Glenohumeral dislocations

1. High-Yield Summary

Glenohumeral dislocation represents the most common major joint dislocation in human anatomy, accounting for approximately 50% of all joint dislocations with an annual incidence of 17 to 24 per 100,000 person-years:

• Epidemiology & Directional Spectrum: Anterior dislocations comprise 95% to 97% of all presentations (predominantly subcoracoid), followed by posterior dislocations (2% to 4%, classically linked to seizures, electrocution, or high-energy axial loading), and inferior dislocations (luxatio erecta, less than 0.5%, presenting with the arm locked in fixed hyperabduction overhead).
• Age-Dependent Recurrence Kinetics: The patient’s age at the index dislocation represents the single most powerful prognostic indicator of recurrence. Nonoperative management in patients younger than 20 years results in an 80% to 94% redislocation rate, whereas patients older than 40 years experience a recurrence rate below 10% to 15% but face a 30% to 70% risk of concomitant rotator cuff tearing (subscapularis, supraspinatus) and greater tuberosity fractures.
• Pathomechanics & Bipolar Bone Loss: Glenohumeral stability relies on the concavity-compression mechanism, labral deepening, and the inferior glenohumeral ligament complex (IGHLC). Traumatic anterior avulsion produces anteroinferior capsulolabral disruption (Bankart, ALPSA, Perthes, GLAD, or HAGL) and frequent bipolar osseous defects: anterior glenoid rim fractures (bony Bankart) and engaging posterolateral humeral head impaction fractures (Hill-Sachs lesions).
• The Glenoid Track Paradigm: Assessment of glenohumeral instability requires quantifying bipolar bone loss using the glenoid track concept. A Hill-Sachs lesion is classified as “on-track” if it remains contained within the contact zone of the glenoid during physiological abduction and external rotation; an “off-track” lesion extends medial to the glenoid track, engaging the anterior glenoid margin and mandating bony reconstruction (open Latarjet) or adjunctive soft-tissue fill (remplissage).
• Evidence-Based Surgical Thresholds: Arthroscopic Bankart repair with or without capsular plication is indicated for young active individuals with isolated capsulolabral tears, glenoid bone loss below 13.5%, and on-track Hill-Sachs lesions. Open Latarjet coracoid transfer is strictly indicated for subcritical bone loss exceeding 13.5% to 15% in collision athletes, critical bone loss exceeding 20% to 25% in any patient, engaging off-track Hill-Sachs defects unsuitable for remplissage, or an Instability Severity Index Score (ISIS) greater than 6.

2. Anatomy

Bony Architecture & Articular Geometry

The glenohumeral joint is an inherently unstable ball-and-socket articulation characterized by extreme osseous disproportion, often likened to a golf ball sitting on a golf tee. The spherical humeral head has a surface area three to four times greater than the shallow, pear-shaped glenoid fossa, such that only 25% to 30% of the humeral head articulates with the glenoid cartilage at any given position in the range of motion. The normal glenoid exhibits approximately 2° to 8° of retroversion and approximately 5° of superior tilt relative to the scapular blade. The glenoid rim is deepened by approximately 50% (increasing from approximately 2.5 mm to 5 to 9 mm in depth) by the surrounding triangular fibrocartilaginous labrum, which doubles the effective depth and provides a critical “chock-block” concavity-compression mechanical barrier against translation.

Static Capsuloligamentous Stabilizers

Static restraint is provided by the joint capsule, glenoid labrum, negative intra-articular pressure, and discrete glenohumeral ligaments:

• Glenoid Labrum: Anchors the fibrous capsule to the bony rim and provides the anatomical foundation for the concavity-compression effect by deepening the glenoid socket and serving as the insertion platform for the capsuloligamentous constraints.
• Superior Glenohumeral Ligament (SGHL): Originates from the supraglenoid tubercle and superior labrum; inserts into the fovea capitis just superior to the lesser tuberosity. Serves as the primary static restraint against inferior humeral head translation with the arm adducted at the side (0° abduction) and resists posterior translation in adduction.
• Middle Glenohumeral Ligament (MGHL): Originates from the supraglenoid tubercle and anterosuperior labrum; courses obliquely across the subscapularis tendon to insert on the lesser tuberosity. It is the most anatomically variable ligament (absent in up to 30% of individuals, or cord-like in a Buford complex). Resists anterior translation with the arm abducted to 45° in neutral to external rotation.
• Inferior Glenohumeral Ligament Complex (IGHLC): The most critical static stabilizer of the shoulder, functioning like a hammock suspended between the anteroinferior and posteroinferior glenoid rim and anatomical neck of the humerus. Composed of an Anterior Band (AB-IGHL), a Posterior Band (PB-IGHL), and an interposed Axillary Pouch. The AB-IGHL becomes taut in 90° of abduction and maximal external rotation, serving as the primary barrier against traumatic anterior dislocation. The PB-IGHL becomes taut in 90° of abduction and internal rotation, resisting posterior subluxation.
• Coracohumeral Ligament (CHL) & Rotator Interval: Spans from the lateral base of the coracoid process to the greater and lesser tuberosities, bridging the interval between the supraspinatus and subscapularis. Resists inferior and posterior translation in the adducted position.
• Negative Intra-Articular Pressure: The sealed, fluid-filled glenohumeral joint maintains a resting hydrostatic vacuum of approximately -4 mmHg, generating a suction-cup effect that resists inferior displacement in the resting arm.

