High Yield Overview

SHOULDER DISLOCATIONS - ANTERIOR VS POSTERIOR

95% Anterior | Age Predicts Recurrence | Hill-Sachs and Bankart

95%Anterior dislocations

90%Recurrence if under 20

25%Recurrence if over 40

67%Bankart lesion rate

DIRECTION OF DISLOCATION

Pattern95% - arm abducted, externally rotated

TreatmentClosed reduction, assess stability

Posterior

Pattern3-4% - seizure, electrocution, FOOSH

TreatmentClosed reduction, CT scan

Inferior (Luxatio Erecta)

PatternRare - arm fixed overhead

TreatmentClosed reduction, check axillary nerve

Critical Must-Knows

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

Examiner's Pearls

"
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

Clinical Imaging

Imaging Gallery

2-panel AP shoulder X-rays showing bilateral anterior glenohumeral dislocations - humeral heads displaced medially and inferiorly below the coracoid process. Timestamps visible (14 12:51). — 2-panel AP shoulder X-rays showing bilateral anterior glenohumeral dislocations - humeral heads displaced medially and inferiorly below the coracoid pCredit: Dlimi F et al. - J Orthop Traumatol via Open-i (NIH) - PMC3284668 (CC-BY 4.0)

2-panel (A-B) AP shoulder X-rays from motor vehicle accident: (A) right shoulder with anterior dislocation and glenoid rim fracture (white arrows/arrowheads), (B) left shoulder showing similar anterio — 2-panel (A-B) AP shoulder X-rays from motor vehicle accident: (A) right shoulder with anterior dislocation and glenoid rim fracture (white arrows/arroCredit: Abu-Zidan FM et al. - Saudi Med J via Open-i (NIH) - PMC4707410 (CC-BY 4.0)

Single AP chest X-ray demonstrating bilateral anterior shoulder dislocations - both humeral heads displaced inferiorly and medially with empty glenoid fossae visible. — Single AP chest X-ray demonstrating bilateral anterior shoulder dislocations - both humeral heads displaced inferiorly and medially with empty glenoidCredit: Silva LP et al. - Rev Bras Ortop via Open-i (NIH) - PMC4799227 (CC-BY 4.0)

2-panel (a-b) AP shoulder X-rays showing pre- and post-reduction: (a) anterior dislocation with humeral head displaced under coracoid, (b) successful closed reduction with humeral head relocated into — 2-panel (a-b) AP shoulder X-rays showing pre- and post-reduction: (a) anterior dislocation with humeral head displaced under coracoid, (b) successful Credit: Takase F et al. - Case Rep Orthop via Open-i (NIH) - PMC4082929 (CC-BY 4.0)

Hill-Sachs deformity on AP shoulder radiograph — AP shoulder radiograph demonstrating a Hill-Sachs lesion - the characteristic posterolateral humeral head impaction fracture resulting from anterior shoulder dislocation. The defect is created when the soft posterolateral head impacts against the hard anterior glenoid rim during dislocation.Credit: PMC - CC BY 4.0

Critical Shoulder Dislocation Exam Points

Do NOT Miss Posterior!

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.

Age = Recurrence

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

Axillary nerve injury in up to 30% of anterior dislocations. Test deltoid power and regimental badge sensation BEFORE and AFTER reduction. Document carefully.

Associated Lesions

Bankart lesion: Anterior labrum avulsion (67%). Hill-Sachs: Posterolateral humeral head impaction (40-90%). Bony Bankart: Associated bony fragment (5-10%).

Quick Decision Guide

Patient	Presentation	Treatment	Key Pearl
Young athlete under 20	First anterior dislocation	Consider early Bankart repair	90% recurrence if conservative
Adult 30-50 years	First anterior dislocation	Conservative, sling 2-4 weeks	Activity modification, physio
Elderly over 60	First anterior dislocation	Conservative, early motion	Check rotator cuff - high tear rate
Any age	Posterior dislocation	Urgent CT scan after reduction	50% missed on AP - always axillary view
Any age	Recurrent instability	Surgical stabilization	Assess bone loss - Bankart vs Latarjet

Mnemonic

ABERAnterior Dislocation Features

Abduction

Arm abducted during injury

Bankart lesion

Anterior labrum avulsion

External rotation

Mechanism of injury

Rotator interval stretched

Anterior capsular damage

Memory Hook:ABER position causes anterior dislocation - arm ABducted and Externally Rotated!

