Abstract
The glenoid labrum is a densely fibrous tissue that is located along the periphery of the glenoid portion of the scapula. It functions to provide increased stability, while still allowing great range of motion. In addition, it serves as an attachment point for tendons and ligaments. Tears can occur in all regions of the labrum. The two most common sites include the superior labral anterior-posterior (SLAP) tear, occurring with forced traction of the shoulder and/or direct compression, and the Bankart lesion, created by episodes of anterior instability. Symptoms of deep-seated pain (SLAP tears) or anterior instability (Bankart lesions) are the most common presentations, but concomitant shoulder pathology makes diagnosis challenging and clouds many physical exam findings. Physical exam includes several clinical tests, with the O’Brien’s test being the most common for SLAP tears and the surprise test as the most accurate for Bankart lesions. As in any case of shoulder pain, the initial imaging of choice is plain radiography. With a high clinical likelihood of labral disease, this should be followed by either magnetic resonance imaging or magnetic resonance arthrography. Initial management of SLAP tears involves exhausting non-operative treatment, focusing on stretching and strengthening of the dynamic shoulder stabilizers. Initial management of Bankart lesions (after reduction) may be conservative or operative and depends on demographic and radiographic factors. Surgical management of SLAP tears are reserved for those who have failed conservative management. Operative treatment of Bankart tears are reserved for those with recurrent instability despite conservative treatment.
Keywords
Anterior Instability, Bankart Lesion, Glenoid Labrum, Shoulder Dislocation, SLAP Tear
| Synonyms | |
| |
| ICD-10 Codes | |
| S43.431 | SLAP lesion of right shoulder |
| S43.432 | SLAP lesion of left shoulder |
| S43.439 | SLAP lesion of unspecified shoulder |
| M75.80 | Other shoulder lesions, unspecified shoulder |
| M75.81 | Other shoulder lesions, right shoulder |
| M75.82 | Other shoulder lesions, left shoulder |
Definition
The glenoid labrum is a densely fibrous tissue that is located along the periphery of the glenoid portion of the scapula ( Fig. 15.1 ). As the outer labrum transitions from the periphery to its articulation with the glenoid, the histology changes from fibrous to a small fibrocartilaginous zone at the junction with the glenoid articular cartilage. The labrum increases the height and width of the glenoid while also giving extra depth to the joint. This provides increased stability while still allowing great range of motion. The labrum also serves as an attachment point for the long head of the biceps tendon, the glenohumeral ligaments, and the long head of the triceps tendon, forming a periarticular system of fibers that gives the shoulder joint much needed stability. The vascular supply to the labrum is from the posterior humeral circumflex artery, the circumflex scapular branch of the subscapular artery, and the suprascapular artery. These arteries come from the periphery of the labrum, making the articular margins of the labrum avascular. It has also been shown that the superior labrum has less vascular supply than the inferior labrum. The long head of the biceps tendon has a variable attachment to the labrum and glenoid. Approximately 40% to 60% of biceps tendons originate from the supraglenoid tubercle, and the remaining fibers insert into the labrum. The biceps insertion into the labrum is variable, but most commonly is in a more posterior position.
Tears can occur in all regions of the labrum. The most studied injury to the labrum is the superior labral anterior-posterior (SLAP) tear. Anterior dislocations of the shoulder can be associated with a disruption of the anteroinferior labrum and anterior band of the inferior glenohumeral ligament, also known as a Bankart lesion. Posterior shoulder instability may result in injury to the posterior band of the inferior glenohumeral ligament as well as the posterior labrum, or a reverse Bankart lesion. Tears can extend to involve multiple regions of the labrum and have other associated injuries. The SLAP tear and Bankart lesion are the most common pathologies seen and for that reason are the focus of this discussion.
