Shoulder Instability Examination

Commonly Tested

Shoulder instability examination requires assessment of anterior, posterior, and inferior laxity. Examiners expect you to differentiate between laxity (asymptomatic translation) and instability (symptomatic), recognize the apprehension-relocation sequence, and identify multidirectional instability (MDI).

Exam day cheat sheet

Shoulder Instability Examination Summary

Key Concepts

Laxity ≠ Instability (laxity is normal translation, instability is symptomatic)
TUBS: Traumatic, Unilateral, Bankart, Surgery
AMBRI: Atraumatic, Multidirectional, Bilateral, Rehab, Inferior capsular shift

Anterior Instability

Apprehension test (most important)
Relocation test
Anterior drawer/load-shift
Surprise test (release)

Posterior Instability

Posterior apprehension
Jerk test
Kim test
Posterior drawer

Inferior/MDI

Sulcus sign
Beighton score (generalized hyperlaxity)
Gagey test (inferior laxity)

Introduction

Key Concepts

Laxity vs Instability:

Laxity: Asymptomatic translation (may be constitutional)
Instability: Symptomatic translation causing pain, apprehension, or giving way

Classification:

Etiology

TUBS: Traumatic
AMBRI: Atraumatic

Direction

TUBS: Unilateral (anterior 95%)
AMBRI: Multidirectional

Lesion

TUBS: Bankart
AMBRI: Bilateral capsular laxity

Treatment

TUBS: Surgery (often)
AMBRI: Rehabilitation (first line), Inferior capsular shift

Type	TUBS	AMBRI
Etiology	Traumatic	Atraumatic
Direction	Unilateral (anterior 95%)	Multidirectional
Lesion	Bankart	Bilateral capsular laxity
Treatment	Surgery (often)	Rehabilitation (first line), Inferior capsular shift

Direction of Instability:

Anterior: 95% of traumatic dislocations
Posterior: 2-4% (often voluntary or atraumatic)
Multidirectional: Bilateral, generalized hyperlaxity

General Assessment

Before Specific Tests

Look:

Deltoid wasting (axillary nerve injury)
Scapular dyskinesia
Previous surgical scars
Muscle bulk asymmetry

Generalized Hyperlaxity (Beighton Score):

Passive little finger MCP extension greater than 90° (each hand)

Points: 1 each

Passive thumb to forearm (each hand)

Points: 1 each

Elbow hyperextension greater than 10° (each arm)

Points: 1 each

Knee hyperextension greater than 10° (each leg)

Points: 1 each

Palms flat on floor with knees straight

Points: 1

Total

Points: 9

Test	Points
Passive little finger MCP extension greater than 90° (each hand)	1 each
Passive thumb to forearm (each hand)	1 each
Elbow hyperextension greater than 10° (each arm)	1 each
Knee hyperextension greater than 10° (each leg)	1 each
Palms flat on floor with knees straight	1
Total	9

Score greater than 4/9 = generalized hyperlaxity (relevant for MDI)

Anterior Instability Tests

Special test

Apprehension Test (Crank Test)

Anterior instability

Technique

1Patient supine, shoulder at edge of bed
2Arm abducted to 90°, elbow flexed 90°
3Externally rotate arm while applying gentle anterior pressure to humeral head from behind

Positive Sign

Apprehension (not just pain) - patient feels shoulder will dislocate, resists further movement

Indicates

Anterior instability

Diagnostic Accuracy

Sensitivity72%

Ability to detect true positives

Specificity96%

Ability to exclude false positives

Special test

Relocation Test (Jobe's)

Confirm anterior instability

Technique

1Perform apprehension test until positive
2Apply posterior force to humeral head (push from front)

Positive Sign

Relief of apprehension when posterior force applied

Indicates

Anterior instability (relocation prevents subluxation)

Diagnostic Accuracy

Sensitivity81%

Ability to detect true positives

Specificity92%

Ability to exclude false positives

Special test

Surprise (Release) Test

Confirm anterior instability

Technique

1From positive relocation position
2Suddenly release posterior stabilizing force

Positive Sign

Return of apprehension or pain when force released

Indicates

Anterior instability (highly specific)

Diagnostic Accuracy

Sensitivity64%

Ability to detect true positives

Specificity99%

Ability to exclude false positives

Special test

Anterior Drawer Test

Anterior laxity

Technique

1Patient supine, arm at 80-120° abduction, slight forward flexion
2Stabilize scapula with one hand
3Pull humeral head anteriorly with other hand

Positive Sign

Increased anterior translation compared to opposite side

Indicates

Anterior laxity (not necessarily instability)

Diagnostic Accuracy

Sensitivity53%

Ability to detect true positives

Specificity85%

Ability to exclude false positives

Special test

Load and Shift Test

Quantify translation (anterior and posterior)

Technique

1Patient seated, examiner behind
2One hand stabilizes scapula, other grasps humeral head
3Load humeral head into glenoid, then translate anteriorly and posteriorly

Positive Sign

Graded translation: Grade I: Translation to glenoid rim. Grade II: Over rim with spontaneous reduction. Grade III: Over rim, stays dislocated

Indicates

Direction and degree of laxity

Diagnostic Accuracy

Sensitivity72%

Ability to detect true positives

Specificity85%

Ability to exclude false positives

Posterior Instability Tests

Special test

Posterior Apprehension Test

Posterior instability

Technique

1Patient supine, arm forward flexed to 90°
2Apply axial load through elbow and internal rotation
3Push humeral head posteriorly

