95% Anterior | Age Predicts Recurrence | Hill-Sachs and Bankart
- Anterior dislocation: Mechanism = abduction + external rotation (ABER); associated Bankart (anterior labrum) + Hill-Sachs (posterolateral head)
- Posterior dislocation: 50% MISSED on AP X-ray - look for lightbulb sign, get axillary lateral
- Age is the strongest predictor of recurrence: under 20 = 90%, over 40 = 25%
- First-time dislocation management is controversial: immobilization vs surgical stabilization in young athletes
- Axillary nerve at risk (around 30%) - test deltoid and regimental badge sensation
- “Posterior dislocation: seizure + internal rotation + empty antecubital fossa = posterior until proven otherwise
- “Engaging Hill-Sachs: lesion engages on Bankart defect during functional ROM - needs surgery
- “First-time dislocators under 25 in contact sports: consider early arthroscopic Bankart repair
- “Bone loss over 25% (glenoid) or over 40% (humeral) - may need Latarjet or bone grafting
50% of posterior dislocations are missed on initial presentation. AP X-ray may look normal. Lightbulb sign, rim sign, and loss of half-moon overlap are key. ALWAYS get axillary or Y-view.
Under 20 years: 90% recurrence. 20-40 years: 60% recurrence. Over 40 years: 25% recurrence but higher rotator cuff tear risk. Age guides surgical decision-making.
Axillary nerve injury in up to 30% of anterior dislocations. Test deltoid power and regimental badge sensation BEFORE and AFTER reduction. Document carefully.
Bankart lesion: Anterior labrum avulsion (67%). Hill-Sachs: Posterolateral humeral head impaction (40-90%). Bony Bankart: Associated bony fragment (5-10%).
- Presentation
- First anterior dislocation
- Treatment
- Consider early Bankart repair
- Key Pearl
- 90% recurrence if conservative
- Presentation
- First anterior dislocation
- Treatment
- Conservative, sling 2-4 weeks
- Key Pearl
- Activity modification, physio
- Presentation
- First anterior dislocation
- Treatment
- Conservative, early motion
- Key Pearl
- Check rotator cuff - high tear rate
- Presentation
- Posterior dislocation
- Treatment
- Urgent CT scan after reduction
- Key Pearl
- 50% missed on AP - always axillary view
- Presentation
- Recurrent instability
- Treatment
- Surgical stabilization
- Key Pearl
- Assess bone loss - Bankart vs Latarjet
ABERAnterior Dislocation Features
Hook:ABER position causes anterior dislocation - arm ABducted and Externally Rotated!
SEIZEPosterior Dislocation Causes
Hook:SEIZE the diagnosis - posterior dislocations occur during SEIZures and need Z-views!
LIGHTSX-ray Signs of Posterior Dislocation
Hook:If you see LIGHTS on the X-ray, think posterior dislocation - the 'lightbulb' is turned on!
AXILLARYNerve at Risk in Shoulder Dislocation
Hook:AXILLARY nerve - Always eXamine It, Look for Lateral deltoid, Always Record it, Yes document it!
Overview and Epidemiology
Shoulder dislocations are the most common major joint dislocation. Management has evolved significantly with evidence supporting early surgical stabilization in young athletes. The examiner will test your understanding of recurrence risk, associated lesions, and surgical indications.
- Bimodal distribution: young males (sports) and elderly (falls)
- Male:Female ratio: 2.5:1
- Peak incidence: 20-30 years
- Contact sports highest risk (AFL, rugby)
- Missing work/sport during recovery
- High recurrence rate in young patients
- Risk of progressive bone loss
- Potential career-ending for athletes
Anatomy and Mechanism
The glenohumeral joint sacrifices stability for mobility. The glenoid covers only 25-30% of the humeral head, relying on the labrum, capsule, and rotator cuff for stability. The labrum increases socket depth by 50% and contact area by 75%.
