From the Guidelines
A SLAP lesion is typically caused by acute trauma or repetitive overhead motions that stress the shoulder joint, with the primary causes including acute trauma, repetitive overhead motions, sudden forceful pulling, and age-related degeneration. The mechanism involves excessive force or stress on the superior labrum where it attaches to the biceps tendon, which can cause the labrum to tear or separate from the glenoid (socket) of the shoulder joint 1.
Causes of SLAP Lesions
- Acute trauma: Falling on an outstretched arm or a direct blow to the shoulder can cause a SLAP lesion, as noted in the context of traumatic shoulder pain 1.
- Repetitive overhead motions: Common in athletes who participate in sports like baseball, tennis, or swimming, as well as workers who frequently perform overhead tasks.
- Sudden forceful pulling: Such as when trying to lift a heavy object or during rapid deceleration of the arm.
- Age-related degeneration: Natural wear and tear of the labrum over time can contribute to SLAP lesions, especially in older adults.
Importance of Understanding Causes
Understanding these causes is crucial for prevention, especially for athletes and workers in high-risk occupations. Proper technique, strength training, and avoiding overuse can help reduce the risk of developing a SLAP lesion. The diagnosis and evaluation of SLAP lesions can be aided by imaging techniques such as MRI, MR arthrography, and ultrasound, which are considered equivalent in evaluation, depending on local expertise 1.
Diagnostic Approaches
- MRI shoulder without contrast: Rated 9 for its appropriateness in evaluating shoulder pain, including SLAP lesions 1.
- MR arthrography shoulder: Also rated 9, with the ability to distend the joint and outline labral and capsular structures, aiding in the diagnosis of SLAP lesions 1.
- Ultrasound shoulder: Operator-dependent but useful for evaluating the acromioclavicular joint, tendons of the rotator cuff, and the long head of biceps tendon, with a rating of 9 for its appropriateness 1.
From the Research
Causes of SLAP Lesions
- Repetitive overhead motion is a common cause of SLAP lesions, particularly in overhead athletes 2, 3, 4
- Falls on an outstretched arm can also lead to SLAP lesions 3, 5, 4
- Compression forces to the shoulder, such as those experienced in a fall, can cause SLAP lesions 5
- Overuse, such as from repetitive baseball pitching, can also contribute to the development of SLAP lesions 6
Mechanisms of Injury
- The mechanism of injury for SLAP lesions often involves a combination of factors, including repetitive motion, trauma, and compression forces 2, 3, 5
- The injury typically occurs when the shoulder is positioned in abduction and slight forward flexion, such as when throwing or falling onto an outstretched arm 5