Dynamic Stabilizers & Force Couples

Dynamic stabilization is mediated by balanced muscular activation that compresses the humeral head directly into the center of the glenoid concavity:

• Rotator Cuff Musculature: The subscapularis anteriorly, supraspinatus superiorly, and infraspinatus and teres minor posteriorly form a balanced coronal and transverse force couple. Active contraction generates concavity-compression force vectors that seat the humeral head firmly against the glenoid throughout dynamic elevation and rotation.
• Long Head of the Biceps Brachii (LHB): Acts as an active humeral head depressor and anterior stabilizer, particularly in abduction and external rotation, by increasing torsional stiffness and dampening anterior translation.
• Periscapular Musculature: The serratus anterior, trapezius (upper, middle, and lower), rhomboids, and levator scapulae coordinate scapulothoracic rhythm, positioning the glenoid face directly beneath the instantaneous force vector of the humeral head during overhead athletic maneuvers.

Internervous Planes & Surgical Corridors

Surgical access to the glenohumeral joint relies on precise anatomical intervals:

• Anterior Deltopectoral Approach: Utilizes the classic internervous plane between the deltoid muscle (innervated by the axillary nerve, C5-C6) and the pectoralis major muscle (innervated by the lateral and medial pectoral nerves, C5-T1). The cephalic vein marks the intermuscular boundary and is typically retracted laterally with the deltoid to preserve its deltoid tributaries.
• Subscapularis Management: Deep anterior exposure is achieved either via a horizontal subscapularis muscle-splitting approach in its upper two-thirds or a formal subscapularis tenotomy/peel. The upper two-thirds split is safer because the lower subscapular nerve enters the inferior third of the muscle belly approximately 1.5 cm medial to its insertion.
• Posterior Infraspinatus-Teres Minor Approach: Operates through the internervous plane between the infraspinatus (suprascapular nerve, C5-C6) and the teres minor (axillary nerve, C5-C6). Dissection must remain strictly within this interval, avoiding the lower border of the teres minor where the axillary nerve exits the quadrangular space.

Neurovascular Danger Zones

Major peripheral nerves and vascular conduits traverse immediately adjacent to the glenohumeral capsule, presenting critical surgical danger zones:

• Axillary Nerve (C5-C6): Courses across the anterior-inferior border of the subscapularis muscle, wraps tightly beneath the inferior capsule, and passes through the quadrangular space (bounded by teres minor superiorly, teres major inferiorly, long head of triceps medially, and humeral shaft laterally). At the 6 o’clock position on the glenoid rim, the axillary nerve lies a mere 3 to 5 mm from the capsule. It is intensely vulnerable during inferior capsulotomy, anteroinferior suture anchor placement at the 5:30 to 6:00 position, and during the subscapularis split or coracoid transfer in the Latarjet procedure.
• Musculocutaneous Nerve (C5-C7): Penetrates the deep medial surface of the coracobrachialis muscle. The anatomical distance from the tip of the coracoid process to the nerve entry point averages 5 to 8 cm, but can be as short as 2.5 cm in variant anatomy. Excessive inferomedial retraction of the conjoint tendon during exposure or dissection beyond 3 cm distal to the coracoid tip carries high risk of traction neuropraxia or laceration.
• Suprascapular Nerve (C5-C6): Travels through the suprascapular notch beneath the superior transverse scapular ligament to supply the supraspinatus, then winds around the spinoglenoid notch into the infraspinatus fossa. The nerve is located approximately 1.5 to 2.0 cm medial to the posterior glenoid rim. It is endangered by overly medial drill hole placement, retractor placement deep into the spinoglenoid notch, or posterior capsulotomy.
• Axillary Artery & Brachial Plexus: Situated immediately medial to the conjoint tendon and deep to the pectoralis minor. In elderly patients with arteriosclerosis, aggressive closed reduction traction maneuvers or over-retraction can result in catastrophic intimal tearing, thrombosis, or pseudoaneurysm formation of the axillary artery.

3. Pathogenesis

Mechanisms of Failure & Biomechanical Force Vectors

The vector of traumatic displacement dictates the resulting mechanical failure pattern:

• Anterior Dislocation (95% to 97%): The classic vector involves forceful abduction, external rotation, and extension (e.g., a football tackle, an overhead thrower blocked in late cocking phase, or a fall onto an outstretched hand with the arm extended). This posture forces the greater tuberosity against the acromion, levering the spherical humeral head anteriorly and inferiorly over the anterior glenoid rim. The resulting shear stresses tear the anteroinferior labrum and avulse the anterior band of the IGHLC.
• Posterior Dislocation (2% to 4%): Caused by severe axial loading applied to an arm positioned in flexion, adduction, and internal rotation (e.g., head-on motor vehicle collision with hands on the steering wheel, or a fall on an internally rotated hand). Alternatively, violent involuntary muscular contractions during generalized epileptic seizures, high-voltage electrocution, or electroconvulsive therapy drive posterior dislocation because the massive internal rotators (latissimus dorsi, pectoralis major, subscapularis) mechanically overpower the smaller external rotators (infraspinatus, teres minor).
• Inferior Dislocation / Luxatio Erecta (<0.5%): Results from severe hyperabduction forces that impinge the proximal humeral neck against the unyielding acromion process, creating a fulcrum that levers the humeral head downward through the weak inferior capsule. The humeral shaft remains locked in vertical alignment pointing upward, with the arm elevated 110° to 160° overhead and the elbow flexed.