Static Stabilizers
- Function
- Deepens socket by 50%, bumper effect
- Injury Pattern
- Bankart lesion (anterior), Kim lesion (posterior)
- Function
- Primary restraint in ABER position
- Injury Pattern
- Torn in anterior dislocation
- Function
- Restraint in 45° abduction
- Injury Pattern
- Variable anatomy (absent in 30%)
- Function
- Resists inferior translation at rest
- Injury Pattern
- Less relevant to dislocation
- Function
- Resists external rotation at rest
- Injury Pattern
- Posterior dislocation injury
The Inferior Glenohumeral Ligament (IGHL) is the primary restraint to anterior dislocation in the ABER (Abduction External Rotation) position. It has anterior band, posterior band, and axillary pouch. The anterior band of IGHL is most critical for anterior stability.
Classification Systems
Classification by Direction of Dislocation
- Frequency
- 95%
- Mechanism
- ABER position - Abduction + External Rotation
- Key Features
- Bankart lesion + Hill-Sachs, axillary nerve at risk
- Frequency
- 3-4%
- Mechanism
- Seizure, electrocution, direct blow
- Key Features
- 50% missed on AP - lightbulb sign, fixed IR
- Frequency
- Less than 1%
- Mechanism
- Hyperabduction - arm locked overhead
- Key Features
- Highest nerve injury rate, rotator cuff tears
- Frequency
- Variable
- Mechanism
- Atraumatic instability, generalized laxity
- Key Features
- Requires different surgical approach
Anterior dislocations are subclassified by humeral head position: Subcoracoid (most common), Subglenoid, Subclavicular (rare), and Intrathoracic (very rare). All represent variations of anterior displacement with similar management principles.
Associated Lesions
Lesions with Anterior Dislocation
- Location
- Anterior labrum avulsion
- Incidence
- 67-97%
- Significance
- Essential lesion - repair for stability
- Location
- Posterolateral humeral head
- Incidence
- 40-90%
- Significance
- Engaging lesion needs addressing
- Location
- Anterior glenoid fracture
- Incidence
- 5-10%
- Significance
- Bone loss over 25% needs Latarjet
- Location
- Humeral avulsion of GHL
- Incidence
- 2-10%
- Significance
- Often missed, repair to humerus
- Location
- Anterior labrum periosteal sleeve avulsion
- Incidence
- Variable
- Significance
- Medially displaced labrum, heals poorly
- Location
- Supraspinatus usually
- Incidence
- Variable by age
- Significance
- Over 40 years: up to 40% incidence
An engaging Hill-Sachs lesion catches on the anterior glenoid rim during external rotation. The glenoid track concept helps determine if the Hill-Sachs is on-track (non-engaging) or off-track (engaging). Off-track lesions need additional surgery (remplissage or bone grafting).
Clinical Assessment
- Mechanism: ABER for anterior, seizure for posterior
- First or recurrent episode (recurrence is key!)
- Reduction: Self-reduced or ED reduction
- Sport/occupation: Contact sports, overhead work
- Hand dominance: Affects surgical decision
- Previous treatment: Physio, surgery, bracing
- Squared-off shoulder: Loss of deltoid contour
- Humeral head palpable anteriorly
- Empty glenoid posteriorly
- Arm held in slight abduction and ER
- Neurovascular: Axillary nerve (deltoid, regimental badge)
- Apprehension test positive after reduction
- Anterior
- Abducted, externally rotated
- Posterior
- Adducted, internally rotated (fixed)
- Anterior
- Palpable anteriorly
- Posterior
- Not palpable anteriorly (empty)
- Anterior
- Squared off, flattened
- Posterior
- Flattened anteriorly, fullness posteriorly
- Anterior
- Unable to internally rotate
- Posterior
- Unable to externally rotate (locked)
- Anterior
- Rarely missed
- Posterior
- Missed 50% of time!
50% of posterior dislocations are missed on initial presentation. Key clinical clues: arm fixed in internal rotation, cannot externally rotate, empty antecubital fossa (head not palpable anteriorly), and history of seizure or electrocution.
