

Post-Reduction

• Check Neurovascular status.
• Check X-ray (confirm reduction).
• Sling (Broad arm) for 1-2 weeks (External Rotation sling theoretically better for Bankart healing, but poor compliance).

1. Arthroscopic Bankart Repair

• Indication: Soft tissue Bankart lesion. Minimal bone loss. First time dislocator in high-risk athlete (controversial) or Recurrent.
• Technique: Keyhole. Suture anchors reattach labrum to glenoid.

2. Latarjet Procedure (Coracoid Transfer)

• Indication: Bone Loss (>20% Glenoid or engaging Hill-Sachs). Contact athletes (Rugby). Failed Bankart repair.
• Mechanism: The Coracoid process (with Short Head of Biceps and Coracobrachialis attached) is cut and screwed onto the anterior glenoid.
• Triple Effect:
  1. Bone Block: Extends glenoid surface.
  2. Sling Effect: Conjoint tendon holds head back in abduction.
  3. Capsular Repair.
• Outcome: Very low recurrence (<1%). Gold standard for "Bony" instability.

3. Remplissage

• Indication: Large Hill-Sachs defect.
• Technique: Infraspinatus tendon is sutured into the Hill-Sachs defect to "fill" it and prevent it engaging.

The Recurrence Rule (Robinson et al.)

• Age is the single most important predictor.
• <20 years: 90% recurrence without surgery.
• >40 years: <10% recurrence.
• Implication: We offer early stabilisation to teenagers, but Conservative care to 30 year olds.

Latarjet vs Bankart (ISIS Score)

• The Instability Severity Index Score (ISIS) helps choose.
  • Points for: Age <20 (2), Competitive Sport (2), Contact Sport (1), Hyperlaxity (1), Hill Sachs (2), Glenoid Loss (2).
  • Score >6: Do Latarjet. Bankart will fail (50%).
  • Score <3: Bankart is acceptable.

What happened?

The ball of your arm bone popped out of the socket. We put it back in.

Will it happen again?

It depends on your age and anatomy.

• Teenagers: The ligaments are stretchy. It is very likely to pop out again (9 times out of 10). We might suggest keyhole surgery to tighten it.
• Adults (>40): It rarely comes out again because you get stiffer with age. However, you might have torn the rotator cuff muscle, which we need to check with an MRI.

Can I play rugby?

Not for 3-6 months. If you play sooner, it will dislocate. If you have surgery (Latarjet), you can return at 4-6 months with confidence.

Q1: What are the components of the "Triple Effect" of the Latarjet procedure? A: 1. Bony Effect: Increases glenoid diameter by attaching the coracoid. 2. Sling Effect: The Conjoint Tendon (Short Biceps/Coracobrachialis) acts as a hammock across the anterior joint when the arm is abducted/externally rotated. 3. Capsular Effect: The capsule is repaired to the CA ligament.

Q2: Describe the "Lightbulb Sign". A: Seen in Posterior Dislocation on the AP X-ray. The humeral head is locked in internal rotation, so the Greater Tuberosity profile is rotated anteriorly and hidden. The head appears perfectly round (like a lightbulb or ice cream cone) rather than its usual "walking stick" shape.

Q3: What is the "Engaging" Hill-Sachs lesion? A: A Hill-Sachs defect (dents in the back of the head) is "engaging" if its axis is parallel to the anterior glenoid rim in a functional position (Abduction/External Rotation). This means the head will drop into the defect and leverage itself out of the socket. It is a contraindication to isolated Bankart repair (needs Latarjet or Remplissage).

(End of Topic)