Capsulolabral Disruption Spectrum

Traumatic anterior translation produces a distinct spectrum of capsulolabral lesions:

• Classic Bankart Lesion: Complete avulsion of the anteroinferior labrum and attached anterior band of the IGHL from the glenoid articular cartilage rim with tearing of the adjacent periosteal sleeve.
• ALPSA (Anterior Labroligamentous Periosteal Sleeve Avulsion): The labroligamentous complex detaches from the glenoid rim but the anterior scapular periosteum remains intact, allowing the labrum to peel medially and roll downward along the anterior glenoid neck. It heals in an anatomically medialized, incompetent position, leading to persistent joint instability.
• Perthes Lesion: An incomplete avulsion where the anteroinferior labrum is stripped from the glenoid rim, but the periosteum remains intact without medial displacement. The labrum lies in normal anatomical position, making detection difficult on non-contrast imaging.
• GLAD (Glenolabral Articular Disruption): A superficial tear of the anterior-inferior labrum combined with an adjacent chondral shear fracture of the anterior articular cartilage of the glenoid, typically caused by impaction during subluxation without gross dislocation.
• HAGL (Humeral Avulsion of the Glenohumeral Ligament): Traumatic avulsion of the inferior glenohumeral ligament from its anatomical insertion on the humeral neck rather than the glenoid rim. Can present as anterior HAGL, posterior HAGL (PHAGL), or bony HAGL (bony avulsion flake from humerus).
• Kim Lesion: Incomplete, concealed avulsion of the posteroinferior labrum beneath a seemingly intact superficial chondrolabral junction, leading to posterior and bidirectional instability.
• Reverse Bankart Lesion: Detachment of the posteroinferior labrum from the posterior glenoid rim resulting from posterior dislocation.

Bipolar Osseous Pathology & Glenoid Track Mechanics

Bipolar osseous defects interact synergistically to destabilize the glenohumeral joint:

• Bony Bankart Lesion: Fracture or progressive attritional erosion of the anteroinferior glenoid rim. Glenoid bone loss transforms the normal pear-shaped glenoid into an “inverted pear” morphology, severely diminishing the concavity-compression surface area.
• Hill-Sachs Lesion: An impaction compression fracture of the posterolateral aspect of the humeral head, created when the soft cancellous bone of the head strikes the hard cortical margin of the anterior glenoid rim during anterior dislocation.
• Reverse Hill-Sachs (McLaughlin) Lesion: An impaction fracture of the anteromedial humeral head caused by collision with the posterior glenoid rim during posterior dislocation.
• The Glenoid Track Concept (Yamamoto & Itoi): During shoulder elevation, the contact area between the glenoid and the humeral head shifts dynamically from the inferomedial margin to the superolateral aspect of the articular surface, tracing a zone termed the “glenoid track.” The width of this track in an intact shoulder measures approximately 84% of the glenoid diameter (D). When anterior glenoid bone loss (d) occurs, the true track width narrows to: Glenoid Track = 0.84D – d. The Hill-Sachs interval (HSI) is calculated as the width of the Hill-Sachs defect plus the intact bone bridge between the lateral margin of the defect and the rotator cuff footprint. If HSI is less than or equal to the glenoid track, the lesion is “on-track” (contained within the articular contact area, will not engage). If HSI exceeds the glenoid track, the lesion is “off-track” (the defect over-rides the anterior glenoid rim during physiological abduction and external rotation, producing engagement, mechanical levering, and recurrent dislocation).

4. Natural History

Demographic Distribution & Bimodal Epidemiology

The incidence of glenohumeral dislocations follows a classic bimodal distribution across human lifespans. The primary peak occurs in young males aged 15 to 29 years, driven by high-energy contact sports, competitive collision athletics, and vehicular trauma. In this demographic, males outnumber females by approximately 3:1. The secondary peak emerges in elderly women aged 60 to 80 years, typically resulting from low-energy mechanical falls from standing height onto an outstretched hand, where osteoporotic bone fragility and pre-existing degenerative rotator cuff disease predispose to capsular failure.

Age-Dependent Recurrence Kinetics

The age of the patient at the time of the primary dislocation is the single most decisive factor governing long-term joint stability:

• Age Under 20 Years: Recurrence rates after nonoperative management exceed 80% to 94%. Active epiphyseal metabolism, higher baseline capsular compliance, vigorous return to collision sports, and incomplete biological healing of the Bankart lesion account for this near-universal failure.
• Age 20 to 30 Years: Recurrence rates range from 50% to 70% with conservative care.
• Age 30 to 40 Years: Recurrence rates drop to 20% to 40%.
• Age Over 40 Years: Recurrence rates plummet to below 10% to 15%. Progressive age-related capsular stiffening and reduced participation in high-risk collision sports protect against recurrent dislocation.

Concomitant Pathology in the Aging Shoulder

While redislocation is uncommon in patients older than 40 years, the incidence of concomitant structural soft-tissue and nerve injury escalates dramatically. Traumatic rotator cuff tears (specifically subscapularis and supraspinatus full-thickness avulsions) occur in 30% to 70% of dislocators aged 40 to 60 years, and exceed 80% to 100% in patients older than 60 years. Greater tuberosity fractures occur in 15% to 35% of older dislocators. Axillary nerve neuropraxia occurs in 5% to 10% of presentations, often manifesting as combined loss of active abduction (deltoid and supraspinatus failure) termed the “terrible triad of the shoulder” (dislocation, rotator cuff tear, and neurological injury).

Post-Traumatic Instability Arthropathy

Recurrent glenohumeral instability inexorably damages articular cartilage. Post-traumatic osteoarthritis (classified using the Samilson-Prieto system: Mild = inferior osteophyte <3 mm; Moderate = osteophyte 3 to 7 mm with slight joint narrowing; Severe = osteophyte >7 mm with joint space obliteration) develops in 20% to 50% of patients within 10 to 25 years following the index dislocation. The severity of arthropathy correlates directly with the total number of dislocation episodes, the presence of bipolar osseous defects, older age at the primary dislocation, and previous non-anatomical stabilization procedures (such as the Putti-Platt or Magnuson-Stack operations) that permanently tether external rotation and force posterior humeral head decentration.

