Arthroscopic Treatment of Superior Labral Anterior Posterior (SLAP) Tears

DEFINITION

Superior labral anterior posterior (SLAP) tears are characterized by injury to the superior glenoid labrum, with anterior to posterior detachment of the superior labrum.²⁵
- Tears can occur with or without involvement of the biceps tendon origin.⁴

ANATOMY

The superior glenoid labrum is composed of fibrocartilaginous tissue between the hyaline cartilage of the glenoid surface and the joint capsule fibrous tissue.²²
- This fibrocartilaginous tissue serves as the attachment between the labrum and glenoid.
- The vascular supply of the glenoid labrum does not come from the underlying glenoid but rather from penetrating branches of the suprascapular, circumflex scapular, and posterior humeral circumflex arteries in the surrounding capsule and periosteal tissue.
- There is histologic evidence that vascularity is decreased in the anterior, anterosuperior, and superior aspects of the glenoid labrum,⁷ although no distinct vascular transition zone has been described.¹⁵
- The inner portion of the glenoid labrum is avascular.²³

PATHOGENESIS

An intact labrum enhances concavity compression and increases the effective diameter of the glenoid, improving joint stability.¹⁵
The long head of the biceps functions to depress the humeral head and serves as an adjunct anterior stabilizer of the shoulder.¹²,¹⁴
Disruption of the biceps anchor and the superior labrum, as seen in type II SLAP tears, can result in glenohumeral instability.
The most common mechanisms for SLAP tears include forceful traction loads to the arm, direct compression loads, and repetitive overhead throwing activities.¹⁷ Direct traction injury to the biceps tendon has also been linked with SLAP tears.⁴
- However, there is evidence that up to a third of patients with SLAP lesions have no preceding trauma.²⁰
Snyder’s original classification of SLAP tears is most commonly used.²⁵
- Type I: fraying of superior labrum with intact biceps anchor
- Type II: detached superior labrum and biceps anchor
- Type III: bucket-handle tear of superior labrum with intact biceps anchor
- Type IV: bucket-handle tear of superior labrum with extension into the biceps tendon
Snyder’s classification has been expanded to reflect associated injury to the anterior labrum and other structures.¹⁸

NATURAL HISTORY

Conservative nonoperative treatment of SLAP tears is usually unsuccessful.
Simple débridement of unstable SLAP tears (type II and IV) is generally not recommended because the results are poor.⁸

PATIENT HISTORY AND PHYSICAL FINDINGS

Traction and compression are the two primary mechanisms of injury for SLAP tears.
A SLAP tear should be considered in a patient with a history of a traction or compression injury with persistent mechanical symptoms such as catching or locking.
Several clinical tests have been described that focus on the examination of the biceps tendon anchor on the superior glenoid. The Speed, Yergason, O’Brien, and load-compression tests are commonly used.
- Speed and Yergason tests: Pain with the maneuvers suggests a SLAP tear.
- O’Brien test: Pain with downward pressure applied to the internally rotated arm that is relieved with supination suggests a SLAP tear.
- Load-compression test: Painful clicking or popping suggests a SLAP tear.
Type II SLAP tears found in younger patients are commonly associated with instability and a Bankart lesion, whereas type II SLAP tears found in patients older than 40 years of age are often associated with rotator cuff pathology.¹⁶
Although no single clinical test can predictably be used to diagnose a SLAP tear,¹³ the examiner should use all of these tests, along with the history and a high clinical index of suspicion, to make the diagnosis of a SLAP tear.

IMAGING AND OTHER DIAGNOSTIC STUDIES

Although conventional radiographs (anteroposterior and supraspinatus outlet and axillary views) are the standard for initial evaluation of a patient with shoulder complaints, magnetic resonance imaging (MRI) is the most sensitive imaging tool for evaluating the superior glenoid labrum, with a sensitivity and specificity of about 90%.³
The use of contrast arthrography MRI may improve the overall accuracy of MRI for diagnosing SLAP tears.¹⁹
Despite advances in imaging techniques, the gold standard for the diagnosis of a SLAP tear is arthroscopy.

DIFFERENTIAL DIAGNOSIS

NONOPERATIVE MANAGEMENT

Physical therapy is the mainstay of nonoperative treatment of most shoulder injuries.
Selective intra-articular injections with local anesthetic and corticosteroids can be diagnostic and occasionally therapeutic.
The rehabilitation program should focus on achieving and maintaining a full range of motion and strengthening the rotator cuff and scapula stabilizers.
Although physical therapy may be useful for regaining range of motion and strength, most patients with SLAP tears will continue to have symptoms despite physical therapy.

SURGICAL MANAGEMENT

Surgical treatment of SLAP tears should be considered for patients who have persistent symptoms despite appropriate conservative management.
Contraindications for SLAP repair include patients who are high-risk surgical candidates (ie, the risk of anesthetic complications outweighs the possible benefits of successful repair).

Preoperative Planning

Preoperative assessment of glenohumeral instability is paramount to understanding the pathophysiology of a patient’s shoulder complaints.
Associated instability and any other coexisting pathology must also be addressed at the time of SLAP repair.

Positioning

Beach-chair position
Lateral decubitus position
- This may be preferred for cases of suspected labral pathology, especially if associated with posterior instability, because this position allows improved visualization and access with distraction.
- No more than 10 to 15 pounds of traction should be used owing to increased risk of brachial plexus injuries.
- A comprehensive exam under anesthesia should routinely be performed to assess for any instability.

Approach

The primary goal of any SLAP repair is to stabilize the biceps anchor and address any coexisting pathology.
After a thorough diagnostic evaluation, SLAP lesions are treated according to Snyder²⁵ (see the Techniques section).
- Standard anterosuperior and anteroinferior portals are established.
- Accessory portals may also be established depending on the location of the SLAP tear.