Glenohumeral Instability
Upper LimbOverview
Glenohumeral instability is a condition characterized by excessive translation of the humeral head within the glenoid fossa, resulting from compromised dynamic or static stabilizers. This can manifest as anterior, posterior, inferior, or multidirectional patterns, with varying degrees of severity from microinstability to frank dislocation. Patients typically present with apprehension, pain, and functional limitations in specific arm positions.
Pathophysiology
The glenohumeral joint relies on a complex balance of static stabilizers (labrum, articular cartilage, joint capsule, and ligaments) and dynamic stabilizers (rotator cuff muscles and scapular stabilizers). Instability develops through traumatic injury (Bankart lesions, HAGL lesions, Hill-Sachs defects), repetitive microtrauma, inherent ligamentous laxity, or neuromuscular dysfunction. Compromised proprioception, altered scapulohumeral rhythm, and weakness in rotator cuff or scapular stabilizers perpetuate the unstable pattern. Chronic instability leads to degenerative changes, further articular surface damage, and secondary impingement.
Typical Presentation
Site
Anterior glenohumeral joint region; pain may radiate to lateral shoulder and upper arm; posterior shoulder pain if posterior instability
Quality
Sharp, catching sensation; sense of shoulder 'slipping' or 'dead arm' phenomenon; aching or dull discomfort with functional activities
Intensity
Variable, typically mild to moderate at rest, severe with provocative positions or functional demands; intensity increases with fatigue
Aggravating
Abduction with external rotation (throwing position, overhead activities); sudden arm movements; certain sleeping positions; fatigue during repetitive activities; specific arm positions (apprehension position); overhead sports
Relieving
Rest and immobilization; internal rotation positioning; anti-inflammatory modalities; controlled movement patterns; scapular stabilization
Associated
Apprehension and fear of movement; loss of proprioception; scapular dyskinesis; reduced rotator cuff strength; clicking or clunking sensations; difficulty with overhead activities; functional weakness; anterior shoulder capsule tightness; posterior capsule tightness (posterior instability)
Orthopaedic Tests
Surprise/Release Test (Jerk Test Variant)
Procedure
Patient supine; examiner reproduces apprehension position (90° abduction, external rotation) then suddenly releases posterior pressure (if applied) or suddenly shifts hand position to assess patient reaction.
Positive Finding
Patient guards or shows fear response when support is withdrawn; apprehension returns or worsens
Sensitivity / Specificity
Reference: Lo IK et al., Am J Sports Med 2004; PMID 14977651
Interpretation
Supplementary test to confirm psychological component and apprehension response to perceived instability. Lacks strong diagnostic validation in literature but clinically useful to differentiate apprehension from pain. Lo (2004) found the surprise (anterior release) test the single most accurate of the three instability tests (64% sensitivity / 99% specificity); apprehension and relocation alone were less accurate.
Apprehension Test (Crank Test)
Procedure
Patient supine or seated; shoulder abducted to 90° and externally rotated. Positive response is apprehension that the humeral head will dislocate anteriorly.
Positive Finding
Patient reports apprehension (fear of dislocation) rather than pain alone
Related reference: Lo IK et al., Am J Sports Med 2004; PMID 14977651
Interpretation
High specificity for anterior glenohumeral instability; apprehension is more specific than pain. Negative test helps rule out anterior instability. Apprehension and relocation tests alone are less accurate than the surprise test (Lo 2004); no confirmed sensitivity/specificity pair is shown.
Relocation Test (Jobe Relocation Test)
Procedure
Performed immediately after positive apprehension test. Examiner applies posterior-directed pressure to the humeral head while shoulder remains in 90° abduction and external rotation.
Positive Finding
Reduction or elimination of apprehension with posterior pressure applied to humeral head
Related reference: Lo IK et al., Am J Sports Med 2004; PMID 14977651
Interpretation
Increases confidence in anterior instability diagnosis when apprehension test is positive and relocation abolishes apprehension. Strengthens diagnostic accuracy when used as a cluster with apprehension test. Apprehension and relocation tests alone are less accurate than the surprise test (Lo 2004); no confirmed sensitivity/specificity pair is shown.
Anterior Drawer Test (Sulcus Sign Modified for Anterior Translation)
Procedure
Patient seated or supine; examiner grasps humeral head with one hand and translates it anteriorly while the other hand stabilizes the scapula. Movement is assessed qualitatively or with ruler measurement.
Positive Finding
Excessive anterior humeral head translation (>1 cm or grade 2–3 on a scale of 0–3)
Interpretation
High specificity suggests anterior instability when positive; low-moderate sensitivity means negative test does not reliably exclude instability. Useful to confirm laxity when apprehension tests are equivocal.
Sulcus Sign (Inferior Instability)
Procedure
Patient seated with arms at side and relaxed. Examiner applies downward traction on the humerus and observes for a sulcus (depression) below the acromion.