5. Clinical Presentation

History

Clinical evaluation begins with an exhaustive interrogation of the injury event and functional impairment:

• Trauma Vector & Arm Positioning: Determine the exact arm posture at impact (overhead/external rotation vs adducted/internal rotation vs axial load), and distinguish high-energy collision from trivial movement (e.g., rolling over in bed, which indicates profound bone loss or multidirectional hyperlaxity).
• Chronicity & Episode Frequency: Differentiate a virgin dislocation from recurrent instability; document the lifetime number of dislocations, subluxations, and the ease of reduction (spontaneous, patient self-reduced, or requiring emergency department procedural sedation).
• Neurological Symptoms: Specifically inquire about transient “dead arm” sensations, paresthesias, or profound weakness along the lateral shoulder following the episode.
• Systemic Collagen Phenotype: Screen for generalized ligamentous hyperlaxity (Beighton score criteria, family history, multidirectional instability) and prior history of seizures or electrical shock injuries.

Physical Exam

Examination incorporates systematic inspection, neurovascular assessment, and validated provocative maneuvers:

• Visual Inspection (Anterior): The shoulder exhibits loss of normal rounded deltoid contour (“squared-off” appearance), prominent acromion, and a palpable anterior fullness in the subcoracoid space. The patient holds the injured arm in slight abduction and external rotation, guarding against internal rotation.
• Visual Inspection (Posterior): The anterior shoulder appears flattened with a prominent coracoid process, and a fullness is palpable posteriorly beneath the acromion. The arm is locked in adduction and internal rotation; external rotation beyond neutral is completely blocked.
• Visual Inspection (Luxatio Erecta): The arm is held fixed in severe abduction (110° to 160°) above the head with the elbow flexed and the hand resting on or behind the head. The humeral head is palpable in the axilla along the lateral thoracic wall.
• Anterior Apprehension Test: Patient supine; arm abducted 90°, elbow flexed 90°, gentle external rotation applied. Positive finding: Patient expresses distress, fear of impending subluxation, or reflexively contracts pectoralis/deltoid [Sensitivity 68% to 88%, Specificity 90% to 98%].
• Jobe Relocation Test: Following positive apprehension, examiner applies a posterior-directed force to the anterior humeral head. Positive finding: Immediate relief of apprehension and pain, allowing further external rotation [Sensitivity 81% to 85%, Specificity 90% to 92%].
• Surprise / Anterior Release Test: Following the relocation test, posterior stabilizing pressure is abruptly released. Positive finding: Sudden return of apprehension and pain [Sensitivity 64% to 92%, Specificity 89% to 98%].
• Load-and-Shift Test: Patient seated; humeral head loaded into the glenoid fossa and translated anteriorly and posteriorly. Graded as Grade 0 (normal, <25%), Grade I (translation to the glenoid rim, 25% to 50%), Grade II (translation over the rim with spontaneous reduction upon release, >50%), Grade III (dislocation over rim without spontaneous reduction) [Sensitivity 65% to 80%, Specificity 90% to 95%].
• Sulcus Sign: Downward axial traction applied to the elbow with the arm adducted at the side (0° abduction). Inferior translation measured from lateral acromion: Grade 1 (<1 cm), Grade 2 (1 to 2 cm), Grade 3 (>2 cm). Persistence in 30° external rotation confirms rotator interval and coracohumeral ligament deficiency [Sensitivity 72% to 85%, Specificity 85% to 93%].
• Jerk Test: Arm flexed 90° and internally rotated; examiner applies axial compressive load while horizontally adducting the arm across the chest. Positive finding: Sudden sharp pain with a palpable “clunk” as the humeral head subluxates posteriorly [Sensitivity 73% to 90%, Specificity 98%].
• Kim Test: Arm abducted 90° and elevated 45° with simultaneous axial compression, while examiner applies an upward and backward force to the proximal arm. Positive finding: Sudden sharp posteroinferior shoulder pain [Sensitivity 80% to 97%, Specificity 94% to 97%]. Combining the Jerk and Kim tests yields 97% sensitivity for posteroinferior labral pathology.
• Neurovascular Examination: Meticulous pre- and post-reduction documentation of axillary nerve sensation over the lateral deltoid “regimental badge” area and deltoid motor tone. Musculocutaneous, radial, median, and ulnar nerves, along with radial and brachial pulses, must be verified to exclude axillary artery injury.

6. Imaging and Diagnostic Studies

Essential Radiographic Projections

Evaluation of acute shoulder trauma mandates an orthogonal trauma radiographic series:

• True AP of the Glenohumeral Joint (Grashey View): Beam angled 35° to 45° obliquely towards the scapular plane, perpendicular to the glenoid face. Profiles the joint space without overlapping the humeral head on the glenoid rim, identifying joint space narrowing, glenoid rim avulsion fractures, and vertical displacement.
• Scapular Y View (Trans-scapular Lateral): Beam aligned parallel to the scapular spine. The scapular body, spine, and coracoid form a “Y.” Clearly displays anterior displacement beneath the coracoid process (subcoracoid) or posterior displacement beneath the acromion.
• Axillary Lateral View (Mandatory Gold Standard): Absolutely essential to establish glenohumeral congruency and definitively distinguish anterior from posterior dislocation. Demonstrates anterior versus posterior subluxation and profiles glenoid rim fractures. If severe pain precludes abduction, a Velpeau Axillary View (patient seated, leaning backward 30° over the film cassette) is obtained.
• West Point View: Prone axillary view with beam angled 25° anteriorly and 25° medially; provides a tangential profile of the anteroinferior glenoid rim, identifying bony Bankart fractures.
• Stryker Notch View: Patient supine with the hand placed on top of the head; beam angled 10° cephalad centered over the coracoid process. Profiles the posterolateral margin of the humeral head, clearly delineating the depth and extent of a Hill-Sachs lesion.

