Populations and Risk Factors
- Young athletes in contact sports (most frequent): rugby, football, hockey, wrestling — high-velocity collision or fall forces the joint beyond its physiological limits; anterior GH dislocation typically occurs during forced abduction + external rotation
- Age and recurrence: first-time dislocation under age 20 carries approximately 90% recurrence risk; age 20-30 carries approximately 60-70% recurrence risk; age 30-40 carries approximately 30% risk; over age 40 carries approximately 10% risk — younger patients have greater tissue elasticity but more years of exposure to reinjury
- Generalized joint hypermobility: conditions such as Ehlers-Danlos syndrome or Marfan syndrome predispose to multidirectional instability and recurrent dislocations across multiple joints
- History of previous dislocations: each dislocation further stretches the capsule, damages the labrum, and deepens osseous defects (Hill-Sachs, bony Bankart) — creating a self-perpetuating cycle of instability with progressively less force required to dislocate
- Children: radial head dislocation ("nursemaid's elbow") is the most common upper limb dislocation in children under 5 — caused by sudden longitudinal traction on an extended, pronated forearm (pulled by a parent or caregiver)
- Older adults (over 40): first-time GH dislocation is more likely to be associated with concurrent rotator cuff tear (the cuff fails before the labrum in older, stiffer tissue) — up to 35% of first dislocations over age 40 have an associated RC tear
- Posterior GH dislocations are rare (approximately 2-5%) and classically associated with seizures and electrocution (massive simultaneous contraction of all shoulder muscles, with the stronger internal rotators overpowering external rotators)
Causes and Pathophysiology
Mechanism of Dislocation
- Dislocation occurs when an external force exceeds the combined restraining capacity of the joint's passive stabilizers (capsule, ligaments, labrum, bony congruence) and active stabilizers (muscles, tendons). The force magnitude, direction, and speed determine which structures fail.
- Anterior GH dislocation (95% of shoulder dislocations): The mechanism is forced abduction + external rotation + extension. The humeral head is driven anteriorly and inferiorly, levering over the anterior glenoid rim. The force tears the anteroinferior joint capsule and avulses the anteroinferior glenoid labrum (Bankart lesion). Simultaneously, the posterolateral humeral head impacts the anterior glenoid rim, producing a compression fracture (Hill-Sachs lesion).
- Posterior GH dislocation (2-5%): The mechanism is forced internal rotation + adduction + flexion. Classically caused by seizures or electrocution (massive IR torque overpowers ER muscles). The humeral head is driven posteriorly. A reverse Hill-Sachs lesion (compression fracture on the anteromedial humeral head) and reverse Bankart lesion (posterior labral avulsion) may occur.
- Inferior GH dislocation (luxatio erecta, < 1%): The arm is forced into hyperabduction. The humeral head is displaced inferiorly with the arm locked overhead. High association with rotator cuff tears, axillary nerve damage, and axillary artery injury. This is a medical emergency.
Circle Concept of Instability
- The GH joint capsule and ligaments form a continuous ring (circle) around the joint. Injury to one side of the circle frequently produces damage on the opposite side as well. An anterior dislocation damages the anterior capsule and labrum (Bankart) but also creates a posterior humeral head defect (Hill-Sachs). Understanding this bipolar injury pattern is essential for predicting recurrence risk and treatment planning.
Bankart and Hill-Sachs Lesions
- Bankart lesion: Avulsion of the anteroinferior glenoid labrum with or without capsular detachment. Eliminates the primary passive restraint against anterior humeral head translation. Present in approximately 90% of traumatic first-time anterior dislocations in young adults. A bony Bankart (labral avulsion with glenoid rim fracture) further reduces the concavity-compression stabilization mechanism and significantly increases recurrence risk.
- Hill-Sachs lesion: Compression fracture of the posterolateral humeral head. Found in approximately 80% of first-time dislocations and nearly 100% of recurrent dislocations. An "engaging" Hill-Sachs defect (one large enough to interact with the anterior glenoid rim during functional positions of ER and abduction) creates a mechanical catch that can trigger repeat dislocation.