Positive Finding
Visible or palpable sulcus depression below the acromion with downward traction; graded 0–3 (grade ≥2 considered positive)
Interpretation
Indicates inferior glenohumeral instability or multidirectional instability. Presence suggests capsular laxity and may indicate need for non-operative rehabilitation focusing on rotator cuff and scapular control.
Crank Test (External Rotation at 0° Abduction)
Procedure
Patient prone or supine with shoulder at 0° abduction and elbow flexed 90°. Examiner externally rotates the shoulder, noting range and resistance.
Positive Finding
Excessive external rotation (>75°) compared to contralateral side, or reproduction of apprehension during movement
Interpretation
Assesses anterior capsular laxity and proprioceptive feedback. Positive test suggests anterior or multidirectional instability, especially when combined with apprehension or relocation tests.
⚠ Red Flags
- •Acute glenohumeral dislocation requiring emergency reduction
- •Neurovascular compromise (axillary nerve injury, vascular injury)
- •Significant bony defects (Hill-Sachs lesion >25%, glenoid bone loss >20%) requiring surgical intervention
- •Fracture-dislocation or associated fractures
- •Recurrent dislocation episodes (>2 dislocations, especially in contact athletes)
- •Failed conservative management with persistent instability despite 3+ months of structured therapy
- •Signs of associated labral pathology with mechanical locking or catching
- •Systemically hypermobile Ehlers-Danlos syndrome or Marfan syndrome requiring specialist assessment
⚡ Yellow Flags
- •High-level athlete with instability affecting career/livelihood
- •Fear-avoidance beliefs preventing engagement in rehabilitation
- •Repeated injury pattern suggesting possible inadequate rehabilitation compliance
- •Psychological distress related to injury and functional limitations
- •Secondary gains associated with chronic shoulder dysfunction
- •Perfectionist or high-performance athlete mentality affecting recovery pacing
- •Limited coping mechanisms for managing shoulder function restrictions
- •Anxiety regarding re-dislocation during rehabilitation progression
Osteopathic Techniques
Region
Glenohumeral joint and anterior capsule
Technique
Rationale
Targeted soft tissue mobilization to anterior shoulder structures, pectoralis minor, and subscapularis releases tension in capsular tissues, improves local circulation, and prepares tissues for mobilization. Reduces protective muscle guarding and facilitates proprioceptive input.
Region
Posterior shoulder capsule and infraspinatus
Technique
Rationale
Muscle energy techniques addressing posterior capsule tightness are essential in anterior instability patterns where posterior capsule contracture contributes to altered scapulohumeral mechanics. Restores balanced capsular tension and reduces compensatory anterior translation.
Region
Glenohumeral joint
Technique
Rationale
Gentle passive articulation through pain-free ranges promotes synovial fluid distribution, enhances proprioceptive awareness, and maintains accessory motion patterns without aggressive mobilization that may exacerbate instability. Builds confidence in movement patterns.
Region
Scapulothoracic joint and associated musculature
Technique
Rationale
Release of upper trapezius, levator scapulae, and pectoralis minor facilitates normalized scapular positioning. Correcting scapular dyskinesis is fundamental to restoring dynamic stability and reducing compensatory glenohumeral translation.
Region
Cervical spine and cervicothoracic junction
Technique
Rationale
Cervical and cervicothoracic restrictions limit shoulder girdle positioning and proprioceptive input from cervical mechanoreceptors. Gentle articulation restores cervical-scapular coordination and upper quarter neurodynamics essential for shoulder stability.
Rehabilitation Exercises
Pendulum Circles
Cross-Body Shoulder Stretch (Horizontal Adduction)
Sleeper Stretch (Posterior Capsule)
Scapular Retraction with Prone Walkout
Isometric External Rotation (Neutral Position)
Prone Shoulder External Rotation with Band
Prone Horizontal Abduction at 90 Degrees
Lower Trapezius Activation (90/90 Position)
Quadruped Shoulder Taps
Prone Push-up with Scapular Emphasis
PNF D2 Flexion Pattern (Standing with Resistance Band)
Submaximal Rowing Machine (Controlled Ergometer)
Referral Criteria
- •Acute dislocation or recurrent dislocations (>2 episodes) requiring orthopedic evaluation for imaging and surgical consideration
- •Failure to progress after 8-12 weeks of structured conservative management
- •Severe pain with significant functional limitations unresponsive to manual therapy and exercise
- •Clinical suspicion of labral pathology (SLAP lesion, Bankart lesion) with positive imaging findings
- •Significant bony defects or fracture-dislocation requiring surgical stabilization
- •High-demand athletes seeking return to contact or overhead sports requiring specialist clearance
- •Neurovascular compromise or axillary nerve injury
- •Systemic connective tissue disorders (Ehlers-Danlos, Marfan syndrome) requiring multidisciplinary team approach
- •Persistent instability despite optimal rehabilitation suggesting possible undiagnosed pathology
- •Mental health concerns or significant psychological distress interfering with rehabilitation engagement