Quantitative Computed Tomography & 3D Reconstruction

Thin-slice (<=1 mm) CT with 3D reconstructions and digital subtraction of the humeral head represents the gold standard for measuring glenoid and humeral bone loss:

• Glenoid Bone Loss Quantification (Best-Fit Circle / Pico Method): An en-face sagittal 3D view of the glenoid is generated. A perfect circle is fitted to the lower two-thirds (inferior pear) of the glenoid margin using the uninjured contralateral shoulder or the intact posteroinferior rim as reference. The percentage of missing anteroinferior bone area relative to the total circle area is calculated: % Bone Loss = (Defect Area / Total Circle Area) * 100.
• Preoperative Bone Loss Thresholds: Glenoid bone loss exceeding 13.5% to 15% is categorized as subcritical, whereas loss exceeding 20% to 25% represents critical bone loss requiring bony augmentation.

Magnetic Resonance Imaging & MR Arthrography (MRA)

MRI provides definitive soft-tissue characterization:

• MR Arthrography (MRA): Intra-articular injection of diluted gadolinium distends the joint capsule, yielding 95% to 98% sensitivity and 90% to 95% specificity for labral tears. MRA readily distinguishes classic Bankart tears from medialized ALPSA lesions, non-retracted Perthes lesions, GLAD lesions, and HAGL avulsions (demonstrated by fluid extravasation forming a “J-sign” at the humeral neck).
• Rotator Cuff & Older Patient Imaging: In patients older than 40 years presenting with acute dislocation, non-contrast MRI is mandatory within 1 to 2 weeks post-reduction to detect full-thickness tears of the subscapularis and supraspinatus tendons.
• Hill-Sachs Interval (HSI): Axial T2-weighted MRI or CT precisely measures the depth and width of the Hill-Sachs impaction and determines the distance from the medial border of the defect to the rotator cuff insertion (bone bridge).

7. Classification

Management is guided by validated classification schemes that stratify instability based on etiology, directional displacement, recurrence risk, and bipolar osseous geometry:

8. Treatment

Reduction Techniques

Acute closed reduction should be performed expeditiously following radiographic confirmation of dislocation and documentation of neurovascular status. Gentle, low-force techniques relying on muscular relaxation are strongly favored over high-traction, violent leverage maneuvers:

• Hennepin (External Rotation) Technique: Patient supine or seated upright; elbow flexed to 90° with arm adducted against the torso. The examiner slowly and gently guides the forearm into external rotation over 5 to 10 minutes. Spontaneous reduction typically occurs at 70° to 80° of external rotation as the subscapularis relaxes and clears the humeral head. Success rate exceeds 85% to 90% with minimal pain and no requirement for conscious sedation.
• Cunningham Technique: Patient seated upright with arm adducted; examiner kneels adjacent and places patient’s wrist on examiner’s shoulder. Examiner massages the trapezius, deltoid, and biceps muscles sequentially to facilitate active relaxation. Spontaneous reduction occurs within minutes without traction or sedation.
• Stimson Technique: Patient prone on stretcher with dislocated arm hanging vertically over the edge. A 5 to 15 lb (2.5 to 7 kg) weight is suspended from the wrist. Gravity-assisted longitudinal traction relaxes the periscapular and rotator cuff musculature, resulting in gentle spontaneous reduction over 15 to 20 minutes.
• Milch Technique: Patient supine; examiner slowly abducts the arm overhead into full forward flexion and external rotation while applying gentle axial traction. The examiner’s thumb is placed in the axilla to guide the humeral head over the glenoid rim.
• FARES (Fast, Reliable, and Safe) Technique: Patient supine; examiner applies gentle axial longitudinal traction to the wrist with the arm extended. The examiner oscillates the arm vertically with short, continuous sinusoidal movements (amplitude ∼5 cm, frequency 2-3 Hz) while gradually abducting the arm to 90° and externally rotating. High success rate (>95%) with significantly less pain and shorter reduction times than Kocher or Hippocratic methods.
• Historical Reduction Pitfall: The Hippocratic method (foot placed in axilla as a fulcrum) and Kocher leverage technique are condemned due to catastrophic risks of humeral shaft/neck fracture, axillary nerve transection, and axillary artery rupture.
• Posterior Dislocation Reduction: Requires conscious sedation. Gentle axial longitudinal traction is applied along the adducted, internally rotated arm, while an assistant applies direct anterior pressure to the posterior humeral head. Once the head disengages from the posterior glenoid rim, the arm is slowly externally rotated into neutral.
• Luxatio Erecta Reduction: Upward traction is applied along the line of the fully abducted humerus with an assistant providing counter-traction downward across the torso. Once the humeral head disengages from the inferior glenoid neck, the arm is gently swung into adduction against the chest wall.

Medical / Nonoperative Management

Nonoperative management is the standard of care for first-time dislocations in low-demand or elderly patients, and in young patients without critical bone loss choosing conservative care:

• Immobilization Parameters: Sling immobilization is prescribed strictly for comfort for 1 to 2 weeks. High-level randomized controlled trials confirm that prolonged immobilization exceeding 3 to 4 weeks does not decrease redislocation rates and induces significant arthrofibrosis and muscular atrophy.
• Sling Positioning (Internal vs External Rotation): Traditional internal rotation slings remain standard practice. Although external rotation bracing (10° to 30°) theoretically coapts the Bankart lesion to the glenoid neck by tensioning the subscapularis, large multicenter trials have demonstrated poor patient compliance and no statistically significant long-term reduction in recurrence rates over conventional internal rotation slings.