Positive Sign

Apprehension or pain as humeral head subluxates posteriorly

Indicates

Posterior instability

Diagnostic Accuracy

Sensitivity50%

Ability to detect true positives

Specificity90%

Ability to exclude false positives

Special test

Jerk Test

Posterior instability

Technique

1Patient seated, arm forward flexed 90°, adducted across body, internally rotated
2Apply axial load through elbow
3Horizontally adduct arm (move elbow toward opposite shoulder)

Positive Sign

Clunk as humeral head subluxates posteriorly, then reduces on returning to neutral

Indicates

Posterior instability

Diagnostic Accuracy

Sensitivity73%

Ability to detect true positives

Specificity98%

Ability to exclude false positives

Special test

Kim Test

Posteroinferior instability

Technique

1Patient seated, arm abducted 90°
2Examiner applies axial load while adducting arm 45° and applying posteroinferior force

Positive Sign

Pain and posterior clunk

Indicates

Posteroinferior instability

Diagnostic Accuracy

Sensitivity80%

Ability to detect true positives

Specificity94%

Ability to exclude false positives

Inferior Instability and MDI Tests

Special test

Sulcus Sign

Inferior laxity

Technique

1Patient seated, arm relaxed at side
2Grasp elbow and apply downward traction

Positive Sign

Sulcus (hollow) appears below acromion. Graded: I: less than 1cm. II: 1-2cm. III: greater than 2cm

Indicates

Inferior laxity (positive in MDI)

Diagnostic Accuracy

Sensitivity28%

Ability to detect true positives

Specificity97%

Ability to exclude false positives

Special test

Modified Sulcus Sign

Rotator interval competency

Technique

1Perform sulcus sign with arm in neutral
2Repeat with arm in external rotation

Positive Sign

Sulcus persists in external rotation (normally reduces)

Indicates

Rotator interval incompetence (significant MDI)

Diagnostic Accuracy

Sensitivity50%

Ability to detect true positives

Specificity90%

Ability to exclude false positives

Special test

Gagey Test (Hyperabduction)

Inferior capsule laxity

Technique

1Patient seated, examiner behind
2Stabilize scapula with one hand pressing down on acromion
3Passively abduct arm with other hand

Positive Sign

Abduction greater than 105° with scapula stabilized

Indicates

Inferior glenohumeral ligament laxity

Diagnostic Accuracy

Sensitivity88%

Ability to detect true positives

Specificity91%

Ability to exclude false positives

Interpretation

Clinical Patterns

TUBS Pattern (Traumatic Anterior):

Young patient with clear traumatic event
Unilateral symptoms
Positive apprehension-relocation
Often requires surgical repair (Bankart)

AMBRI Pattern (Atraumatic MDI):

Bilateral symptoms or laxity
Generalized hyperlaxity (Beighton score high)
Positive sulcus sign (both sides)
Initial treatment: rehabilitation (scapular stabilization)
Surgery: inferior capsular shift if conservative fails

Posterior Instability Pattern:

Often young athletes (weightlifters, rugby)
May be voluntary
Positive jerk test, posterior apprehension
Consider bone loss (reverse Hill-Sachs)

Key Concept

Apprehension is Key: The apprehension test is most sensitive and specific when it elicits APPREHENSION (feeling of impending dislocation), not just pain. Pain alone may be from other pathology (impingement, labral tear).

Summary Presentation

Viva scenarioStandard

Presenting Your Findings

Clinical prompt

“22-year-old male rugby player with history of anterior shoulder dislocation 6 months ago. Now has recurrent 'giving way' of the shoulder.”

Comparison Table

Traumatic Anterior (TUBS)

history: Clear dislocation event
examination: Apprehension +, Relocation +
laxity: Unilateral
treatment: Often surgical

MDI (AMBRI)

history: Atraumatic, gradual onset
examination: Bilateral laxity, Sulcus +
laxity: Bilateral
treatment: Rehabilitation first

Posterior

history: May be voluntary or post-trauma
examination: Jerk test +, Posterior apprehension +
laxity: May be bilateral
treatment: Rehab, surgery if fails

Voluntary

history: No true instability, psychological
examination: Can voluntarily sublux
laxity: Variable
treatment: Avoid surgery, psychology

pattern	history	examination	laxity	treatment
Traumatic Anterior (TUBS)	Clear dislocation event	Apprehension +, Relocation +	Unilateral	Often surgical
MDI (AMBRI)	Atraumatic, gradual onset	Bilateral laxity, Sulcus +	Bilateral	Rehabilitation first
Posterior	May be voluntary or post-trauma	Jerk test +, Posterior apprehension +	May be bilateral	Rehab, surgery if fails
Voluntary	No true instability, psychological	Can voluntarily sublux	Variable	Avoid surgery, psychology

Examiner Tips

Exam day cheat sheet

Scoring High in Instability Examination

Do

Perform full apprehension-relocation-release sequence
Test all three directions
Compare both shoulders
Assess Beighton score for hyperlaxity
Ask about direction of giving way

Don't

Accept pain alone as positive apprehension
Forget posterior instability
Miss sulcus sign for MDI
Examine too aggressively in acute dislocation
Forget to examine rotator cuff (may coexist)