Shoulder Labral Injury

Populations and Risk Factors

• Overhead athletes: baseball pitchers, swimmers, volleyball players, tennis players — repetitive overhead motion creates torsional stress on the superior labrum during the late cocking and deceleration phases of throwing
• History of shoulder dislocation: anterior dislocation tears the anteroinferior labrum (Bankart lesion) in approximately 90% of traumatic first-time dislocations in young adults; each subsequent dislocation extends the labral damage
• Contact sport athletes: rugby, football, hockey — direct blows and falls on outstretched hands (FOOSH) produce macrotraumatic labral avulsion
• Age-related degeneration: labral tissue becomes more brittle and less vascular with age; degenerative SLAP lesions (Type I) are common after age 40 and may be incidental findings on MRI
• Glenohumeral instability or hypermobility: excessive humeral head translation stresses the labrum as the primary passive restraint
• Males affected more frequently than females (approximately 3:1) due to higher participation in overhead and contact sports

Causes and Pathophysiology

Labral Anatomy and Function

• The glenoid labrum is a ring of fibrocartilage attached to the rim of the glenoid fossa. It deepens the socket by 30-50%, converting the flat glenoid into a more concave surface that cradles the humeral head. Without the labrum, the glenohumeral joint has minimal bony congruence (the glenoid covers only about one-third of the humeral head surface).
• The labrum creates a suction-cup seal with the humeral head, generating negative intra-articular pressure that resists distraction and translation. This mechanism is the primary passive stabilizer of the GH joint at mid-range, where the ligaments are lax.
• The superior labrum serves as the anchor point for the long head of biceps tendon (LHBT). This biceps-labral complex is critical because biceps contraction during overhead activity generates a torsional pull on the superior labrum — the mechanism underlying SLAP lesions.
• The anteroinferior labrum merges with the inferior glenohumeral ligament (IGHL), forming a "bumper" that resists anterior humeral head translation during abduction and external rotation. Damage to this region (Bankart lesion) eliminates the primary restraint against anterior dislocation.

SLAP Lesions (Superior Labrum Anterior to Posterior)

• Type I: Fraying and degeneration of the superior labral edge; the labrum and biceps anchor remain firmly attached to the glenoid. Common age-related finding. Clinically: mild mechanical symptoms; often incidental on MRI.
• Type II: The superior labrum and biceps anchor are detached from the glenoid rim, creating a flap that can catch between the humeral head and glenoid during overhead motion. This is the most common and clinically significant SLAP type (approximately 55% of SLAP lesions). The "peel-back" mechanism in overhead athletes is the classic cause: during the late cocking phase, the arm is maximally abducted and externally rotated, and the biceps tendon twists posteriorly, peeling the labrum off the glenoid.
• Type III: A bucket-handle tear of the superior labrum — a displaced labral fragment drops into the joint, causing mechanical locking. The biceps anchor remains intact. Clinically: intermittent locking and catching; may mimic loose body symptoms.
• Type IV: A bucket-handle tear that extends into the long head of biceps tendon itself. The biceps anchor is compromised. Clinically: biceps pain and dysfunction are more prominent than in Types I-III; the displaced fragment causes mechanical symptoms.

Bankart Lesion

• Anteroinferior labral avulsion, typically caused by traumatic anterior glenohumeral dislocation. As the humeral head translates anteriorly and inferiorly over the glenoid rim, it shears the anteroinferior labrum off the glenoid.
• Bony Bankart: The labral avulsion includes a fracture fragment from the anterior glenoid rim. This further reduces the bony surface area available to contain the humeral head, significantly increasing recurrence risk. A bony Bankart involving more than 20-25% of the glenoid diameter often requires surgical reconstruction.
• The Bankart lesion eliminates the anteroinferior "bumper" and disrupts the IGHL attachment, removing the primary passive restraint against anterior translation. This is why anterior dislocation with a Bankart lesion creates persistent anterior instability.

Hill-Sachs Lesion

• A compression fracture on the posterolateral humeral head, created when the hard anterior glenoid rim impacts the softer humeral head during anterior dislocation. The defect is found in approximately 80% of first-time anterior dislocations and nearly 100% of recurrent dislocations.
• A large Hill-Sachs lesion can "engage" the anterior glenoid rim during external rotation and abduction, producing a mechanical catch and increasing the risk of recurrent dislocation. The combination of a Hill-Sachs lesion (humeral side deficiency) and a Bankart lesion (glenoid side deficiency) represents a bipolar lesion that substantially compromises joint stability.

Glenohumeral Internal Rotation Deficit (GIRD)

• Overhead athletes with SLAP lesions frequently develop GIRD — loss of glenohumeral internal rotation exceeding 20 degrees compared to the non-throwing shoulder, with preserved or increased external rotation (total rotation arc may be preserved).
• GIRD results from posterior capsular contracture (adaptive stiffening from repetitive overhead use) combined with osseous retroversion changes. The tight posterior capsule shifts the contact point of the humeral head anterosuperiorly during forward flexion, increasing stress on the anterosuperior labrum and biceps anchor — contributing to SLAP development.