The most common mechanisms for SLAP tears are forced traction on the shoulder and direct compression. Direct compression can occur in the acute traumatic setting or in the chronic setting typical in the overhead-throwing athlete. Overhead throwers are predisposed to SLAP tears secondary to their adaptive anatomy. They tend to have posterior capsular contractures, loose anterior capsular structures, and a retroverted humeral head, all increasing the amount of external rotation in the shoulder. As a result of these anatomic changes, the arm goes into an extreme externally rotated position while the biceps kinks at its insertion and assumes a more vertical and posterior position. This applies a torsional force to the biceps-labral complex superiorly, resulting in a peel-back mechanism on the superior labrum. Alternatively, as throwers externally rotate in the cocking phase, the rotator cuff may impinge on the posterosuperior glenoid, causing an “internal impingement” and tearing of the labrum. Although SLAP lesions are more common in overhead athletes, they also occur in contact sports. A recent study looking at SLAP lesions in professional football players found that offensive linemen have the highest rate of injury when compared to other positions; this is most likely due to the increased contact that is undertaken by this position.
Classically, SLAP tears are classified into four types, which can then be further modified. Most physicians think that the four-class system ( Fig. 15.2 ) is sufficient and that the additional classifications could be placed within these basic types, so it is the preferred classification.
Bankart lesions are created by episodes of anterior instability. As the humeral head moves out anteriorly and inferiorly, anterior damage can occur to the anteroinferior labrum, glenohumeral ligaments, joint capsule, rotator cuff, and possibly neurovascular structures. It has been demonstrated that the Bankart lesion is created about 85% to 97% of the time in anterior dislocations. This pathologic change is thought to be an important reason for recurrent instability.
In addition to increasing the depth and diameter of the glenoid, the labrum and capsule also create a negative pressure that provides stability through the glenohumeral articulation. If the labrum or capsule is injured, such as in the Bankart lesion, this suction seal is lost, and this decreases the stability of the shoulder. Several factors may predispose patients to recurrent instability. These include fracture on the glenoid (bony Bankart) or humeral head (Hill-Sachs lesion), hyperlaxity syndromes, male gender, younger age at initial dislocation, participation in contact or overhead throwing sport, and positive correlation between number of dislocations and risk of future dislocation. Dislocations later in life increase the risk of rotator cuff injury, with tears occurring in nearly 30% of patients older than 40 years and in up to 80% of patients older than 60 years.
Symptoms
Superior Labral Anterior-Posterior Tear
A patient with a SLAP tear will most commonly present with symptoms of deep-seated pain, which can be sharp or dull. It is usually located deep within the center of the shoulder and can be made worse with overhead activities, pushing heavy objects, lifting, or reaching behind the back. Patients may have mechanical symptoms, such as catching, popping, or grinding with rotation of the shoulder. One study found that in 139 patients demonstrating a SLAP lesion on shoulder arthroscopy, 123 patients (88%) also had other intra-articular lesions, making clinical diagnosis challenging.
It is essential to obtain a thorough history for trauma to evaluate for traction or compression type injuries, dislocations, and sports (e.g., baseball, football, waterskiing, and tennis) they play that may predispose them to this injury. Overhead throwing athletes may suffer decreased velocity and usually complain of pain in the late cocking and early acceleration phase of throwing. They may have weakness due to pain or secondary to a paralabral cyst compressing the suprascapular nerve. Compression on the nerve at the spinoglenoid notch can cause weakness in external rotation as well as deep posterior shoulder pain.
Bankart Lesion
Symptoms of anterior instability are usually obvious, as the patient states that there has been a dislocation and continues to complain of pain or instability in that shoulder. Sometimes there is not a history of overt dislocation, but instead the patient has multiple episodes of instability without a complete dislocation. The patient will complain of pain and feeling of impending dislocation with the arm in abduction and external rotation. Important historical variables include the patient’s age at first dislocation, need for formal reduction, number of recurrent instability episodes, voluntary instability, and anticipated future sports activities.
The most comfortable position for these patients is usually with the arm in adduction and internal rotation. They avoid abduction and external rotation because this is the position that led to the dislocation and it also stresses the injured labrum, inferior glenohumeral ligament, and subscapularis tendon.
