SLAP is the abbreviated term for Superior Labral Anterior to Posterior tear and refers to a damage to the glenoid labrum occurring from the anterior to the posterior side.
The head of the humerus, fitting in the glenoid cavity, is stabilised by the glenoid labrum and the tendon of the long head of the biceps muscle, which inserts at the top of the labrum at a 12 o’clock position (see image). The glenoid labrum is a cuff consisting of a fibro-cartilaginous rim attached to the edge of the glenoid cavity. The labrum is susceptible to injury with overuse and trauma to the shoulder. Particularly the anterior-superior labrum is poorly vascularised and thus more vulnerable to damage. In the ageing process the labrum becomes brittle and can fray or tear more easily.
The classification of SLAP injuries depends on the type and severity of the damage to the labrum. A SLAP tear is subdivided into four types:
Type 1 Fraying of the superior labrum while the biceps anchor remains intact.
Treatment: Debridement of the frayed edge.
Type 2 Superior labrum is detached with detachment of the biceps anchor.
Treatment: Debridement of superior glenoid rim and surgical reattachment of biceps and labrum.
Type 3 Bucket handle type tear of superior labrum with the biceps anchor intact.
Treatment: Resection of tear.
Type 4 Bucket handle tear of the superior labrum with extension into the biceps tendon. Part of the biceps anchor is still intact.
Treatment: Resection of tear and if over 50% of the tendon is also involved, tenodesis is recommended (surgical reattachment of a tendon the bone).
A labral tear or SLAP is often caused by a fall on the outstretched arm or as a consequence of repetitive overhead activity such as when throwing the ball in baseball and cricket. It can also arise during heavy weight lifting.
The intrinsic poor vascularity of the glenoid labrum exposes this area to injury when strained. Weight lifting, overhead work and contact sports are the major risk factors for SLAP injuries.
The typical symptom of a SLAP lesion is a catching, popping and clicking sensation combined with pain while moving the shoulder, especially with overhead activity. The pain is located deep within or in the back of the shoulder joint. When SLAP tears are associated with biceps tendonitis, the patient may feel the pain over the anterior area of the shoulder. Shoulder weakness and reduced movement are additional symptoms of this pathology.
The detection of SLAP injury can be difficult. Although clinical examination may suggest a SLAP tear, the diagnosis may remain inconclusive. Specific tests such as provocative tests, biceps tendon function and apprehension test form part of the clinical examination. Ideally, an MRI scan with contrast is recommended to visualise the soft tissues around the shoulder joint and identify any abnormalities. X-rays are conducted to exclude other injuries associated with SLAP tear. Arthroscopic surgery is a more invasive method to confirm the presence of a labral tear in situ with ongoing symptomatology.
Conservative management of a SLAP tear includes resting in a sling followed by physical therapy with muscle exercise and shoulder capsule stretching. Anti-inflammatory treatment is advised to reduce local inflammation resulting from the injury.
Surgery for SLAP lesions is indicated in athletes and patients who intend to return to sport quickly and/or having symptoms persisting beyond three months of non-operative treatment. Arthroscopic repair of SLAP lesions is currently the standard treatment option to fix the torn labrum and reattach it to the glenoid. Several methods are available including debridement, partial resection of the labrum and suturing (sometimes using suture anchors).
Following arthroscopic repair of the injured labrum, the patient will use a sling for three weeks prior to commence physiotherapy. In athletes, throwing is only allowed after four months and full velocity movements recommended six to seven months later. These are general guidelines, which may vary depending on the type of injury, patient demographics and surgeon preferences.
Prevention of SLAP lesions is best achieved with adequate strengthening of the shoulder muscles and shoulder blades to increase the stability of the rotator cuff and, at least temporarily, avoid those movements involving overhead and contact activities that constitute a risk of recidivism. For professional athletes, it is critical to begin the training session with warm-up and stretching exercises and introduce a learning program for correct movement during throwing activity as well as methods of falling during sports. Particularly in the elderly it is critical to introduce any form of fall prevention.