- Distinguishing Features
- Squared-off contour, arm in abduction/ER, head palpable anteriorly
- Key Investigation
- AP plus axillary/Y-view radiograph
- Distinguishing Features
- Arm locked in IR, cannot ER, post-seizure or shock
- Key Investigation
- Axillary lateral - lightbulb/trough sign; CT
- Distinguishing Features
- Bony crepitus, diffuse bruising, often older patient
- Key Investigation
- Trauma series radiograph; CT if comminuted
- Distinguishing Features
- Cannot actively abduct but joint located, passive ROM preserved
- Key Investigation
- Ultrasound or MRI; relevant especially over 40
- Distinguishing Features
- Tenderness/step over ACJ, deformity lateral not glenohumeral
- Key Investigation
- AP and Zanca views
- Distinguishing Features
- Fever, raised inflammatory markers, no clear injury
- Key Investigation
- Joint aspiration, CRP/WCC
The topic mentions the apprehension test in passing, but the clinical examination for instability (for the located, recurrently-unstable shoulder) is a classic OSCE station - know the full battery and what each test means.
- Apprehension test: arm abducted to 90 degrees with progressive external rotation (ABER) - a positive test is the apprehension/fear that it will dislocate (not pain), reproducing the unstable position.
- Relocation (Jobe) test: from the apprehensive position, a posteriorly directed force on the proximal humerus relieves the apprehension - confirms anterior instability.
- Surprise (release) test: suddenly releasing that posterior force returns the apprehension - the most specific sign of anterior instability.
- Load-and-shift: axially load the head into the glenoid then translate it anteriorly and posteriorly, grading translation - assesses the direction and amount of laxity.
- Sulcus sign: with the arm at the side, downward traction produces a dimple below the acromion - inferior laxity; if it persists in external rotation it suggests a rotator-interval lesion, and it is a hallmark of multidirectional instability/generalised laxity.
- Gagey hyperabduction test: passive glenohumeral abduction beyond about 105 degrees (compared with the other side) indicates inferior glenohumeral ligament laxity.
- Jerk test / Kim test: an axial load on the flexed, adducted, internally rotated arm (moved into abduction for the jerk test) produces a clunk with a posterior labral lesion.
Also screen generalised ligamentous laxity (Beighton score), which points toward atraumatic/multidirectional instability.
Exam point: for anterior instability the sequence is apprehension -> relocation -> surprise (most specific); use load-and-shift to grade laxity, the sulcus sign and Gagey test for inferior/multidirectional laxity, the jerk/Kim test for posterior instability, and the Beighton score for generalised laxity.
Investigations
Imaging Protocol
AP (true AP in scapular plane), Axillary lateral, and Scapular Y view. NEVER rely on AP alone - must get axillary or Y-view to exclude posterior dislocation.
Shows head position relative to glenoid. If patient cannot abduct (Velpeau view alternative - arm across chest, lean back for axillary).
Confirm reduction with repeat trauma series. Document any fractures visible post-reduction.
MRI: Best for labrum (Bankart), capsule, rotator cuff. CT: Best for bone loss quantification (glenoid and humeral).
X-ray Signs of Posterior Dislocation
Humeral head appears round like a lightbulb on AP due to internal rotation. Loss of normal head contour.
Increased distance between medial head and anterior glenoid rim (over 6mm). Joint space widening.
Vertical sclerotic line on medial humeral head = reverse Hill-Sachs impaction fracture visible en face.
Normal overlap of humeral head on glenoid rim is lost when head displaces posteriorly.
Management Algorithm
Before reduction: (1) Document neurovascular status (axillary nerve!), (2) Confirm diagnosis with X-ray, (3) Obtain consent, (4) Ensure adequate analgesia/sedation, (5) Have post-reduction X-ray plan.
Reduction Techniques - Anterior Dislocation
Reduction Methods
Patient prone, arm hanging off table. Attach 2-5kg weight. Gentle internal/external rotation. Uses gravity and muscle fatigue. Least force.
Patient supine, elbow at 90°. Slow external rotation while adducting arm. Gentle, low force, minimal sedation.
Patient seated, massage biceps, deltoid, and trapezius to relax. Patient leans forward. No traction - muscle relaxation only.
Traction-countertraction methods. Higher force, historical. Kocher has fracture risk - avoid.
- Repeat neurovascular exam (document!)
- Post-reduction X-rays (confirm reduction)
- Immobilize in sling
- Provide analgesia
- Arrange follow-up and MRI
- Interposed tissue (rotator cuff, biceps)
- Associated fracture blocking
- Inadequate anesthesia
- May need open reduction
- Posterior dislocations often harder
The classification section lists AMBRI and Stanmore Pole II, but multidirectional instability is a distinct entity managed completely differently from the traumatic Bankart shoulder - and a favourite exam trap.