Physical Examination
Superior Labral Anterior-Posterior Tear
Several clinical tests are designed to assist the clinician in making the SLAP tear diagnosis. These tests aim to do one of two things: to pinch the torn labrum between the humeral head and the glenoid, causing pain or mechanical symptoms, or to place traction on the biceps tendon ( Table 15.1 ). The tests have had variable ranges of sensitivity and specificity between studies, and thus no single test is considered diagnostic. The most commonly performed test is the O’Brien’s active compression test. This has been shown to be very sensitive, but has poor specificity. Accurate diagnosis requires a careful history to correlate with the examination findings.
| Test | Instruction | Indication of Positive Test Result |
|---|---|---|
| Active compression (O’Brien) test | Arm is forward flexed to 90 degrees, adducted across the body Patient resists downward force on arm in pronated and supinated position of the forearm | Pain is increased in pronated position |
| Crank test | Arm is abducted > 100 degrees in the scapular plane; elbow is flexed to 90 degrees Axial force is applied through the humerus onto the glenohumeral joint and the shoulder is rotated (internal and external rotation) | Pain, catching, clicking |
| Pain provocative test | Patient abducts shoulder to 90 degrees, flexes elbow to 90 degrees, and pronates and supinates the hand | Pain is worse or present only in pronation |
| Biceps load test | Patient is supine; shoulder is abducted to 90 degrees; elbow is flexed to 90 degrees The shoulder is externally rotated to a point at which the patient feels pain, apprehension, or maximum external rotation; the patient then performs resisted flexion of the elbow | Worsening of pain when resisted elbow flexion is performed |
| Compression-rotation test | Patient is supine; shoulder is abducted to 90 degrees; elbow is flexed to 90 degrees Axial load is placed on the glenohumeral joint and the humerus is rotated | Pain, catching, clicking, snapping |
| Anterior slide test | Patient is sitting and places hands on the hips with thumbs facing posterior The examiner places a finger over the anterior shoulder and the other hand pushes up on the humerus superior and anterior; patient is asked to resist | Pain or click |
In many cases, concomitant disease may cloud the physical examination findings. On inspection of the shoulder, there may be atrophy of the supraspinatus and infraspinatus muscles. The supraspinatus atrophy is difficult to observe because of the overlying trapezius muscle. The atrophy can occur because of a paralabral cyst that compresses the suprascapular nerve, or it could be secondary to an associated rotator cuff tear. Palpation of the biceps tendon may demonstrate tenderness within the bicipital groove. The range of motion of the shoulder should be preserved, although throwing athletes may have increased external rotation and loss of internal rotation with a resulting glenohumeral internal rotation (GIRD) deficit.
Bankart Lesion
Evaluation for anterior instability may include a number of tests ( Table 15.2 ). After reduction of a dislocation, a thorough neurovascular examination should be performed to rule out major vessel or brachial plexus injury. In a typical Bankart lesion with anterior instability, patients will often experience apprehension when the arm is brought into abduction and external rotation. Strength should be assessed, looking for axillary or radial nerve palsies as well as rotator cuff disease in the older patient. In a patient older than 40 years who cannot lift the arm after a dislocation, rotator cuff tear is far more common than an axillary nerve palsy. The surprise test has been shown to be the most accurate test, with a positive predictive value of 98% and a negative predictive value of 78%.
| Test | Instruction | Indication of Positive Test Result |
|---|---|---|
| Load and shift | Supine position Arm at 0, 45, 90 degrees of abduction Anterior directed force on the humerus | Increasing translation at higher degrees of abduction indicates that the inferior glenohumeral ligament is compromised Grade 1: increased translation compared with contralateral Grade 2: humeral head translates to the glenoid rim Grade 3: translates over the glenoid rim |
| Apprehension test (crank) | Supine position Arm brought into 90 degrees of abduction and increasing external rotation | Pain, feeling of impending dislocation, or muscle guarding |
| Relocation (Jobe) test | Apprehension position with posteriorly directed force on the humeral head | Decreased apprehension or pain |
| Surprise test | Relocation test with sudden release of posteriorly directed force | Sense of instability or apprehension with release of force |
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