Structured 4-Phase Rehabilitation Protocol:

• Phase I (Weeks 0-2: Acute Protection): Sling worn for comfort; gentle pendulum exercises, active elbow, wrist, and hand range of motion; scapular retraction and depression exercises. Avoid abduction >90° and external rotation >0°.
• Phase II (Weeks 2-6: Range of Motion & Early Activation): Discontinue sling; initiate active-assisted and active range of motion in the plane of the scapula. Begin submaximal isometric strengthening for deltoid and rotator cuff. Gradually advance external rotation to 30° at 45° abduction.
• Phase III (Weeks 6-12: Dynamic Strengthening): Progressive resistive exercises using elastic bands and free weights targeting rotator cuff (external rotators, subscapularis) and periscapular stabilizers (serratus anterior, lower trapezius). Closed kinetic chain exercises and rhythmic stabilization drills.
• Phase IV (Months 3-6: Advanced Functional Return): High-velocity plyometrics, sport-specific overhead throwing progressions, and proprioceptive neuromuscular facilitation (PNF). Clearance for unrestricted return to sport requires symmetric rotator cuff strength (≥90% of contralateral side), full pain-free motion, and negative apprehension.

Operative Management

The goals of surgery are anatomical restoration of the capsulolabral bumper, elimination of capsular redundancy, correction of glenoid and humeral bone loss, and conversion of off-track biomechanics into an on-track joint:

• Arthroscopic Bankart Repair: Indicated for patients with isolated capsulolabral tears, minimal glenoid bone loss (<13.5%), and on-track Hill-Sachs lesions. The anteroinferior labrum must be completely mobilized from the 1 o’clock position down to the 6 o’clock position on the glenoid neck until subscapularis muscle fibers are visualized. The anterior glenoid neck is lightly decorticated to expose bleeding cancellous bone. A minimum of three (often four) suture anchors (2.4 mm to 3.0 mm, knotless or knotted) are placed on the articular face margin at the 3:00, 4:30, and 5:30 positions. Suture passages capture the inferior capsule and labrum, performing a superior and lateral capsular shift to tension the IGHLC.
• Arthroscopic Bankart with Remplissage: Insetting the infraspinatus tendon and posterior joint capsule into an engaging Hill-Sachs defect using 1 to 2 suture anchors placed within the humeral crater. Indicated for off-track Hill-Sachs lesions with glenoid bone loss <13.5% to 15%. Remplissage fills the defect and makes it extra-articular, converting an off-track lesion to an on-track lesion with minimal loss of external rotation (typically 2° to 6°).
• Open Latarjet Coracoid Transfer: Gold standard for recurrent anterior instability with significant bone loss. Through a deltopectoral approach, the coracoid process is osteotomized at its knee (preserving the conjoint tendon attachment of the coracobrachialis and short head of biceps) and mobilized. Through a horizontal split in the subscapularis, the coracoid graft is placed flush with the anteroinferior glenoid articular surface (0-1 mm medial, never lateral) and secured with two 3.5 mm or 4.0 mm cannulated bicortical screws. The procedure provides a dynamic triple-blocking effect: (1) Osseous effect restoring the anteroinferior glenoid articular diameter and surface area; (2) Sling effect wherein the conjoint tendon and lower third of the subscapularis dynamically compress the humeral head during abduction and external rotation; and (3) Capsular repair by suturing the coracoacromial ligament stump to the anterior capsule.
• Free Bone Grafting (Eden-Hybinette / Distal Tibia Allograft): Indicated for severe glenoid bone loss (>25% to 30%), revision cases with a fractured or lysed previous coracoid graft, or when the coracoid is anatomically deficient. Involves autologous tricortical iliac crest bone graft (Eden-Hybinette) or fresh-frozen distal tibia osteochondral allograft fixed to the anterior glenoid neck.

Indications & Contraindications

Surgical decision-making adheres to validated numerical thresholds and clinical parameters:

• Acute Bony Bankart Fracture: Displaced anteroinferior glenoid rim fracture involving >20% to 25% of the articular surface or with articular step-off >2 mm requires acute anatomical open or arthroscopic reduction and screw/anchor fixation.
• Recurrent Instability with Minimal Bone Loss: Young, active collision athletes with glenoid bone loss <13.5% and an on-track Hill-Sachs lesion are indicated for arthroscopic Bankart repair with capsular shift.
• Off-Track Hill-Sachs with Preserved Glenoid: Engaging off-track Hill-Sachs lesions with glenoid bone loss <13.5% to 15% are indicated for arthroscopic Bankart repair combined with remplissage.
• Subcritical or Critical Glenoid Bone Loss: Glenoid bone loss >13.5% to 15% (subcritical) in collision/contact athletes, or >20% to 25% (critical) in any patient, or an ISIS >6 represents an absolute indication for open Latarjet coracoid transfer.
• Acute Irreducible Dislocation: Irreducibility due to soft-tissue interposition (subscapularis tendon, long head of biceps, displaced labral flap) or capsular buttonholing requires urgent open reduction.
• Concomitant Rotator Cuff Tears: Full-thickness tears of the subscapularis and/or supraspinatus tendons in patients >40 years require acute surgical repair within 2 to 3 weeks of injury.
• Absolute Contraindications: Active glenohumeral joint sepsis, severe medical comorbidities precluding surgical anesthesia, and voluntary habitual non-traumatic dislocators with unmanaged psychiatric illness.
• Relative Contraindications: Isolated soft-tissue arthroscopic Bankart repair is contraindicated in patients with >15% glenoid bone loss, engaging off-track Hill-Sachs lesions, or ISIS >6 due to unacceptable recurrence rates approaching 70%.