Mnemonic

SEIZEPosterior Dislocation Causes

Seizure

Most common cause - internal rotators overpower

Electrocution

Massive muscle contraction

Internal rotation fixed

Clinical sign - arm held in IR

Z-view needed

Y-view or axillary to diagnose

Empty antecubital fossa

Head not palpable anteriorly

Memory Hook:SEIZE the diagnosis - posterior dislocations occur during SEIZures and need Z-views!

Mnemonic

LIGHTSX-ray Signs of Posterior Dislocation

Lightbulb sign

Head looks like lightbulb in internal rotation

Internal rotation locked

Arm fixed in IR

Gross widening of joint space

Over 6mm joint space

Half-moon overlap lost

Normal glenoid-head overlap absent

Trough sign

Reverse Hill-Sachs on AP view

Scapular Y confirms

Head posterior to glenoid

Memory Hook:If you see LIGHTS on the X-ray, think posterior dislocation - the 'lightbulb' is turned on!

Mnemonic

AXILLARYNerve at Risk in Shoulder Dislocation

Axillary nerve

Most commonly injured (30%)

X-ray before and after

Document reduction

Inferior capsule proximity

Nerve runs just below capsule

Lateral deltoid weakness

Test abduction

Loss of sensation

Regimental badge area

Always document

Pre and post reduction

Recovery expected

90% recover by 6 months

You must test it

Medicolegal requirement

Memory Hook:AXILLARY nerve - Always eXamine It, Look for Lateral deltoid, Always Record it, Yes document it!

Overview and Epidemiology

Why This Topic Matters

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.

Demographics

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)

Impact

Missing work/sport during recovery
High recurrence rate in young patients
Risk of progressive bone loss
Potential career-ending for athletes

Anatomy and Mechanism

Key Anatomical Concept

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

Structure	Function	Injury Pattern
Glenoid labrum	Deepens socket by 50%, bumper effect	Bankart lesion (anterior), Kim lesion (posterior)
IGHL (Inferior Glenohumeral Ligament)	Primary restraint in ABER position	Torn in anterior dislocation
MGHL (Middle GHL)	Restraint in 45° abduction	Variable anatomy (absent in 30%)
SGHL (Superior GHL)	Resists inferior translation at rest	Less relevant to dislocation
Coracohumeral ligament	Resists external rotation at rest	Posterior dislocation injury

IGHL Anatomy

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

Type	Frequency	Mechanism	Key Features
Anterior (Subcoracoid)	95%	ABER position - Abduction + External Rotation	Bankart lesion + Hill-Sachs, axillary nerve at risk
Posterior	3-4%	Seizure, electrocution, direct blow	50% missed on AP - lightbulb sign, fixed IR
Inferior (Luxatio Erecta)	Less than 1%	Hyperabduction - arm locked overhead	Highest nerve injury rate, rotator cuff tears
Multidirectional	Variable	Atraumatic instability, generalized laxity	Requires different surgical approach

Anterior Subclassification

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

Lesion	Location	Incidence	Significance
Bankart lesion	Anterior labrum avulsion	67-97%	Essential lesion - repair for stability
Hill-Sachs lesion	Posterolateral humeral head	40-90%	Engaging lesion needs addressing
Bony Bankart	Anterior glenoid fracture	5-10%	Bone loss over 25% needs Latarjet
HAGL lesion	Humeral avulsion of GHL	2-10%	Often missed, repair to humerus
ALPSA lesion	Anterior labrum periosteal sleeve avulsion	Variable	Medially displaced labrum, heals poorly
Rotator cuff tear	Supraspinatus usually	Variable by age	Over 40 years: up to 40% incidence

Hill-Sachs and Bone Loss

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).

Arthroscopic remplissage procedure for engaging Hill-Sachs lesion — Arthroscopic remplissage technique for engaging Hill-Sachs lesion: (A,B) fluoroscopic images showing suture anchor placement into the Hill-Sachs defect with posterior capsule and infraspinatus tendon captured to fill the bony defect, preventing engagement on the anterior glenoid rim.Credit: PMC - CC BY 4.0

Clinical Assessment

History

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

Examination - Anterior

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 vs Posterior Clinical Signs

Finding	Anterior	Posterior
Arm position	Abducted, externally rotated	Adducted, internally rotated (fixed)
Humeral head	Palpable anteriorly	Not palpable anteriorly (empty)
Shoulder contour	Squared off, flattened	Flattened anteriorly, fullness posteriorly
Movement	Unable to internally rotate	Unable to externally rotate (locked)
Common miss	Rarely missed	Missed 50% of time!

Posterior Dislocation - Don't Miss It!

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.

