Shoulder Instability

Acute dislocation - history:

• •Traumatic mechanism: forced abduction and external rotation (anterior); seizure, electrocution, or direct posterior force (posterior)
• •Sudden severe pain, inability to move shoulder
• •Arm position: anterior - slight abduction and external rotation; posterior - adducted and internally rotated, cannot externally rotate

Acute dislocation - examination:

• •Loss of normal deltoid contour
• •Neurovascular assessment mandatory before AND after reduction; axillary nerve (regimental badge sensation, deltoid contraction) is most commonly affected, with clinical injury in roughly 1 in 7 dislocations
• •Vascular: radial pulse, capillary refill

Recurrent instability - examination tests:

• •Apprehension test: 90° abduction with external rotation; patient becomes apprehensive. Most important test for anterior instability
• •Relocation (Jobe) test: posterior force on the humeral head during apprehension position relieves apprehension
• •Surprise / release test: removing the posterior force returns apprehension. Most specific test
• •Sulcus sign: downward traction shows inferior sulcus beneath the acromion (graded 1-3)
• •Beighton score: screen for generalised hypermobility
• •Assess rotator cuff strength, particularly in patients over 40

Red flags to exclude:

• •Neurovascular deficit post-dislocation - document and act urgently
• •Associated fracture - X-ray before AND after reduction
• •Posterior dislocation missed on AP X-ray - if external rotation is blocked after a normal AP, get an axillary view
• •Unreduced dislocation presenting late

Acute dislocation:

• •Plain radiographs (AP obligatory; axillary view preferred): mandatory before AND after reduction. Confirm direction, exclude fracture, confirm concentric reduction, identify Hill-Sachs or bony Bankart.
• •Post-reduction neurovascular assessment: document axillary nerve function explicitly.
• •In patients over 40: arrange early imaging (USS or MRI) to assess rotator cuff integrity per NICE CKS and BESS.

Recurrent instability - specialist pathway:

• •MR arthrogram: investigation of choice for labral pathology (Bankart, ALPSA, HAGL, GLAD).
• •CT with 3D reconstruction: standard for quantifying glenoid bone loss. Approximately 20% bone loss is the threshold where isolated soft tissue repair becomes less reliable (BESS).
• •Standard MRI: adequate for rotator cuff assessment but less sensitive than MR arthrogram for labral pathology.

Acute first-time dislocation:

• •Reduction: prompt closed reduction under analgesia or sedation. Neurovascular assessment before and after. Post-reduction X-ray. Gentler techniques (Spaso, Stimson) preferred over Kocher / Hippocratic - lower rates of iatrogenic brachial plexus injury and humeral shaft fracture
• •Immobilisation: sling for comfort short-term, then early mobilisation. Prolonged immobilisation does not reduce recurrence (BESS). External rotation bracing not routinely recommended
• •Analgesia: paracetamol, short-course oral NSAIDs
• •Early rehabilitation: gentle ROM, then rotator cuff and periscapular strengthening
• •Patients over 40: early imaging for cuff integrity

Age-based pathway after first anterior dislocation:

• •Under 25: highest recurrence risk - consider early specialist review for shared decision-making
• •25-40: reassess at 3-6 months per NICE CKS
• •Over 40: cuff integrity is the priority

Atraumatic instability - per BESS pathway (2019):

• •Rehabilitation is first-line; do NOT image in primary care; do NOT use glucocorticoid injections; surgery only after a minimum of 6 months of structured supervised physiotherapy with good compliance
• •Symptoms may take up to 6 months to improve; refer for specialist assessment if structured rehabilitation fails after that period

Surgical options (awareness):

• •Arthroscopic Bankart repair: standard for recurrent anterior instability with Bankart lesion and minimal bone loss
• •Latarjet procedure: for significant glenoid bone loss (~20% per BESS), engaging Hill-Sachs, or failed Bankart repair
• •Remplissage: infraspinatus tenodesis into Hill-Sachs defect, used with Bankart repair for engaging Hill-Sachs lesions

Post-acute dislocation:

• •Phase 1: sling for comfort, gentle pendular exercises, isometric cuff activation
• •Phase 2: wean from sling, active-assisted then active ROM, isotonic cuff strengthening, scapular stabilisation
• •Phase 3: progressive resistance, dynamic stabilisation, proprioceptive training, sport-specific drills
• •Phase 4: return to contact sport when strength is symmetrical and confidence restored, typically 3-6 months

Atraumatic instability:

• •Rotator cuff and periscapular strengthening for dynamic stability
• •Proprioceptive training is particularly important
• •Avoid stretching programmes - these worsen laxity
• •Symptoms may take up to 6 months to improve

Post-operative (awareness): sling 3-6 weeks, limited external rotation initially, progressive ROM, strengthening from 6-12 weeks, return to contact sport typically 6-9 months.

• •BESS Atraumatic Shoulder Instability Pathway (2019) - Rehabilitation first-line, no imaging or injections in primary care, refer at 6 months if structured rehab fails.
• •NICE CKS: Shoulder instability - Reduction-then-rehabilitation pathway with age-based stratification; over-40s prioritise cuff integrity, under-25s consider early specialist review.
• •Stanmore Polar Triangle classification (Bayley) - Adds Type III (muscle patterning) to TUBS / AMBRI; surgery on Type III is contraindicated.
• •Glenoid bone loss threshold - Approximately 20% bone loss is the BESS threshold where isolated Bankart repair becomes less reliable, prompting consideration of Latarjet.
• •Reduction technique - Spaso and Stimson are preferred over Kocher / Hippocratic to reduce iatrogenic brachial plexus injury and humeral shaft fracture risk.

• •Apprehension - relocation - surprise/release is the test sequence for anterior instability. Apprehension is most important; surprise/release is the most specific test.
• •Spaso and Stimson reduction techniques are preferred over Kocher / Hippocratic - lower rates of iatrogenic brachial plexus injury and humeral shaft fracture.
• •Axillary nerve injury is the commonest neurological complication - check regimental badge sensation and deltoid contraction before AND after reduction.
• •Atraumatic instability per BESS: do NOT image in primary care, do NOT inject, do NOT rush to surgery - structured rehabilitation for at least 6 months.
• •Parsonage-Turner syndrome (brachial neuritis) is a classic mimic - sudden burning shoulder pain followed by multimyotomal weakness, no trauma, often post-viral.