Capsular Laxity and Recurrence
- Each dislocation event stretches and further damages the joint capsule. The capsule does not fully recover its original tension — residual laxity remains after each episode. This is why recurrence risk increases with each dislocation, and progressively less force is required to produce subsequent events.
- In recurrent dislocators, the capsule becomes so lax that voluntary or involuntary subluxation can occur with normal daily activities (reaching overhead, rolling over in bed). At this stage, the joint is considered chronically unstable.
Neurovascular Injury
- The axillary nerve wraps around the surgical neck of the humerus and is vulnerable during anterior dislocation. Axillary nerve injury occurs in approximately 5-35% of anterior GH dislocations — more common in older patients and with longer dislocation duration before reduction. Clinical finding: numbness over the lateral deltoid (regimental badge area) and weakness of deltoid and teres minor.
- The axillary artery can be damaged by the displaced humeral head, particularly in inferior dislocations (luxatio erecta). Vascular injury presents as absent or diminished distal pulses, pallor, coolness, and mottled skin in the hand and forearm. This is a surgical emergency.
- The brachial plexus may be stretched or compressed by the displaced humeral head, producing widespread upper extremity neurological deficits beyond the axillary nerve distribution.
Post-Reduction Considerations
- After reduction (relocation of the joint), the damaged structures must heal. The standard approach is a period of immobilization (sling) followed by progressive rehabilitation.
- Immobilization position controversy: Traditional immobilization is in internal rotation (arm in a sling across the body). Recent evidence suggests immobilization in external rotation may produce better labral healing by keeping the Bankart lesion approximated to the glenoid rim — however, compliance is lower and evidence remains debated.
- Rehabilitation follows a phased approach: Phase 1 — pain control, protected ROM (pendulums, passive within safe range); Phase 2 — progressive AROM, isometric then isotonic RC strengthening; Phase 3 — dynamic stability, sport-specific training, return to activity. Premature loading risks re-dislocation; insufficient rehabilitation risks chronic instability.
Signs and Symptoms
Acute Dislocation (Unreduced)
- Obvious displacement or visible misalignment of bones (deformity) — in anterior GH dislocation, the normal rounded deltoid contour is lost (squared-off shoulder), and the humeral head may be palpable anteriorly
- Loss of function; joint fixed in one position (anterior GH: arm held in slight abduction and ER; patient cannot bring arm to the side)
- Intense pain with a "popping" sensation at the moment of injury and immediate swelling
- Severe muscle guarding — involuntary spasm of surrounding muscles to prevent any movement of the dislocated joint
- Apprehension when the joint is moved toward the dislocating position
Post-Reduction / Chronic Instability
| Finding | First Dislocation (Post-Reduction) | Recurrent Instability |
|---|---|---|
| Pain | Significant; resolves over weeks | Less with each episode; may be minimal |
| Swelling | Moderate to severe | Minimal (capsule stretches rather than tears) |
| Apprehension | Present in provocative positions | Strongly present; may avoid activities |
| ROM restriction | Significant initially; progressive recovery | May have excessive ROM (multidirectional laxity) |
| Subluxation events | Not expected initially | Frequent; shoulder "slips" with daily activities |
| Force required | Major trauma | Progressively less with each episode |
| RC involvement | Assess for concurrent tear (especially age > 40) | Less common in young recurrent dislocators |
General Presentation (Applicable to All Joints)
- Obvious deformity with altered joint contours
- Immediate loss of function — the joint cannot be actively moved
- Severe pain, rapid swelling, and bruising
- Muscle guarding and protective spasm preventing any movement
- Possible neurovascular compromise distal to the dislocation: numbness, tingling, weakness, diminished or absent pulses, color changes
Assessment Profile
Subjective Presentation
- Chief complaint: Acute: "My shoulder popped out"; "I felt it dislocate and I can't move it"; "I fell on my arm and it looks crooked." Chronic instability: "My shoulder keeps slipping out"; "I'm afraid to raise my arm because it feels loose"; "It pops out when I reach overhead or roll over in bed"
- Pain quality: Acute: intense, sharp, and constant; described as "excruciating" at the moment of injury. Post-reduction: deep aching with sharp provocation in the apprehension position. Chronic: dull aching with episodes of sharp pain during subluxation events; some patients report relatively little pain with recurrent episodes
- Onset: Traumatic: specific mechanism identifiable — fall, collision, forceful movement; patient usually knows the exact moment. Recurrent: episodes of increasing frequency requiring decreasing force; some patients can voluntarily subluxate and reduce their joint
- Aggravating factors: Acute: any movement of the joint. Chronic: positions that replicate the mechanism of dislocation (abduction + ER for anterior GH); overhead reaching; rolling onto the affected side at night; carrying heavy objects; contact sports
- Easing factors: Acute: complete immobilization. Chronic: keeping the arm close to the body; avoiding provocative positions; sling use during vulnerable activities
- Red flags: Neurovascular compromise: numbness in the regimental badge area (axillary nerve), diminished or absent distal pulses, pallor, coolness, or mottled skin in the hand — emergency referral; do not treat. Unreduced dislocation — obvious deformity with inability to move — do not attempt reduction; stabilize and refer for emergency medical management. Seizure-induced dislocation — suspect posterior dislocation; patient may not recognize the dislocation due to postictal confusion.