- What it is: symptomatic instability in two or more directions (usually inferior plus anterior or posterior), typically atraumatic or from repetitive microtrauma, in patients with generalised ligamentous laxity (high Beighton score) - classically swimmers, throwers, gymnasts. The mnemonic is AMBRI (Atraumatic, Multidirectional, Bilateral, Rehabilitation, Inferior capsular shift).
- The hallmark sign is a positive sulcus sign (inferior laxity), often bilateral, with no discrete Bankart or bony lesion - the problem is a redundant, capacious capsule, not bone loss.
- First-line is prolonged, structured rehabilitation (the Rockwood-type programme): rotator-cuff and scapular-stabiliser dynamic strengthening and proprioception - the majority improve and avoid surgery; address any muscle-patterning/voluntary component (Stanmore Pole III) with biofeedback/psychology rather than an operation.
- Surgery only after a genuine failed rehabilitation trial (6 months or more): an inferior capsular shift (Neer) or capsular plication (open or arthroscopic) that reduces capsular volume in all directions, often with rotator-interval closure.
- Critical trap: bony procedures (Latarjet / bone block) are WRONG for atraumatic MDI - there is no bone loss to replace, and over-constraint risks stiffness and arthropathy. Reserve bone block for traumatic instability with true bone loss.
Exam point: MDI is an atraumatic, generalised-laxity, sulcus-sign-positive, capsular-redundancy problem - treat with prolonged dynamic-stabiliser rehabilitation first, then capsular shift/plication with rotator-interval closure if it fails; never use a Latarjet/bone block for atraumatic MDI.
Surgical Technique
Arthroscopic Bankart Repair
Operative Steps
Beach chair or lateral decubitus with arm in traction. Author preference varies. Beach chair = easier orientation, lateral = better inferior access.
Posterior viewing portal (soft spot), anterior working portal (rotator interval), anteroinferior accessory portal for anchor placement.
Elevate labrum off glenoid neck with elevator. Mobilize until subscapularis seen medially. Fresh bleeding edge essential.
Rasp glenoid rim to create bleeding bone bed. Do not over-decorticate (bone loss).
3-4 suture anchors from 5 o'clock to 3 o'clock (right shoulder). Inferior anchors most important - capture IGHL.
Pass sutures through labrum, tie sequentially. Goal: bumper effect restoration, recreate labral height on glenoid rim.
- Inferior anchor first (most important)
- Labral shift superiorly - recreate tension
- On glenoid face, not edge (prevents erosion)
- 3-4 anchors standard (more if SLAP)
- Check reduction with probe
- Inadequate mobilization - labrum stays medial
- Anchors placed too laterally - poor healing
- Missing inferior extent - recurrence
- Not addressing Hill-Sachs if engaging
- Missing HAGL lesion - lateral capsule
Complications
- Incidence
- 10-15% after Bankart
- Risk Factors
- Young age, contact sport, bone loss, poor tissue
- Management
- Revision surgery, consider Latarjet
- Incidence
- Up to 30% initial
- Risk Factors
- Inferior dislocation, elderly, delayed reduction
- Management
- Most recover 3-6 months, EMG at 3 months
- Incidence
- Over 40 years: 40%
- Risk Factors
- Age over 40, high-energy, recurrent
- Management
- MRI assessment, repair if symptomatic
- Incidence
- 5-10%
- Risk Factors
- Prolonged immobilization, elderly
- Management
- Early motion, physiotherapy
- Incidence
- 10-20% long-term
- Risk Factors
- Recurrent dislocations, bone loss
- Management
- Activity modification, arthroplasty if severe
- Incidence
- Rare
- Risk Factors
- High-energy, elderly (axillary artery)
- Management
- Urgent vascular surgery consultation
90% of axillary nerve injuries recover within 3-6 months. If no clinical recovery by 3 months, obtain EMG/NCS. Consider nerve exploration if no recovery by 6-9 months.
Postoperative Care and Rehabilitation
Rehabilitation After Bankart Repair
Sling full-time. Pendulum exercises only. Ice and analgesia. No external rotation.
Sling when out. Active elbow and hand. Passive forward flexion, ER to neutral only. No combined ABD+ER.