Clinical photograph of bilateral anterior shoulder dislocations — Clinical examination of bilateral anterior shoulder dislocations: The characteristic 'squared-off' shoulder appearance is visible bilaterally, caused by loss of the normal rounded deltoid contour when the humeral heads are displaced anteriorly from the glenoid fossae. This clinical sign, combined with palpable humeral head anteriorly and empty glenoid posteriorly, is pathognomonic for anterior dislocation.Credit: Dlimi F et al., J Orthop Traumatol - CC BY 4.0

Investigations

Imaging Protocol

First LinePlain Radiographs - Trauma Series

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.

If Posterior SuspectedAxillary Lateral (Essential)

Shows head position relative to glenoid. If patient cannot abduct (Velpeau view alternative - arm across chest, lean back for axillary).

Post-ReductionRepeat X-rays

Confirm reduction with repeat trauma series. Document any fractures visible post-reduction.

Definitive AssessmentMRI or CT

MRI: Best for labrum (Bankart), capsule, rotator cuff. CT: Best for bone loss quantification (glenoid and humeral).

Bilateral anterior shoulder dislocations on X-ray — Two-panel AP shoulder X-rays demonstrating bilateral anterior glenohumeral dislocations: both humeral heads are displaced inferomedially under the coracoid process with empty glenoid fossae. Bilateral dislocations are rare and typically result from high-energy trauma or seizures. Classic anterior dislocation position = head inferior to coracoid with loss of normal acromiohumeral relationship.Credit: Dlimi F et al., J Orthop Traumatol - CC BY 4.0

Bilateral anterior shoulder dislocations with associated glenoid fractures — Two-panel AP shoulder radiographs from motor vehicle accident: (A) Right shoulder with anterior dislocation and associated glenoid rim fracture (white arrows and arrowheads indicating fracture fragments), (B) Left shoulder showing similar anterior dislocation pattern. Associated bony Bankart lesions (glenoid rim fractures) occur in 5-10% of anterior dislocations and affect surgical decision-making.Credit: Abu-Zidan FM et al., Saudi Med J - CC BY 4.0

AP chest X-ray showing bilateral anterior shoulder dislocations — Single AP chest radiograph demonstrating bilateral anterior shoulder dislocations: both humeral heads are displaced inferiorly and medially with empty glenoid fossae visible. This overview image shows the typical inferomedial position of the humeral heads in anterior dislocations. Simultaneous bilateral dislocations are rare, usually resulting from high-energy trauma, seizures, or electrocution.Credit: Silva LP et al., Rev Bras Ortop - CC BY 4.0

X-ray Signs of Posterior Dislocation

Posterior shoulder dislocation with lightbulb sign and CT confirmation — Posterior shoulder dislocation imaging: (A) AP radiograph demonstrating the 'lightbulb sign' - internally rotated humeral head appearing round, (B) Axillary/Y-view confirming posterior head displacement, (C) Axial CT showing posterior dislocation with reverse Hill-Sachs (McLaughlin) lesion on the anteromedial humeral head.Credit: PMC - CC BY 4.0

Posterior shoulder dislocation X-ray teaching comparison — AP radiograph comparison demonstrating subtle signs of posterior dislocation: asterisk indicates the abnormal glenoid-humeral relationship (rim sign), arrow shows the trough line representing reverse Hill-Sachs defect. These subtle findings are frequently missed - 50% of posterior dislocations are missed on initial presentation.Credit: PMC - CC BY 4.0

Lightbulb Sign

Humeral head appears round like a lightbulb on AP due to internal rotation. Loss of normal head contour.

Rim Sign

Increased distance between medial head and anterior glenoid rim (over 6mm). Joint space widening.

Trough Sign

Vertical sclerotic line on medial humeral head = reverse Hill-Sachs impaction fracture visible en face.

Lost Half-Moon

Normal overlap of humeral head on glenoid rim is lost when head displaces posteriorly.

Management Algorithm

Pre-Reduction Checklist

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

PreferredStimson Technique

Patient prone, arm hanging off table. Attach 2-5kg weight. Gentle internal/external rotation. Uses gravity and muscle fatigue. Least force.

AlternativeExternal Rotation Method

Patient supine, elbow at 90°. Slow external rotation while adducting arm. Gentle, low force, minimal sedation.

No TractionCunningham Technique

Patient seated, massage biceps, deltoid, and trapezius to relax. Patient leans forward. No traction - muscle relaxation only.

HistoricalHippocratic/Kocher

Traction-countertraction methods. Higher force, historical. Kocher has fracture risk - avoid.