Observation
- Local inspection: Acute unreduced: obvious deformity — loss of normal joint contour (squared-off deltoid in anterior GH dislocation, with the humeral head visible or palpable anteriorly); rapid swelling and bruising. Post-reduction/chronic: joint contour may appear normal; muscle atrophy of the deltoid (axillary nerve involvement) or RC muscles may be present with chronic instability; generalized joint hypermobility features (skin hyperextensibility, joint hyperflexion) suggest connective tissue disorder.
- Posture: Acute: the joint is held in a fixed position — arm held in slight abduction and ER for anterior GH dislocation; patient cradles the injured limb. Chronic instability: protective posturing with the arm held close to the body; may adopt an internally rotated, adducted shoulder position to minimize anterior translation risk; shoulder height asymmetry may be present.
- Gait: Not directly affected for upper extremity dislocations; arm swing absent or guarded on the affected side. For lower extremity dislocations (hip, knee, ankle) — unable to bear weight with acute dislocation.
Palpation
- Tone: Acute: severe protective muscle guarding surrounding the dislocated joint — muscles are in involuntary spasm to prevent movement; do not attempt to overcome this guarding. Post-reduction/chronic: pectoralis major and subscapularis hypertonicity from protective guarding against anterior translation. Infraspinatus and posterior deltoid may show persistent guarding. Upper trapezius and levator scapulae compensatory hypertonicity.
- Tenderness: Acute: extreme tenderness over the joint; bony landmarks may be displaced or absent from their normal positions (e.g., humeral head not in the glenoid). Post-reduction: anterior GH joint line tenderness (capsular and labral damage); greater tuberosity tenderness (if concurrent RC injury); axillary fold tenderness. Chronic: anterior apprehension with palpation of the anterior capsule; trigger points in compensatory muscles (upper trapezius, pectoralis major, infraspinatus)
- Temperature: Acute: significant warmth and heat over the joint from inflammation and hemarthrosis. Post-reduction: gradually normalizing. Chronic: usually normal
- Tissue quality: Post-reduction: joint may feel "loose" or demonstrate excessive translation on manual testing; capsule may feel lax or redundant. Chronic instability: periarticular muscles may feel fibrotic from repetitive guarding; generalized tissue laxity in patients with connective tissue disorders
Motion Assessment
- AROM: Acute unreduced: no voluntary movement possible — the joint is locked in the dislocated position. Post-reduction: significantly restricted by pain and guarding initially; progressive recovery over weeks. Chronic instability: may have full or excessive ROM (capsular laxity allows excessive translation); apprehension rather than pain may limit end-range motion; patient may demonstrate voluntary subluxation ability.
- PROM / end-feel: Acute unreduced: do not perform PROM — the joint is locked; any attempt at movement produces severe guarding and empty end-feel (patient stops movement due to fear/pain before any tissue resistance is felt). Post-reduction: guarded end-feel in the direction of dislocation (e.g., ER for anterior GH — the patient guards against the apprehension position). Chronic: capsular laxity may produce excessive movement with a soft, mushy end-feel in the direction of instability; sulcus sign test assesses inferior laxity.
