Shoulder Dislocation

Question 1

What is it?

Answer 1

> Disarticulation of humeral head with glenoid fossa

> Stability is provided by ligaments/labrum/rotator cuff and other muscles

Question 2

Anterior Dislocation - mechanism

Answer 2

> Most common
Apprehension position (abduction and lateral rotation which causes anterior glide of humeral head) combined with a blow creating antero-inferior displacement (main restraint = inferior g/h ligament)

Question 3

Anterior Dislocation - Associated injuries

Answer 3

> Hills-sachs lesion - small fracture/cortical depression in posterior humeral head (due to impact against rim of glenoid during displacement)
Bankart lesion - anterior damage to labrum (pulls away from rim)
Bony bankart = anterior glenoid fracture + labrum damage
Concurrent rotator cuff injuries
Neurovascular structures at risk (Brachial plexus and Axillary vessels)

Question 4

Posterior Dislocation

Answer 4

> 5% of cases 
> Causes: blow to front of shoulder
                : during seizures
> Often overlooked on x-ray 
> Occurs with 
- Concurrent Rotator Cuff injuries (particularly subscap)
- Posterior labrum injuries

Question 5

Recurrence

Answer 5

> 19.6% in 1st 2 years

> mostly in males and younger patients (almost 50% in 10-19 yr olds)

Question 6

Associated Injuries

Answer 6

> SLAP lesion (Sup. labrum AP)

• arm = forcefully bent inwards and twisted
• humeral head can tear labrum + long head of biceps from glenoid (front to back direction)
• presents similar to AC joint injury - SLAP = painful on eccentric biceps loading

> HAGL (humeral avulsion glenohumeral ligament)
- Capsule and inferior glenohumeral ligament are torn off humerus (high risk of recurrence of dislocation)

> ALPSA lesion (Ant. Labral Periosteal sleeve avulsion)

• Anterior labro-ligamentous complex rolls up in sleeve like fashion
• becomes displaced inferiorly and medially
• a.k.a medialised bankarts lesion