Anterior shoulder dislocation pre and post reduction comparison — Two-panel (a-b) AP shoulder X-rays demonstrating successful closed reduction: (a) Pre-reduction showing anterior dislocation with humeral head displaced inferomedially under the coracoid process. (b) Post-reduction showing humeral head concentrically located within the glenoid fossa with normal joint alignment restored. Always obtain post-reduction X-rays to confirm reduction and assess for associated fractures.Credit: Takase F et al., Case Rep Orthop - CC BY 4.0

Post-Reduction Steps

Repeat neurovascular exam (document!)
Post-reduction X-rays (confirm reduction)
Immobilize in sling
Provide analgesia
Arrange follow-up and MRI

Failed Reduction

Interposed tissue (rotator cuff, biceps)
Associated fracture blocking
Inadequate anesthesia
May need open reduction
Posterior dislocations often harder

Surgical Technique

Arthroscopic Bankart Repair

Operative Steps

PositioningStep 1

Beach chair or lateral decubitus with arm in traction. Author preference varies. Beach chair = easier orientation, lateral = better inferior access.

Portal PlacementStep 2

Posterior viewing portal (soft spot), anterior working portal (rotator interval), anteroinferior accessory portal for anchor placement.

Labral MobilizationStep 3

Elevate labrum off glenoid neck with elevator. Mobilize until subscapularis seen medially. Fresh bleeding edge essential.

Glenoid PreparationStep 4

Rasp glenoid rim to create bleeding bone bed. Do not over-decorticate (bone loss).

Anchor PlacementStep 5

3-4 suture anchors from 5 o'clock to 3 o'clock (right shoulder). Inferior anchors most important - capture IGHL.

Labral RepairStep 6

Pass sutures through labrum, tie sequentially. Goal: bumper effect restoration, recreate labral height on glenoid rim.

Technical Pearls

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

Pitfalls to Avoid

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

Complication	Incidence	Risk Factors	Management
Recurrent instability	10-15% after Bankart	Young age, contact sport, bone loss, poor tissue	Revision surgery, consider Latarjet
Axillary nerve injury	Up to 30% initial	Inferior dislocation, elderly, delayed reduction	Most recover 3-6 months, EMG at 3 months
Rotator cuff tear	Over 40 years: 40%	Age over 40, high-energy, recurrent	MRI assessment, repair if symptomatic
Stiffness/Frozen shoulder	5-10%	Prolonged immobilization, elderly	Early motion, physiotherapy
Osteoarthritis	10-20% long-term	Recurrent dislocations, bone loss	Activity modification, arthroplasty if severe
Vascular injury	Rare	High-energy, elderly (axillary artery)	Urgent vascular surgery consultation

Axillary Nerve Recovery

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

ProtectionWeek 0-2

Sling full-time. Pendulum exercises only. Ice and analgesia. No external rotation.

Early MotionWeek 2-6

Sling when out. Active elbow and hand. Passive forward flexion, ER to neutral only. No combined ABD+ER.

StrengtheningWeek 6-12

Wean sling. AROM all directions. Isometric then isotonic strengthening. Rotator cuff and scapular stabilizers.

Sport-SpecificMonth 3-6

Full ROM. Progressive resistance. Sport-specific drills. No contact until 6 months.

Return to SportMonth 6+

Full strength and ROM. Functional testing. Return to contact sport 6 months minimum.

Immobilization Position Controversy

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

Factor	Better Outcome	Worse Outcome
Age at first dislocation	Older (over 30)	Younger (under 20)
Number of dislocations	Single episode	Multiple recurrences
Bone loss	Minimal (under 15%)	Significant (over 25%)
Sport demands	Non-contact	Contact/collision sports
Tissue quality	Good labral tissue	Attenuated/ALPSA pattern

Evidence Base and Key Trials

Kirkley et al. - First-Time Dislocation RCT

Kirkley A et al. • J Bone Joint Surg Am (2005)

Key Findings:

RCT of first-time anterior dislocation in under 30s
Arthroscopic Bankart vs immobilization + physio
Recurrence: 15% surgery vs 47% conservative
Better WOSI scores with surgery

Clinical Implication: Early stabilization reduces recurrence in young first-time dislocators. Consider for under 25 in contact sports.

Limitation: Single surgeon, relatively small numbers.

Jakobsen et al. - Young Military Athletes

Jakobsen BW et al. • Arthroscopy (2007)

Key Findings:

RCT: First-time dislocators under 25
Arthroscopic Bankart vs conservative
Recurrence: 3% surgery vs 54% conservative at 10 years
NNT = 2 (treat 2 patients to prevent 1 recurrence)

Clinical Implication: Strong evidence for early surgery in young athletic patients.

Limitation: Military population, high-demand activity.