- Resisted testing: Acute: not performed (immobilized). Post-reduction: test once initial healing permits; assess for concurrent RC tear — pain and weakness on resisted ER (infraspinatus) or abduction (supraspinatus), particularly in patients over 40. Check deltoid strength (resisted abduction, C5 myotome) to screen for axillary nerve injury. Chronic: may be normal strength; pain may be provoked in provocative positions only.
Special Test Cluster
| Test | Positive Finding | Purpose |
|---|---|---|
| Apprehension test (CMTO) | Apprehension or guarding (not just pain) when the shoulder is passively abducted to 90 degrees and externally rotated — the patient looks alarmed and tries to stop the movement | Confirm anterior GH instability; the defining test for post-dislocation instability; apprehension is the critical finding, not mere pain |
| Relocation test (CMTO) | Apprehension resolves when a posteriorly directed force is applied to the proximal humerus in the apprehension position | Confirm anterior instability — the posterior force prevents anterior translation, demonstrating that the apprehension was caused by instability, not impingement |
| Sulcus sign (CMTO) | Visible indentation (sulcus) between the acromion and humeral head when inferior traction is applied to the arm at the side; graded by distance (Grade 1: < 1 cm; Grade 2: 1-2 cm; Grade 3: > 2 cm) | Confirm inferior GH laxity; positive sulcus sign with the arm in ER suggests rotator interval incompetence and multidirectional instability |
| Load and Shift test (CMTO) | Excessive anterior or posterior translation of the humeral head relative to the glenoid when an axial load is applied with translational force | Quantify the degree of GH translation in each direction — anterior, posterior, inferior; compare bilateral; graded by percentage of humeral head translation |
| Anterior drawer test (shoulder) (supplementary) | Excessive anterior humeral head translation with forward force applied to the proximal humerus while stabilizing the scapula | Confirm anterior laxity — supplementary to Apprehension + Relocation when quantifying translation |
| Jerk Test (supplementary) | Patient seated, arm medially rotated and forward flexed to 90 degrees; examiner axially loads the humerus and horizontally adducts the arm; a sudden jerk or clunk as the humeral head slides off the posterior glenoid indicates posterior instability; a second jerk on return to 90 degrees as the head reduces | Confirm posterior GH instability — addresses the posterior instability component that the anterior-focused Apprehension/Relocation cluster does not assess; also indicates posteroinferior labral tear |
Neurovascular screening is mandatory after any dislocation. Test axillary nerve function: sensation over the regimental badge area (lateral deltoid) and deltoid strength (resisted abduction). Check distal pulses (radial artery), hand color, temperature, and capillary refill. Document findings pre- and post-treatment.
Differential Assessment
| Condition | Key Distinguishing Feature |
|---|---|
| Fracture | Bony deformity and point tenderness directly over bone; crepitus on palpation; inability to bear weight; confirmed by imaging. Fracture-dislocation combinations are common — always consider concurrent fracture with any dislocation. |
| Rotator cuff tear (acute massive) | Sudden inability to elevate the arm after a traumatic event (mimics dislocation); normal joint contour on observation (no deformity); positive Drop Arm test; PROM markedly exceeds AROM; imaging differentiates |
| Labral tear without dislocation | Deep shoulder pain with mechanical catching; positive O'Brien's or Crank test; no history of frank dislocation or visible deformity; apprehension may be present but without the acute dislocation event |
| Acromioclavicular separation | Deformity at the AC joint (step deformity), not the GH joint; positive cross-body adduction; piano key sign; mechanism is typically a fall directly onto the shoulder, not forced ER |
| Brachial plexus injury (stinger) | Sudden burning pain and weakness radiating into the arm after a blow to the head/neck (common in football); symptoms are transient (seconds to minutes); no joint deformity; full ROM once symptoms resolve |
CMTO Exam Relevance
- CMTO Appendix category A1 (MSK conditions) — dislocation and instability are commonly tested
- Essential tests: Apprehension Test, Relocation Test, Sulcus Sign, Load and Shift — know technique, positioning, and interpretation for all four
- Key principle: apprehension (not just pain) is the critical positive finding on the Apprehension test — this distinction is frequently tested on MCQ
- Reduction must only be performed by a qualified medical professional — never by a massage therapist
- Neurovascular assessment is mandatory before and after any treatment near a previously dislocated joint — axillary nerve (regimental badge sensation, deltoid strength) and distal pulses
- Understand recurrence risk by age: < 20 = approximately 90%; > 40 = approximately 10% — this informs treatment planning and prognosis discussions
- Know the Bankart-Hill-Sachs bipolar lesion pattern and the circle concept of instability
- Posterior dislocation mechanism (seizure/electrocution) is frequently tested because it is commonly missed clinically (the arm is held in IR and adduction, and standard AP radiographs may appear near-normal)
Massage Therapy Considerations
- Primary therapeutic target: the compensatory muscle guarding pattern that develops post-reduction and with chronic instability — pectoralis major, subscapularis, and infraspinatus hypertonicity from protecting the unstable joint. MT cannot restore capsular or labral integrity but can manage the muscular consequences that reduce functional ROM and perpetuate abnormal movement patterns.