Wean sling. AROM all directions. Isometric then isotonic strengthening. Rotator cuff and scapular stabilizers.
Full ROM. Progressive resistance. Sport-specific drills. No contact until 6 months.
Full strength and ROM. Functional testing. Return to contact sport 6 months minimum.
Internal vs External rotation immobilization: Some studies suggested ER immobilization reduces recurrence (Itoi) by approximating Bankart lesion to glenoid. However, meta-analyses show no significant difference. Practical: IR sling is easier and standard.
Outcomes and Prognosis
- Better Outcome
- Older (over 30)
- Worse Outcome
- Younger (under 20)
- Better Outcome
- Single episode
- Worse Outcome
- Multiple recurrences
- Better Outcome
- Minimal (under 15%)
- Worse Outcome
- Significant (over 25%)
- Better Outcome
- Non-contact
- Worse Outcome
- Contact/collision sports
- Better Outcome
- Good labral tissue
- Worse Outcome
- Attenuated/ALPSA pattern
Guidelines, Registries & Global Practice
- Most common large-joint dislocation worldwide; anterior accounts for around 95%
- Population incidence roughly 15-25 per 100,000 person-years
- Strongly bimodal: young males (contact sport - rugby, American/Australian football, handball) and older patients (low-energy falls)
- Age at first dislocation is the dominant recurrence driver across all populations
- Latarjet and bony procedures captured in shoulder-instability registries (e.g. Nordic and national arthroplasty/instability datasets) show low recurrence but a measurable reoperation/complication burden
- High-resource settings: early MRI/CT bone-loss assessment and arthroscopic stabilization are common
- Limited-resource settings: closed reduction with sling and selective referral predominate; CT/MRI access may be rationed
- Region
- United States
- Emphasis
- Shared decision-making for first-time dislocation; image-guided assessment of bone loss before surgical planning
- Region
- United Kingdom
- Emphasis
- Structured pathway: reduction, axillary nerve documentation, early specialist review for young/recurrent instability
- Region
- Global (trauma)
- Emphasis
- Reduction technique, post-reduction imaging, and recognition of associated fractures (greater tuberosity, glenoid rim)
- Region
- Europe
- Emphasis
- Risk stratification (ISIS, glenoid track) to select Bankart vs bone-block procedures
The largest area of legitimate variation is the threshold for primary stabilization of a first-time dislocation. North American sports-medicine practice leans toward early arthroscopic stabilization for young contact athletes, whereas several European and trauma-oriented pathways favour an initial non-operative trial with stabilization reserved for recurrence or demonstrable bone loss. Both are defensible - the deciding factors are age, sport demand, and quantified bone loss, not geography.
Key documentation: (1) Pre-reduction neurovascular exam (axillary nerve), (2) Consent for reduction including risks, (3) Post-reduction neurovascular exam, (4) Imaging before and after, (5) Counseling about recurrence risk and treatment options. Failure to obtain axillary view leading to missed posterior dislocation is a recognized litigation risk.
Controversies and Areas of Uncertainty
RCT evidence (Kirkley, Jakobsen) shows early stabilization cuts recurrence, but Hovelius shows many young dislocators stabilize without surgery. The genuine debate is patient selection, not whether surgery works.
The classic 25% glenoid bone-loss cut-off is being challenged by subcritical bone loss (around 13.5-20%) data suggesting Bankart alone may underperform earlier than thought, especially in contact athletes.
For off-track Hill-Sachs with subcritical glenoid loss, Bankart plus remplissage and Latarjet give comparable recurrence, with fewer complications reported for remplissage - optimal choice remains unsettled.
External-rotation bracing (Itoi) theoretically reapproximates the Bankart lesion, but pooled data (Paterson) show only a non-significant trend; most units default to a short period in a standard internal-rotation sling.
MCQ Practice Points
Q: Which ligament is the primary restraint to anterior dislocation in the ABER position? A: Anterior band of the Inferior Glenohumeral Ligament (IGHL). The IGHL is taut in abduction and external rotation and is torn in anterior dislocation, leading to Bankart lesion.