Glenoid Track Concept - Di Giacomo

Di Giacomo G et al. • Arthroscopy (2014)

Key Findings:

Defines engaging vs non-engaging Hill-Sachs
Glenoid track = 83% of glenoid width minus bone loss
Hill-Sachs medial to glenoid track = engaging (off-track)
Off-track lesions need additional procedure (remplissage)

Clinical Implication: Use glenoid track to determine if Bankart alone sufficient or if Hill-Sachs needs addressing.

Limitation: Biomechanical concept, clinical validation ongoing.

Latarjet vs Bankart Systematic Review

Bliven et al. • Orthop J Sports Med (2020)

Key Findings:

Meta-analysis comparing Latarjet vs Bankart
Latarjet lower recurrence (3% vs 11%)
Latarjet higher complication rate (15% vs 8%)
Latarjet for bone loss over 25% or failed Bankart

Clinical Implication: Latarjet more stable but higher complications. Reserve for bone loss or revision.

Limitation: Heterogeneous studies, selection bias.

Immobilization Position - Review

Paterson WH et al. • Cochrane Database (2010)

Key Findings:

Early studies suggested ER immobilization better
Meta-analysis found no significant difference
ER theoretically approximates Bankart to glenoid
Practical: IR immobilization remains standard

Clinical Implication: Either position acceptable. IR more practical and patient-tolerated.

Limitation: Variable protocols and compliance.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: First-Time Anterior Dislocation in Young Athlete

EXAMINER

"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?"

EXCEPTIONAL ANSWER

This is a first-time anterior shoulder dislocation in a 19-year-old AFL player - a challenging scenario given the high recurrence risk but also his desire for rapid return to elite sport. I would take a systematic approach: First, confirm the diagnosis with proper trauma series X-rays including axillary view to ensure reduction is maintained. Second, document neurovascular status, specifically axillary nerve function - test deltoid power and regimental badge sensation. Third, arrange an MRI to assess for Bankart lesion, Hill-Sachs size, and any SLAP or rotator cuff involvement. For management, I would counsel him that his recurrence risk is approximately 90% with conservative treatment given his age and contact sport. Evidence from Kirkley and Jakobsen RCTs shows arthroscopic Bankart repair reduces recurrence to 10-15%. I would recommend early arthroscopic stabilization before the season, which allows return to contact sport at 6 months with lower long-term recurrence risk. If he declines surgery, I would respect his autonomy but ensure he understands the recurrence risk and progressive bone loss that occurs with each dislocation.

KEY POINTS TO SCORE

Age under 20 + contact sport = 90% recurrence if conservative

Document axillary nerve function pre and post any intervention

MRI essential to assess labral injury, Hill-Sachs, bone loss

Evidence supports early stabilization in young athletic patients

Return to sport: 6 months post-Bankart repair minimum

COMMON TRAPS

✗Not documenting axillary nerve status

✗Not getting MRI to assess lesions

✗Not counseling about very high recurrence risk in this age group

✗Promising return to sport before 6 months

LIKELY FOLLOW-UPS

"What if MRI shows 30% glenoid bone loss?"

"What is the glenoid track concept?"

"How long return to sport after Latarjet?"

VIVA SCENARIOChallenging

Scenario 2: Missed Posterior Dislocation

EXAMINER

"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?"

EXCEPTIONAL ANSWER

This presentation is highly concerning for a missed posterior shoulder dislocation, which occurs in up to 50% of cases. The classic triad is present: post-seizure, fixed internal rotation, and inability to externally rotate. My immediate concern is that this is now a chronic locked posterior dislocation at 3 weeks. I would examine for the 'empty antecubital fossa' - the humeral head should not be palpable anteriorly. I would arrange urgent imaging: first, orthogonal X-rays including a true axillary lateral or Y-view (not just AP). I expect to see the 'lightbulb sign' on AP, with the head posterior to glenoid on axillary view. Then CT scan is essential to assess the size of the reverse Hill-Sachs (McLaughlin lesion), as this determines treatment. If the reverse Hill-Sachs is under 25%, I would attempt closed reduction under GA with good muscle relaxation. If 25-40%, open reduction with lesser tuberosity transfer (McLaughlin procedure) or allograft is needed. If over 40-50%, the patient may require arthroplasty. I would explain to him that this was unfortunately missed initially, and document my findings carefully.

