SLAP Tear

SLAP (superior labrum anterior to posterior) tear is an injury of the superior glenoid labrum that involves the origin of the long head of the biceps tendon. It makes up about 6% of shoulder injuries seen at arthroscopy, and is common in overhead athletes (baseball pitchers, volleyball and tennis players, swimmers) and in manual labourers.

The Snyder classification describes four types. Type I is fraying and degeneration of the superior labrum with an intact biceps anchor (common in older adults and usually asymptomatic). Type II is detachment of the superior labrum and biceps anchor from the glenoid (the most common symptomatic type, subdivided into anterior, posterior or combined). Type III is a bucket handle tear of the labrum with an intact biceps anchor.

Type IV is a bucket handle tear extending into the biceps tendon. Types V to X (Maffet and others) add anterior inferior extension, posterior superior extension, Bankart lesions and rotator cuff tears.

Mechanisms are repetitive overhead throwing (the peel back mechanism and internal impingement), traction injury on the arm, a fall on an outstretched abducted arm, and direct compression. Complications are persistent pain and clicking, instability, rotator cuff tears, stiffness (posterior capsule tightness and glenohumeral internal rotation deficit), paralabral cysts with suprascapular neuropathy, and failure of repair (stiffness and persistent pain after type II repair in older adults).

Pathophysiology.

In throwing the arm in abduction and external rotation twists the biceps anchor in the late cocking phase (peel back), and the posterosuperior labrum is traumatised. Repetitive load, tight posterior capsule and scapular dyskinesis raise stress on the superior labrum. Paralabral cysts can form at the spinoglenoid notch and compress the suprascapular nerve.

Deep, poorly localised shoulder pain with overhead activity, a catching, clicking or popping sensation, loss of throwing velocity, reduced endurance and a "dead arm" feeling. Night pain is less common. Examine the shoulder range (glenohumeral internal rotation deficit), rotator cuff strength, scapular position, and the cervical spine.

• O'Brien active compression test (pain with the arm flexed 90 degrees, adducted 10 to 15 degrees and internally rotated, resisted elevation, relieved with the palm up).
• Speed test, Yergason test, biceps load test I and II, and the crank test.
• Dynamic labral shear test (Kibler), and the compression rotation test.
• Individual tests have limited accuracy; use a combination of tests with imaging.

• Radiographs: anteroposterior, scapular Y and axillary views, to exclude fractures, calcific tendinitis, Bennett lesion and arthritis.
• MR arthrography with intra-articular gadolinium is the best imaging (sensitivity and specificity of about 85 to 90%). A sublabral foramen or recess and a Buford complex are normal variants and can be mistaken for tears.
• Ultrasound for paralabral cyst and biceps tendon.
• Diagnostic arthroscopy gives the final diagnosis.
• Electromyography when there is a spinoglenoid cyst with weakness of the infraspinatus.

Differential diagnosis.

• Rotator cuff tear and subacromial impingement.
• Biceps tendinopathy or subluxation and Bankart lesion.
• Glenohumeral instability and AC joint arthritis.
• Cervical radiculopathy and suprascapular neuropathy.

Initial non-operative treatment for 3 to 6 months.

• Relative rest from overhead activity, avoidance of aggravating positions, ice and analgesia.
• Physiotherapy: posterior capsule stretching (the sleeper stretch and cross-body stretch), scapular stabiliser strengthening, rotator cuff and core strengthening, and a throwing mechanics assessment.
• Corticosteroid injection into the glenohumeral joint for pain: methylprednisolone acetate 40 mg with 3 to 5 mL of lidocaine 1%, given once under aseptic technique (repeat no sooner than 3 months, maximum 3 injections in 12 months). Check glucose in diabetes, and avoid with infection or in the first 2 weeks after surgery.

Surgery (failed 3 to 6 months of non-operative care, or acute type II in young athletes with mechanical symptoms).

• Type I: debridement.
• Type II: arthroscopic repair with suture anchors in patients under age 35 to 40. In patients over age 40, biceps tenodesis (subpectoral or arthroscopic) or tenotomy gives better results with a lower rate of stiffness.
• Type III: excision of the bucket handle fragment.
• Type IV: debridement and repair of the labrum if the biceps tear is under 30 to 50%, or biceps tenodesis if it is over 50%.
• Postoperative: sling for 4 weeks, passive movement from week 2, active movement from week 6, strengthening from week 12, and return to throwing at 4 to 6 months (full competition at 9 to 12 months).
• Paralabral cyst: arthroscopic labral repair with cyst decompression.

Operative antibiotic prophylaxis. Cefazolin 2 g intravenously (3 g when weight is 120 kg or over) within 60 minutes before incision as a single dose (repeat after 4 hours or blood loss over 1500 mL); with severe penicillin allergy, vancomycin 15 mg/kg intravenously starting 90 to 120 minutes before incision as a single dose, with levels and creatinine checked in prolonged cases.

Analgesia.

• Paracetamol 1 g orally every 6 hours as needed for up to 5 to 7 days (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).
• Ibuprofen 400 mg orally every 8 hours with food for up to 5 days (maximum 1200 mg daily); avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer, heart failure or anticoagulant use.
• Oral morphine 5 to 10 mg every 4 hours as needed for severe pain for up to 3 days (start 2.5 to 5 mg with age over 75 or eGFR under 30 mL/min/1.73 m2; avoid exceeding 60 mg in 24 hours without senior review); monitor sedation and respiration and prescribe a laxative.

Monitoring. Pain, range of motion (internal rotation deficit) and strength at 6 weeks, 3 months and 6 months. Throwing mechanics and load at return to sport. MR arthrography when symptoms persist or recur. Stiffness after repair at 6 weeks and 3 months.

Referral and escalation. Refer mechanical symptoms or failure of 3 months of rehabilitation to orthopaedics or sports surgery within 4 to 6 weeks. Urgent referral for infraspinatus wasting with a paralabral cyst, an acute traumatic tear with instability, or any neurovascular deficit.

Special groups.

• Overhead athletes: aim at the cause (posterior capsule tightness, scapular dyskinesis, throwing mechanics); return to throwing is slower after repair.
• Older adults: type II lesions are frequently degenerative; tenodesis is preferred to repair.
• Kidney impairment: avoid ibuprofen and reduce morphine doses.
• Diabetes: monitor glucose after steroid injection.