Overview & Definition
SLAP tears (Superior Labrum Anterior to Posterior tears) are lesions of the superior glenoid labrum extending anterior and/or posterior to the biceps anchor. They were first classified systematically by Stephen Snyder in 1990 following his description of the arthroscopic anatomy of the superior labrum and biceps anchor. SLAP tears are a significant cause of shoulder pain and dysfunction in overhead athletes (throwing athletes, swimmers, racquet sport players) but also occur from acute traction injuries, falls onto an outstretched hand, and degenerative changes in older patients. The clinical diagnosis is challenging — no single clinical test has sufficient sensitivity and specificity to reliably diagnose a SLAP tear; MR arthrography is the investigation of choice.
- Biceps anchor anatomy: the long head of the biceps (LHB) originates from the superior glenoid labrum and the supraglenoid tubercle; approximately 50% of the biceps origin is from the posterior-superior labrum and 50% from the supraglenoid tubercle; the superior labrum is the most mobile portion of the labrum (less firmly attached than the anterior or posterior labrum) — this allows the normal physiological `peel-back` mechanism in throwing athletes; the superior labrum is attached to the superior glenoid via the labral-cartilage complex; the normal anatomy includes the `sublabral foramen` (an inferior-anterior subtype of labral non-attachment — normal variant) and the `Buford complex` (cord-like anterior band of MGHL with absence of the anterior-superior labrum — normal variant in 1.5% of shoulders; must not be mistaken for a SLAP tear)
- Mechanism: (1) peel-back mechanism — in overhead throwing athletes, the arm reaches the late-cocking position (maximal external rotation and abduction); the LHB becomes taut in this position and rotates posteriorly, `peeling` the biceps anchor and superior labrum away from the supraglenoid tubercle posteriorly — this is the mechanism for Type II SLAP tears in throwers; (2) FOOSH (fall onto outstretched hand) with superior labral compression — the humeral head is driven superiorly, compressing the superior labrum; (3) traction injury — sudden traction on the arm (catching a falling object); (4) deceleration mechanism in throwing — the posterior biceps force during deceleration avulses the posterior superior labrum
Snyder Classification (1990) — Types I–IV + Extensions
| Type | Description | Biceps Anchor | Frequency | Treatment |
|---|---|---|---|---|
| Type I | Fraying and degeneration of the superior labrum WITHOUT detachment; the labrum appears frayed or degenerative but remains attached to the glenoid; this is the most `normal` finding and may represent age-related degeneration | INTACT and STABLE — the biceps anchor is not disturbed | ~21% | Debridement of frayed tissue; no repair required; address any concurrent pathology; outcomes are generally good |
| Type II — Most common and most important | DETACHMENT of the superior labrum AND biceps anchor from the supraglenoid tubercle; the superior labrum-biceps complex peels away from the superior glenoid; a gap is visible between the labrum and the glenoid under arthroscopy when the biceps is tensioned; the glenoid articular cartilage is exposed; three subtypes (Morgan): IIA (anterior detachment only), IIB (posterior detachment only — most common in throwing athletes), IIC (combined anterior and posterior — the most extensive) | UNSTABLE — the biceps anchor is avulsed from the supraglenoid tubercle; the biceps `drive-through` sign is positive (a probe can be passed behind the biceps root into the detached space) | ~41% — the most common SLAP type; the most surgically significant; the `classic` SLAP tear requiring repair | SLAP repair (suture anchor fixation of the superior labrum-biceps complex to the supraglenoid tubercle) in young overhead athletes; biceps tenodesis or tenotomy in older patients (>40 years) or those not returning to overhead sport (see below) |
| Type III | A `bucket-handle` tear of the superior labrum; the central portion of the superior labrum displaces into the joint (like a bucket handle flipping into the joint) while the biceps anchor REMAINS INTACT; the biceps root is stable; the displaced labral fragment may cause mechanical symptoms (locking, clicking) | INTACT and STABLE — the biceps anchor is NOT involved; the tear is in the labral body only | ~33% | Resection (debridement) of the displaced bucket-handle fragment; the biceps anchor is stable so no repair of the anchor is required; outcomes are generally good |
| Type IV | A bucket-handle tear of the superior labrum that EXTENDS INTO the biceps tendon itself; the bucket-handle labral tear propagates into and splits the biceps tendon; the biceps tendon has a vertical split with the inner portion displaced into the joint with the labral bucket-handle fragment | INVOLVED — the biceps tendon itself is partially torn; the anchor may be stable or unstable depending on the extent of the tear | ~5% | Depends on age and extent: young athletes with <50% biceps tendon involvement → repair of the labrum and biceps tendon; >50% biceps involvement or older patients → biceps tenodesis + debridement of unstable labral tissue |