KEY POINTS TO SCORE

Posterior dislocations missed 50% of time on AP X-ray alone

Triad: seizure/electrocution + fixed IR + cannot ER

ALWAYS get axillary view - never rely on AP alone

CT scan essential to assess reverse Hill-Sachs size

Treatment depends on defect size and chronicity

COMMON TRAPS

✗Accepting 'normal AP X-ray' without axillary view

✗Not getting CT to quantify reverse Hill-Sachs

✗Attempting closed reduction of chronic dislocation without planning

✗Not recognizing this may need more than closed reduction at 3 weeks

LIKELY FOLLOW-UPS

"What are the X-ray signs of posterior dislocation?"

"What is the McLaughlin procedure?"

"What percentage reverse Hill-Sachs needs arthroplasty?"

VIVA SCENARIOCritical

Scenario 3: Recurrent Instability with Bone Loss

EXAMINER

"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?"

EXCEPTIONAL ANSWER

This is a complex revision instability case with significant bone loss - a patient where isolated Bankart repair has already failed and would likely fail again. The key issues are: (1) 28% glenoid bone loss exceeds the 25% threshold, meaning soft tissue repair alone has high failure rate; (2) previous Bankart has failed suggesting tissue quality is poor; (3) young high-demand rugby player. For surgical options, my primary recommendation would be a **Latarjet procedure**. The Latarjet addresses his problem through the 'triple effect': bone block increases the glenoid arc, the conjoined tendon provides dynamic sling effect in ABER position, and the capsule is repaired to the CA ligament stump. Expected recurrence with Latarjet is 3-5% compared to 30%+ for revision Bankart with this bone loss. I would counsel about Latarjet-specific complications: nerve injury (musculocutaneous, suprascapular), nonunion of coracoid (5-10%), hardware issues, and future arthritis. Alternative options include the Eden-Hybinette (iliac crest bone graft) which avoids harvesting the coracoid but has less evidence. I would discuss return to rugby at 6-9 months post-Latarjet with appropriate rehabilitation.

KEY POINTS TO SCORE

28% glenoid bone loss = Latarjet indicated (threshold 25%)

Failed Bankart + bone loss = soft tissue repair will fail again

Latarjet triple effect: bone block, sling effect, capsular repair

Latarjet recurrence 3-5% vs revision Bankart 25-30%

Counsel about Latarjet complications particularly nerve injury

COMMON TRAPS

✗Recommending revision Bankart with this bone loss - will fail

✗Not quantifying bone loss with CT

✗Not addressing the failed previous surgery

✗Underestimating Latarjet complications

LIKELY FOLLOW-UPS

"Describe the Latarjet surgical technique"

"What is the glenoid track concept?"

"When would you consider Eden-Hybinette over Latarjet?"

MCQ Practice Points

Anatomy Question

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.

Clinical Question

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.

Recurrence Question

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.

Bone Loss Question

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.

Nerve Injury Question

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.

Lesion Question

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.

Australian Context

Epidemiology

High rate in AFL and rugby players
Peak incidence in 18-25 age group
Male predominance in sports injuries
Indigenous Australians higher contact sport participation

Healthcare Funding

Private health implications for young patients
Waiting lists for public surgery

Medicolegal Considerations

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.

SHOULDER DISLOCATIONS

High-Yield Exam Summary

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

Patient

Presentation

Treatment

Key Pearl

Young athlete under 20

First anterior dislocation

Consider early Bankart repair

90% recurrence if conservative

Adult 30-50 years

First anterior dislocation

Conservative, sling 2-4 weeks

Activity modification, physio

Elderly over 60

First anterior dislocation

Conservative, early motion

Check rotator cuff - high tear rate

Any age

Posterior dislocation

Urgent CT scan after reduction

50% missed on AP - always axillary view

Any age

Recurrent instability

Surgical stabilization

Assess bone loss - Bankart vs Latarjet

Structure

Function

Injury Pattern

Glenoid labrum

Deepens socket by 50%, bumper effect

Bankart lesion (anterior), Kim lesion (posterior)

IGHL (Inferior Glenohumeral Ligament)

Primary restraint in ABER position

Torn in anterior dislocation

MGHL (Middle GHL)

Restraint in 45° abduction

Variable anatomy (absent in 30%)

SGHL (Superior GHL)

Resists inferior translation at rest

Less relevant to dislocation

Coracohumeral ligament

Resists external rotation at rest

Posterior dislocation injury

Type

Frequency

Mechanism

Key Features

Anterior (Subcoracoid)

95%

ABER position - Abduction + External Rotation

Bankart lesion + Hill-Sachs, axillary nerve at risk

Posterior

3-4%

Seizure, electrocution, direct blow

50% missed on AP - lightbulb sign, fixed IR

Inferior (Luxatio Erecta)