9. Outcome

Validated Patient-Reported Outcome Measures (PROMs)

Clinical success is evaluated using disease-specific shoulder instruments:

• Western Ontario Shoulder Instability Index (WOSI): Gold standard, 21-item disease-specific health-related quality-of-life tool measuring physical symptoms, sports/recreation, lifestyle, and emotions (score 0 to 2100, converted to percentage). MCID is approximately 10.4%.
• Rowe Score for Instability: 100-point scale evaluating stability (50 points), motion (20 points), and function (30 points). Scores >90 indicate excellent outcome; <70 indicates failure.
• American Shoulder and Elbow Surgeons (ASES) Score: 100-point composite evaluating pain (50 points) and activities of daily living (50 points). MCID is approximately 6.4 to 9.7 points.
• Single Assessment Numeric Evaluation (SANE): Single-question percentage score rating shoulder function compared to normal (0% to 100%). Correlates strongly with ASES and WOSI.

Comparative Recurrence & Procedural Survivorship

Long-term recurrence rates vary significantly according to patient selection and procedural choice:

• Arthroscopic Bankart Repair: In properly selected patients without significant bone loss, modern suture anchor Bankart repair yields recurrence rates of 4% to 11% in randomized clinical trials. However, when applied indiscriminately to contact athletes or patients with unrecognized subcritical bone loss (>13.5%), recurrence rates escalate to 30% to 50%.
• Arthroscopic Bankart with Remplissage: In patients with off-track Hill-Sachs lesions and minimal glenoid bone loss, adding remplissage decreases recurrence from 30% to 40% down to 2% to 6%, matching the stability of open bone-block procedures while maintaining an arthroscopic approach.
• Open Latarjet Coracoid Transfer: Gold standard for bone loss and revision instability. Demonstrates durable long-term stability with redislocation rates of 1% to 4% at 10 to 20 years follow-up. Return to competitive sports exceeds 85% to 95%, with over 80% returning to their pre-injury level of performance.

Return-to-Play Metrics & Functional Timelines

Functional milestones dictate progressive return to athletic competition:

• Nonoperative Treatment: 6 to 12 weeks, depending on symptom resolution, complete rotator cuff strength restoration, and negative apprehension. Young contact athletes returning nonoperatively face an 80% to 90% reinjury rate.
• Arthroscopic Bankart Repair: 5 to 6 months for non-contact overhead sports; 6 to 9 months for collision and contact athletes (rugby, football, hockey), requiring full symmetric strength and psychological readiness.
• Open Latarjet Coracoid Transfer: 4 to 6 months for collision athletes, contingent upon CT confirmation of complete bony union between the coracoid graft and glenoid neck.

10. Complications

Complications following glenohumeral dislocation and operative stabilization are categorized by chronological onset:

11. Pearls and Pitfalls

• The 6 O’Clock Labral Mobilization Pearl: In arthroscopic Bankart repair, release the anterior-inferior labral sleeve completely from the 1 o’clock position down to the 6 o’clock position on the glenoid neck. Mobilization is complete only when the muscular fibers of the subscapularis (“subscapularis roll”) are cleanly visualized beneath the capsule. Failure to mobilize down to 6 o’clock prevents anatomical superior shift and results in an incompetent, tethered repair.
• The Pre-Reduction Radiograph Mandate: Never attempt closed reduction without obtaining an orthogonal radiographic series including a true AP and axillary lateral (or Velpeau) view, except on the athletic field when witnessed by medical staff immediately post-injury. Failing to identify a concomitant displaced humeral neck fracture prior to reduction risks displacing the head into the axilla and creating avascular necrosis.
• Latarjet Graft Flush Placement Pearl: The coracoid graft must be positioned strictly flush or 0 to 1 mm medial to the glenoid articular surface. Placing the graft even 1 mm lateral creates a rigid osseous step-off that rapidly destroys humeral head cartilage within 12 to 24 months. Placing it more than 5 mm medial eliminates the osseous augmentation effect, causing persistent instability.
• Bicortical Screw Trajectory in Latarjet: Drill holes and cannulated screws for the Latarjet procedure must be directed parallel to the glenoid articular face and angled approximately 10° to 15° medially relative to the scapular neck to achieve secure bicortical purchase while avoiding intra-articular penetration.
• Missed Posterior Dislocation Pitfall: Up to 50% of posterior dislocations are missed on initial emergency department evaluation due to reliance on non-orthogonal AP radiographs. An axillary lateral or Velpeau view is mandatory for every painful shoulder. Any patient with a shoulder locked in internal rotation who cannot externally rotate to neutral has a posterior dislocation until proven otherwise.
• The Older Dislocator Rotator Cuff Blindspot: In patients older than 40 years presenting with anterior dislocation, an inability to actively elevate the arm after reduction is frequently misattributed to axillary nerve neuropraxia. In reality, full-thickness rotator cuff tears occur in 30% to 70% of these patients. Prompt MRI within 1 to 2 weeks is mandatory, as acute repair of traumatic cuff tears yields dramatically superior clinical results compared to delayed reconstruction.
• The Subcritical Bone Loss Trap: Do not perform isolated soft-tissue Bankart repair in high-demand collision athletes with glenoid bone loss between 13.5% and 15%. Although historically classified as “subcritical,” this level of osseous deficiency leads to unacceptably high failure rates unless addressed with a Latarjet procedure or remplissage.