- Sequencing logic: establish that the joint is reduced and stable before any treatment → release global compensatory guarding (cervicothoracic, periscapular) → carefully address specific periarticular muscles → gentle ROM exploration within safe limits. Always treat the surrounding environment before approaching the injured joint.
- Safety / contraindications: Acute unreduced dislocations are strictly contraindicated — do not treat; stabilize and refer. Recent dislocations in the immobilization phase — treat only surrounding muscles with the sling in place; do not mobilize the affected joint. Stretching and end-range ROM techniques are contraindicated for joints with dislocation history — this risks further stretching already lax capsular structures and precipitating redislocation. Neurovascular compromise (numbness, weakness, absent distal pulses, color changes) — immediate emergency medical referral; do not treat. Post-surgical stabilization (Bankart repair, capsulorrhaphy): follow the surgeon's protocol strictly; premature mobilization compromises the repair.
- Heat/cold guidance: Ice post-treatment for acute/subacute stages (reduce reactive inflammation). Moist heat before treatment for chronic instability to improve tissue extensibility of the guarding muscles. Avoid aggressive heat to a joint with active effusion.
Treatment Plan Foundation
Clinical Goals
- Reduce periarticular muscle guarding (pectoralis major, subscapularis, infraspinatus, upper trapezius) to improve functional ROM within safe limits
- Address compensatory hypertonicity in cervicothoracic and periscapular muscles
- Support dynamic stabilization by releasing muscles that interfere with RC and scapular stabilizer function
- Maintain available ROM without challenging capsular integrity in the direction of instability
Position
- Side-lying (affected side up) preferred — allows controlled arm positioning, access to posterior cuff and periscapular muscles, and avoids placing the joint in vulnerable positions
- Supine for anterior shoulder access (pectoralis major, anterior deltoid) — keep the arm supported at the side; avoid end-range ER for anterior dislocation history
- Prone for thoracic spine and posterior scapular work if the patient is comfortable
Session Sequence
- General effleurage to the cervicothoracic region — assess global guarding patterns; the entire shoulder girdle complex becomes hypertonic to compensate for lost passive stability
- Upper trapezius and levator scapulae release — reduce compensatory shoulder hiking; these muscles chronically elevate to provide dynamic stability when the capsule is lax
- Thoracic paraspinal release — restore thoracic extension and improve scapulothoracic positioning; address the postural foundation
- Pectoralis major release — reduce anterior guarding that restricts ER and pulls the humeral head forward; gentle longitudinal stripping and myofascial release [supine, arm supported at side]
- Infraspinatus and teres minor release — myofascial release and gentle trigger point work; these muscles become hypertonic from chronic co-contraction to resist anterior translation [side-lying]
- Subscapularis release via axillary fold access — gentle sustained compression; subscapularis guarding is intense after anterior dislocation and limits ER [requires verbal notification]
- Deltoid work — gentle effleurage and myofascial release; assess for atrophy (axillary nerve involvement); do not apply deep pressure if axillary nerve injury is suspected
- Reassessment — gentle active ROM within safe limits; compare to pre-treatment; note changes in guarding and available range; do not push into end-range positions that stress the unstable direction
Adjunct Modalities
- Hydrotherapy: Ice post-treatment for subacute stages. Moist heat before treatment for chronic instability to reduce muscle guarding and improve tissue extensibility. Avoid heat to a joint with active effusion.