Less than 1%

Hyperabduction - arm locked overhead

Highest nerve injury rate, rotator cuff tears

Multidirectional

Variable

Atraumatic instability, generalized laxity

Requires different surgical approach

Lesion

Location

Incidence

Significance

Bankart lesion

Anterior labrum avulsion

67-97%

Essential lesion - repair for stability

Hill-Sachs lesion

Posterolateral humeral head

40-90%

Engaging lesion needs addressing

Bony Bankart

Anterior glenoid fracture

5-10%

Bone loss over 25% needs Latarjet

HAGL lesion

Humeral avulsion of GHL

2-10%

Often missed, repair to humerus

ALPSA lesion

Anterior labrum periosteal sleeve avulsion

Variable

Medially displaced labrum, heals poorly

Rotator cuff tear

Supraspinatus usually

Variable by age

Over 40 years: up to 40% incidence

Finding

Posterior

Arm position

Abducted, externally rotated

Adducted, internally rotated (fixed)

Humeral head

Palpable anteriorly

Not palpable anteriorly (empty)

Shoulder contour

Squared off, flattened

Flattened anteriorly, fullness posteriorly

Movement

Unable to internally rotate

Unable to externally rotate (locked)

Common miss

Rarely missed

Missed 50% of time!

Imaging Protocol

First LinePlain Radiographs - Trauma Series

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.

If Posterior SuspectedAxillary Lateral (Essential)

Shows head position relative to glenoid. If patient cannot abduct (Velpeau view alternative - arm across chest, lean back for axillary).

Post-ReductionRepeat X-rays

Confirm reduction with repeat trauma series. Document any fractures visible post-reduction.

Definitive AssessmentMRI or CT

MRI: Best for labrum (Bankart), capsule, rotator cuff. CT: Best for bone loss quantification (glenoid and humeral).

X-ray Signs of Posterior Dislocation

Lightbulb Sign

Humeral head appears round like a lightbulb on AP due to internal rotation. Loss of normal head contour.

Rim Sign

Increased distance between medial head and anterior glenoid rim (over 6mm). Joint space widening.

Trough Sign

Vertical sclerotic line on medial humeral head = reverse Hill-Sachs impaction fracture visible en face.

Lost Half-Moon

Normal overlap of humeral head on glenoid rim is lost when head displaces posteriorly.

Complication

Incidence

Risk Factors

Management

Recurrent instability

10-15% after Bankart

Young age, contact sport, bone loss, poor tissue

Revision surgery, consider Latarjet

Axillary nerve injury

Up to 30% initial

Inferior dislocation, elderly, delayed reduction

Most recover 3-6 months, EMG at 3 months

Rotator cuff tear

Over 40 years: 40%

Age over 40, high-energy, recurrent

MRI assessment, repair if symptomatic

Stiffness/Frozen shoulder

5-10%

Prolonged immobilization, elderly

Early motion, physiotherapy

Osteoarthritis

10-20% long-term

Recurrent dislocations, bone loss

Activity modification, arthroplasty if severe

Vascular injury

Rare

High-energy, elderly (axillary artery)

Urgent vascular surgery consultation

Factor

Better Outcome

Worse Outcome

Age at first dislocation

Older (over 30)

Younger (under 20)

Number of dislocations

Single episode

Multiple recurrences

Bone loss

Minimal (under 15%)

Significant (over 25%)

Sport demands

Non-contact

Contact/collision sports

Tissue quality

Good labral tissue

Attenuated/ALPSA pattern

Structure	Function	Clinical Relevance
Subscapularis	Anterior rotator cuff, internal rotation	Lesser tuberosity avulsion, anterior stabilizer
Rotator cuff (all)	Compresses head into glenoid	Balanced force couple, elderly tears
Biceps long head	Humeral head depression	SLAP lesions with instability
Scapular stabilizers	Maintain glenoid position	Scapular dyskinesis worsens instability

Pole	Type	Characteristics	Treatment
Pole I (Structural)	Traumatic	Single direction, Bankart lesion	Arthroscopic Bankart repair
Pole II (Atraumatic)	Hyperlaxity	Multidirectional, no structural lesion	Rehabilitation focused
Pole III (Muscle Patterning)	Habitual/Voluntary	Abnormal muscle recruitment patterns	Psychology referral, therapy

Factor	Points
Age under 20 years	2
Contact/forced overhead sport	2
Hyperlaxity	1
Hill-Sachs on AP X-ray	2
Glenoid bone loss on AP X-ray	2
Total	0-10