12. Controversy

Immediate Primary Stabilization vs Nonoperative Care in Young First-Time Dislocators

The management of first-time anterior glenohumeral dislocation in adolescents and young adults (aged <25 years) remains intensely debated. Proponents of immediate arthroscopic Bankart repair emphasize Level I randomized trials (Robinson et al., Kirkley et al.) demonstrating that primary stabilization reduces the risk of recurrent instability from ∼50-80% down to ∼10-15%, prevents progressive glenoid and humeral bone loss, and yields superior disease-specific quality of life (WOSI scores). Conversely, advocates of nonoperative management argue that immediate surgery over-treats the 15% to 20% of young patients who may never experience a second dislocation, exposing them to unnecessary surgical risks and healthcare costs. Current consensus increasingly favors primary arthroscopic repair in young, high-demand competitive contact and collision athletes, while a trial of structured nonoperative rehabilitation is reserved for recreational athletes willing to accept the risk of redislocation.

Immobilization in External Rotation vs Internal Rotation

In 2007, Itoi and colleagues published landmark clinical and MRI data suggesting that immobilizing the arm in 10° to 30° of external rotation tensions the subscapularis tendon, dynamically reducing and coapting the torn anteroinferior Bankart lesion to the glenoid neck, significantly lowering recurrence compared to conventional internal rotation slings. However, subsequent large-scale prospective multicenter randomized trials in North America and Europe failed to reproduce these superior outcomes. Major trials highlighted poor patient compliance with cumbersome external rotation braces and found no statistically significant difference in redislocation rates at 2- and 5-year follow-up. Consequently, current clinical practice guidelines recommend short-term (1 to 2 weeks) immobilization in a standard sling worn strictly for comfort, followed by early functional motion.

Critical vs Subcritical Glenoid Bone Loss Thresholds

Historically, the threshold for abandoning soft-tissue Bankart repair in favor of bony reconstruction was established at 20% to 25% glenoid bone loss (the classic “critical” threshold described by Burkhart and De Beer). However, contemporary biomechanical and clinical registry studies have demonstrated that glenoid bone loss between 13.5% and 15% (termed “subcritical” bone loss) is associated with unacceptably high rates of recurrent instability (exceeding 30%) and significantly worse postoperative WOSI scores following isolated arthroscopic Bankart repair, particularly in military personnel and competitive collision athletes. Modern consensus has shifted towards recommending bony augmentation (open Latarjet coracoid transfer) for high-demand collision athletes with subcritical bone loss >13.5% to 15%, reserving isolated Bankart repair for patients with negligible bone loss (<13.5%) and on-track Hill-Sachs lesions.

Arthroscopic vs Open Latarjet Coracoid Transfer

The adoption of all-arthroscopic Latarjet coracoid transfer (pioneered by Lafosse) has introduced a major clinical and technical divide. Proponents of the arthroscopic technique highlight superior intra-articular visualization, precise flush placement of the graft along the glenoid face, simultaneous treatment of associated intra-articular pathology (biceps, posterior labrum), lower wound complication rates, and improved cosmetic outcomes. Opponents cite a formidable learning curve (requiring 30 to 50 cases to achieve technical proficiency), significantly prolonged operative times, high conversion rates, and increased risks of catastrophic neurovascular complications during initial surgeon adoption. At present, open Latarjet remains the global gold standard of care due to its reproducibility, safety profile, and predictable long-term bony union, while arthroscopic Latarjet is concentrated primarily in high-volume specialized shoulder centers.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Kirkley A, Griffin S, Richards C et al. Prospective randomized clinical trial comparing the effectiveness of immediate arthroscopic stabilization versus immobilization and rehabilitation in first traumatic anterior dislocations of the shoulder. Arthroscopy. 1999. doi:10.1053/ar.1999.v15.015050 [Level I (Therapeutic): Randomized Controlled Trial]
• Bottoni CR, Smith EL, Berkowitz MJ et al. Arthroscopic versus open shoulder stabilization for recurrent anterior instability: a prospective randomized clinical trial. Am J Sports Med. 2006. doi:10.1177/0363546506288239 [Level I (Therapeutic): Randomized Controlled Trial]
• Robinson CM, Jenkins PJ, White TO et al. Primary arthroscopic stabilization for a first-time anterior dislocation of the shoulder. A randomized, double-blind trial. J Bone Joint Surg Am. 2008. doi:10.2106/JBJS.G.00679 [Level I (Therapeutic): Randomized Controlled Trial]
• Balg F, Boileau P. The instability severity index score. A simple pre-operative score to select patients for arthroscopic or open shoulder stabilisation. J Bone Joint Surg Br. 2007. doi:10.1302/0301-620X.89B11.18962 [Level IV (Prognostic): Prospective Cohort Study]
• Itoi E, Hatakeyama Y, Sato T et al. Immobilization in external rotation after shoulder dislocation reduces the risk of recurrence. A randomized controlled trial. J Bone Joint Surg Am. 2007. doi:10.2106/JBJS.F.00654 [Level I (Therapeutic): Randomized Controlled Trial]

15. Master Class Pro-Tip

When addressing recurrent anterior glenohumeral instability in an athlete, the single greatest technical error in arthroscopic Bankart repair is incomplete capsulolabral mobilization. The anteroinferior labrum must be mobilized from the 1 o’clock position all the way down to the 6 o’clock position on the glenoid neck until the muscular fibers of the subscapularis (‘subscapularis roll’) are cleanly exposed beneath the inferior capsule. Mobilizing only down to 4:30 creates a tethered, medialized repair that leaves the inferior pouch patulous, virtually guaranteeing recurrence. Furthermore, never commit to an isolated soft-tissue repair without calculating the glenoid track on 3D CT. In a contact athlete with subcritical bone loss between 13.5% and 15% or an engaging off-track Hill-Sachs lesion, proceed directly to an open Latarjet coracoid transfer or add a remplissage; soft-tissue anchors alone cannot overcome osseous biomechanical deficits.

Master Class Surgical Pearl: Anterior Capsulolabral Mobilization and Bipolar Bone Loss