- Types V–X (Maffet extensions): subsequent authors added additional SLAP subtypes (V — SLAP extending into the Bankart lesion; VI — unstable radial flap tear with biceps detachment; VII — SLAP extending into the MGHL; VIII — SLAP extending posteriorly; IX — circumferential labral tear; X — SLAP combined with posterior inferior labral tear); these extended types are less commonly used in clinical practice; the original four Snyder types remain the most examined and most practically relevant
Clinical Diagnosis
- Symptoms: deep shoulder pain; pain at the late-cocking phase of throwing (the arm is at maximum external rotation and abduction); clicking or popping; weakness during throwing; loss of velocity in throwing athletes; inability to maintain high-level throwing; pain with overhead activities; may also present with biceps pain (anterior shoulder)
- Clinical tests (all have limited diagnostic accuracy individually): (1) Speed test — resisted elbow flexion with the arm elevated at 90°, elbow extended, forearm supinated; positive if bicipital groove pain reproduced (sensitivity 32%, specificity 61% for SLAP); (2) O`Brien active compression test — arm at 90° forward flexion, 10–15° adduction, elbow extended; first with forearm pronated (thumb down) then with forearm supinated; positive = pain with pronation that decreases or disappears with supination; sensitivity ~63%, specificity ~73% for SLAP; (3) Crank test — arm at 160° abduction; examiner applies axial load and rotates the humerus; positive = pain or click; sensitivity ~91% for SLAP (though this figure is controversial); (4) Kim test — arm at 90° abduction; examiner applies posterosuperior axial force while adducting the arm 45°; positive = sudden posterior shoulder pain; good sensitivity for posterior-superior labral tears; NO single test is diagnostic — a combination of tests improves accuracy; MRA is essential for pre-operative confirmation
SLAP Repair vs Biceps Tenodesis — Decision Making
| Procedure | Indication | Advantage | Disadvantage |
|---|---|---|---|
| SLAP repair | Young overhead athletes (<35 years); competitive throwers; swimmers; racquet sport athletes; acute traumatic SLAP (Type II) in young patients | Preserves the biceps anchor and the normal shoulder biomechanics; maintains the suction seal of the superior labrum; allows full return to overhead sport in young athletes; return-to-sport rates in competitive throwers ~63–83% | High stiffness rate post-operatively; restricted external rotation post-op → loss of late-cocking position in throwers; lower return-to-throwing rates than expected; technically demanding; longer rehabilitation (6–9 months to return to competitive throwing) |
| Biceps tenodesis | Patients >35–40 years; non-overhead athletes or sedentary individuals; concurrent significant biceps tendon pathology (partial tear, tenosynovitis); failed prior SLAP repair; combined SLAP + biceps tendon disease; workers who need early return to activity | Removes the pain source (the pathological biceps-superior labrum complex) reliably; excellent pain relief; simpler surgery; fewer complications; faster return to activity; outcomes are equal or superior to SLAP repair in patients >35 years (Denard 2012, Boileau 2012) | Does not allow return to overhead competitive throwing; alters the normal shoulder biomechanics; risk of cosmetic `Popeye deformity` if tenotomy rather than tenodesis is performed |
| Biceps tenotomy | Elderly, low-demand patients; severe systemic disease; as an adjunct in massive cuff repair | Simplest procedure; excellent pain relief; no fixation required | Cosmetic `Popeye deformity` (~70% of cases); 10–15% loss of forearm supination strength; not appropriate for younger or cosmesis-conscious patients |
Exam Pearls
- Snyder classification: Type I (fraying, no detachment, debridement); Type II (detachment of labrum + biceps anchor — MOST COMMON AND MOST IMPORTANT, suture anchor repair or tenodesis); Type III (bucket-handle, biceps anchor intact, debridement); Type IV (bucket-handle extending into biceps tendon, repair vs tenodesis depending on age/extent)
- Peel-back mechanism: late-cocking position (max ER + abduction) → LHB rotates posteriorly → peels the biceps anchor and superior labrum off the supraglenoid tubercle → Type IIB posterior SLAP; the classic mechanism in throwing athletes
- O`Brien active compression test: arm 90° flexion + 10–15° adduction; pain with pronation (thumb down) that decreases with supination = positive SLAP; sensitivity ~63%, specificity ~73%; the most commonly used SLAP test
- MR arthrography: investigation of choice; gadolinium enters the detached labral-biceps complex; signal between the superior labrum and the glenoid on coronal sequence = Type II detachment; normal variant must be excluded (sublabral foramen at 1-3 o`clock anterosuperior; Buford complex = cord MGHL + absent anterosuperior labrum)
- SLAP repair vs tenodesis: repair for young overhead athletes; tenodesis for >35–40 years / non-throwers / failed prior repair; evidence (Boileau 2012, Denard 2012) shows tenodesis has superior outcomes in older patients; return-to-competitive-throwing after SLAP repair ~63–83% (much lower than expected)
- Buford complex: cord-like MGHL + absent anterosuperior labrum; normal variant in 1.5% of shoulders; mimics a SLAP tear on MRI — do NOT repair; the cord-like MGHL is actually thicker and more prominent than normal; repair would cause stiffness