Q: What percentage of posterior shoulder dislocations are missed on initial presentation? A: Up to 50%. AP X-ray may appear normal. Key is to recognize clinical signs (arm fixed in IR, cannot ER) and obtain axillary lateral view. Lightbulb sign, rim sign, and lost half-moon are X-ray clues.
Q: What is the recurrence rate for first-time anterior dislocation in patients under 20 years treated conservatively? A: Up to 90%. Age is the strongest predictor of recurrence. This high rate supports early surgical stabilization in young athletes.
Q: At what percentage of glenoid bone loss does arthroscopic Bankart repair have unacceptable failure rates? A: Over 25% (some say 20%). At this threshold, isolated Bankart repair fails in 67% of cases. Latarjet procedure is indicated for significant glenoid bone loss.
Q: Which nerve is most commonly injured in anterior shoulder dislocation, and how is it tested? A: Axillary nerve (up to 30%). Test deltoid power (abduction) and sensation over the regimental badge area (lateral deltoid). Document pre and post-reduction.
Q: What is an engaging Hill-Sachs lesion? A: A Hill-Sachs defect that engages on the anterior glenoid rim during functional external rotation - the lesion is 'off-track' based on the glenoid track concept. Requires additional surgery (remplissage or bone grafting) beyond Bankart repair.
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 19-year-old AFL footballer presents to ED with left shoulder pain after a tackle. He felt his shoulder 'pop out' and it was reduced on the field by the team physio. X-rays show a reduced glenohumeral joint. He is keen to return to football as soon as possible. How would you manage him?”
“A 45-year-old man presents 3 weeks after a seizure with persistent shoulder pain. He was seen in ED on the day of seizure, had an AP X-ray 'reported as normal' and was discharged. He cannot externally rotate his shoulder. Examination shows the arm fixed in internal rotation. What is your assessment?”
“A 28-year-old rugby player has had 5 anterior shoulder dislocations over 3 years and has apprehension with his arm in throwing position. He had an arthroscopic Bankart repair 2 years ago which 'worked for 6 months' before he started dislocating again. MRI shows attenuated anterior labrum. CT shows 28% glenoid bone loss. What surgical options would you discuss?”
Key Anatomy
- IGHL anterior band = primary restraint in ABER
- Labrum increases socket depth by 50%
- Axillary nerve = most at risk (30%)
- Regimental badge sensation = axillary nerve test
Classification
- Anterior: 95% - ABER mechanism, Bankart + Hill-Sachs
- Posterior: 3-4% - seizure/electrocution, lightbulb sign
- Inferior (luxatio erecta): rare, arm locked overhead
- ALWAYS get axillary view - posterior missed 50%
Associated Lesions
- Bankart: anterior labrum avulsion (67%)
- Hill-Sachs: posterolateral head impaction (40-90%)
- HAGL: humeral avulsion of GHL (missed on scope)
- Bone loss over 25% = cannot do Bankart alone
Recurrence by Age
- Under 20 years: 90% recurrence
- 20-40 years: 40-60% recurrence
- Over 40 years: under 25% (but check cuff!)
- Early stabilization reduces recurrence in young
Surgical Options
- Bankart repair: standard, 10-15% recurrence
- Latarjet: bone loss over 25%, 3-5% recurrence
- Remplissage: engaging Hill-Sachs (off-track)
- Return to contact sport: 6 months minimum
Evidence Base and Key Trials
Surgery vs Conservative for First-Time Dislocation
Kirkley et al. - Immediate Arthroscopic Stabilization RCT (Long-Term)
- RCT of 40 patients under 30 with a first traumatic anterior dislocation
- Immediate arthroscopic stabilization vs immobilization plus rehabilitation
- At mean 75 months, significantly lower redislocation rate with surgery (original 2-year data: 15.9% surgery vs 47% conservative)
- Small but clinically significant WOSI advantage; no ASES/DASH difference
Jakobsen et al. - Primary Repair vs Conservative, 10-Year Follow-Up
- RCT of 76 patients aged 15-39 (37 open repair vs 39 conservative)
- At 2 years recurrence was 3% after open repair vs 56% conservative (p less than 0.005)
- At 10 years (Oxford score) 72% good/excellent after surgery vs 75% unsatisfactory conservative
- More positive apprehension among non-dislocators in the conservative group (39% vs 7%)