Signs and Symptoms

By Lesion Type

General Presentation

• Clicking, catching, or locking during shoulder movement — mechanical symptoms from the torn labral fragment interacting with the humeral head or glenoid during motion
• Deep, vague shoulder pain worsened by overhead reaching, throwing, or pushing activities; patients often cannot localize the pain precisely (the labrum is deep and poorly innervated)
• "Dead arm" syndrome: sudden transient shooting pain with loss of arm strength during overhead activity, characteristic of Type II SLAP lesions — the biceps anchor momentarily fails under load
• Sensation of the shoulder "slipping out" or giving way — characteristic of Bankart lesions with anterior instability; patients may feel the humeral head translate and then reduce
• GIRD: significant internal rotation deficit in the throwing shoulder compared to the non-dominant side (overhead athletes)
• Night pain if the labral tear creates persistent inflammation; may worsen with specific arm positions that load the torn region

Assessment Profile

Subjective Presentation

• Chief complaint: "My shoulder clicks and catches when I move it"; "it feels like my shoulder wants to pop out when I throw"; "I get a dead arm feeling when I reach overhead"; deep, vague pain that is difficult to localize
• Pain quality: Deep, aching pain within the shoulder joint; sharp catching or locking sensation with specific movements; anterior pain with Bankart lesions; posterosuperior or deep anterior pain with SLAP lesions; "dead arm" episodes — sudden sharp pain with transient loss of strength
• Onset: Traumatic: acute onset after a fall on outstretched hand (FOOSH), direct blow to the shoulder, or shoulder dislocation event (Bankart); insidious: gradual onset in overhead athletes with increasing throwing volume or intensity (SLAP Type II — cumulative peel-back microtrauma); degenerative: incidental finding without clear onset (Type I)
• Aggravating factors: Overhead reaching and throwing (especially the late cocking and deceleration phases); reaching behind the back; pushing or pulling movements; sleeping on the affected side; activities requiring sustained arm elevation; the apprehension position (abduction + ER) for Bankart lesions
• Easing factors: Avoiding overhead activities; keeping the arm close to the body; avoiding the provocative position; activity modification reducing throwing volume
• Red flags: Sudden loss of pulse, coolness, pallor, or mottled skin in the hand after a shoulder injury or dislocation event — emergency referral for possible axillary artery damage; do not treat. Sudden onset of complete weakness with inability to abduct (regimental badge numbness) suggests axillary nerve injury.

Observation

• Local inspection: Typically unremarkable in isolated labral tears; supraspinatus or infraspinatus fossa wasting may be present if a suprascapular nerve cyst (ganglion arising from the labral tear) compresses the suprascapular nerve; anterior fullness or asymmetry may be visible with recurrent subluxation (Bankart)
• Posture: May show protective guarding with the arm held close to the body in internal rotation (especially post-dislocation/Bankart); overhead athletes may demonstrate forward shoulder posture with scapular protraction (adaptive changes from repetitive overhead use)
• Gait: Not directly affected; arm swing may be guarded on the affected side

Palpation

• Tone: Pectoralis major and subscapularis hypertonicity from protective guarding against anterior translation in Bankart lesions. Infraspinatus and posterior deltoid guarding. Upper trapezius and levator scapulae compensatory hypertonicity. Biceps long head may be tender and hypertonic, especially in SLAP Type II and IV.
• Tenderness: Anterior GH joint line tenderness (Bankart — palpate with the arm in slight extension and ER to bring the anterior capsule forward); posterior GH joint line tenderness (posterior labral involvement); bicipital groove tenderness (SLAP lesions involving the biceps anchor); tenderness may be difficult to elicit because the labrum is deep — reliance on provocation tests is greater than for superficial structures
• Temperature: Usually normal; mild warmth may indicate active joint inflammation or acute post-dislocation effusion
• Tissue quality: Long head of biceps tendon may feel thickened or fibrotic in chronic SLAP lesions; posterior capsule may feel taut and inelastic (GIRD in overhead athletes); pectoralis major and subscapularis may feel shortened and fibrotic in chronic anterior instability presentations

Motion Assessment

• AROM: Overhead flexion and abduction may produce clicking, catching, or apprehension rather than pure pain. Internal rotation may be significantly reduced (GIRD — compare bilateral; > 20 degree deficit is clinically significant). External rotation may be increased in the throwing shoulder (posterior capsular laxity or adaptive osseous changes). Combined abduction + ER (apprehension position) may produce guarding or a sense of instability rather than simple pain (Bankart).
• PROM / end-feel: PROM may reveal mechanical catching or clunking during rotation — the examiner may feel the labral fragment interacting with the joint surfaces. End-feel in the apprehension position (90 degrees abduction + ER) may produce guarding/empty end-feel rather than a normal tissue stretch (the patient stops the movement before tissue resistance — fear of dislocation). Passive IR deficit (GIRD) with a firm end-feel indicates posterior capsular contracture. PROM is generally greater than AROM; global restriction in a capsular pattern is not present (distinguishes from adhesive capsulitis).
• Resisted testing: Resisted shoulder flexion with elbow extended and forearm supinated (Speed's test position) may reproduce anterior/superior shoulder pain (SLAP lesion loading the biceps anchor). Resisted ER and IR are usually strong and pain-free unless there is concurrent rotator cuff involvement. Isometric biceps testing (resisted elbow flexion and supination) may reproduce deep shoulder pain in Type II and IV SLAP lesions.

Special Test Cluster

SLAP vs. Bankart cluster: For suspected SLAP lesion, lead with O'Brien's + Speed's. For suspected Bankart/instability, lead with Apprehension + Relocation. The Crank test is useful for either type. MRI arthrogram (with gadolinium contrast) is the gold standard for definitive labral tear identification — clinical tests guide the referral decision.

Differential Diagnoses