- Joint mobilization: Contraindicated in the direction of instability (no anterior glide for anterior instability). Gentle Grade I-II mobilization in the opposite direction may be appropriate (posterior and inferior GH glides for anterior instability — these improve capsular mobility without stressing the damaged structures). Scapulothoracic mobilization is safe and beneficial for all instability presentations. Progress only after physician clearance.
- Remedial exercise (on-table): Isometric RC strengthening — isometric ER at 0 degrees abduction (engages infraspinatus and teres minor as dynamic anterior stabilizers without provocative positioning); isometric IR (subscapularis co-contraction for joint centering). Scapular setting (retraction and depression) to facilitate periscapular stabilizers. Avoid eccentric or end-range loading until the capsule has healed or been surgically repaired.
Exam Station Notes
- Verbalize that neurovascular assessment is performed before and after treatment — check regimental badge sensation (axillary nerve) and distal pulses
- Demonstrate that you understand the direction of instability and how it dictates which positions and techniques to avoid (e.g., "This is an anterior instability, so I will avoid end-range ER and anterior humeral translation")
- Show bilateral comparison of ROM and sulcus sign — verbalize findings
- State the treatment rationale: "I am addressing the compensatory muscle guarding around the unstable joint, not attempting to restore capsular integrity"
Verbal Notes
- Axillary fold access for subscapularis: "I'm going to work on a muscle on the front of your shoulder blade through the area near your armpit — please let me know if you're uncomfortable"
- Instability awareness: "Because of your shoulder injury history, I'm going to keep your arm in safe positions throughout the treatment. If at any point you feel like your shoulder is shifting, becoming unstable, or feels like it might pop out, tell me immediately and I'll change the position."
- Post-treatment: advise that the shoulder may feel achy for 24-48 hours; continue using the sling if prescribed; avoid sudden forceful movements; ice if discomfort increases
Self-Care
- Isometric rotator cuff strengthening — ER and IR holds against a wall or doorframe at 0 degrees abduction, 6-second contractions, 10 repetitions — builds dynamic stabilizers without stressing the lax capsule
- Scapular retraction and depression exercises — wall push-up plus (serratus anterior), prone Y-T-W (lower trapezius) — improves scapulothoracic stability to compensate for capsular laxity
- Avoid sleeping on the affected side or with the arm overhead; use a pillow to keep the arm supported at the side
- Activity modification: avoid contact sports until medically cleared; avoid end-range positions in the direction of instability; use caution with overhead reaching and lifting
Key Takeaways
- Anterior glenohumeral dislocation accounts for 95% of shoulder dislocations; the Bankart lesion (anteroinferior labral avulsion) and Hill-Sachs lesion (posterolateral humeral head compression fracture) are the characteristic bipolar injury pattern
- Recurrence risk is strongly age-dependent: first dislocation under age 20 carries approximately 90% recurrence risk; over age 40, approximately 10% — age at first dislocation is the strongest predictor of chronic instability
- Each dislocation event further stretches the capsule and deepens osseous defects, progressively reducing the force required for subsequent episodes
- Acute unreduced dislocations and neurovascular compromise are strict contraindications — stabilize and refer; reduction must only be performed by a qualified medical professional
- Apprehension (not just pain) is the critical positive finding on the Apprehension test — this distinction separates instability from impingement and is frequently tested on CMTO exams
- The Sulcus sign grades inferior laxity; a positive sulcus sign with the arm in ER suggests rotator interval incompetence and multidirectional instability
- Post-stabilization MT addresses compensatory muscle guarding; stretching and end-range ROM techniques are contraindicated for joints with dislocation history to avoid further stretching lax capsular structures