Lesion	Location	Significance
Reverse Bankart	Posterior labrum avulsion	Repair for posterior stability
Reverse Hill-Sachs (McLaughlin)	Anteromedial humeral head	May need bone grafting or McLaughlin transfer
Posterior glenoid fracture	Posterior glenoid rim	Bone loss assessment needed
Kim lesion	Incomplete posterior labral tear	Subtle MRI finding

Structure	Sequence	Finding
Bankart lesion	Fat-suppressed T2, MR arthrogram	Anterior labrum avulsion with periosteal stripping
ALPSA lesion	MR arthrogram	Medially displaced labrum adherent to scapular neck
HAGL lesion	Coronal T2	Humeral-side avulsion of IGHL - J-sign
Hill-Sachs	Axial T2	Posterolateral humeral head defect
Rotator cuff	T2 coronal and sagittal	Tear assessment especially in over 40s

Age Group	Recurrence Risk	Management	Evidence
Under 20 years	90%	Consider early arthroscopic Bankart repair	RCTs show reduced recurrence
20-30 years, athlete	60-70%	Consider early stabilization in contact sport	Shared decision-making
30-40 years	40-50%	Conservative, physio, reassess if recurs	Recurrence lower, surgery if fails
Over 40 years	Under 25%	Conservative, check rotator cuff on MRI	High cuff tear rate - address if present

Procedure	Indication	Key Points
Arthroscopic Bankart repair	Glenoid bone loss under 25%, no engaging Hill-Sachs	Gold standard soft tissue repair, 10-15% recurrence
Latarjet procedure	Glenoid bone loss over 25%, revision Bankart failure	Coracoid transfer, sling effect, bone block, 5% recurrence
Remplissage	Large Hill-Sachs, off-track lesion	Infraspinatus tenodesis into Hill-Sachs defect
Open Bankart repair	HAGL lesion, capsular shift needed	Lower recurrence in some studies, bigger incision
Bone grafting	Large reverse Hill-Sachs (posterior)	McLaughlin, allograft, or arthroplasty if severe

Reverse Hill-Sachs Size	Management
Under 20%	Immobilize in external rotation, physiotherapy
20-40%	Lesser tuberosity transfer (McLaughlin) or allograft
40-50%	Consider hemiarthroplasty or reverse TSA
Over 50%	Arthroplasty (reverse TSA in elderly)

Shoulder Dislocations

Shoulder Dislocations

SHOULDER DISLOCATIONS - ANTERIOR VS POSTERIOR

DIRECTION OF DISLOCATION

Critical Must-Knows

Examiner's Pearls

Clinical Imaging

Imaging Gallery

Critical Shoulder Dislocation Exam Points

Do NOT Miss Posterior!

Age = Recurrence

Axillary Nerve

Associated Lesions

Quick Decision Guide

ABERAnterior Dislocation Features

SEIZEPosterior Dislocation Causes

LIGHTSX-ray Signs of Posterior Dislocation

AXILLARYNerve at Risk in Shoulder Dislocation

Overview and Epidemiology

Demographics

Impact

Anatomy and Mechanism

Key Anatomical Concept

Static Stabilizers

Dynamic Stabilizers

Mechanism by Direction

Anterior Dislocation (95%)

Posterior Dislocation (3-4%)

Inferior Dislocation (Luxatio Erecta)

Classification Systems

Classification by Direction of Dislocation

Instability Classification Systems

TUBS

AMBRI

Bone Loss Assessment

Glenoid Bone Loss Thresholds

Associated Lesions

Lesions with Anterior Dislocation

Lesions with Posterior Dislocation

Reverse Hill-Sachs Size

Clinical Assessment

History

Examination - Anterior

Anterior vs Posterior Clinical Signs

Posterior Dislocation - Don't Miss It!

Investigations

Imaging Protocol

X-ray Signs of Posterior Dislocation

Lightbulb Sign

Rim Sign

Trough Sign

Lost Half-Moon

MRI for Instability

CT for Bone Loss Quantification

Management Algorithm

Pre-Reduction Checklist

Reduction Techniques - Anterior Dislocation

Reduction Methods

Post-Reduction Steps

Failed Reduction

First-Time Anterior Dislocation Management

Surgical Options for Recurrent Instability

Latarjet Complications

Posterior Dislocation Management

Management Steps

Surgical Technique

Arthroscopic Bankart Repair

Operative Steps

Technical Pearls

Pitfalls to Avoid

Latarjet Coracoid Transfer

Key Steps

Complications

Axillary Nerve Recovery

Postoperative Care and Rehabilitation

Rehabilitation After Bankart Repair

Outcomes and Prognosis

Evidence Base and Key Trials

Kirkley et al. - First-Time Dislocation RCT

Jakobsen et al. - Young Military Athletes