The shoulder joint is formed by the humerus (upper arm) and the glenoid labrum of the scapula (shoulder blade). The relative size of these two structures is analogous to a golf ball (head of the humerus) on a golf tee (glenoid). This makes the shoulder joint have a large range of motion and explains why we can put our arms over our heads or scratch the middle of our back.
This large range of motion also can lead to injuries. One type is the SLAP lesion. The labrum deepens the golf tee to help make the shoulder more stable. The biceps tendon attaches at the top of the labrum. SLAP is an acronym for Superior Labrum Anterior to Posterior. This describes the way the labrum tears.
One theory about the tear is that it results when the shoulder joint tries to dislocate. The biceps tendon contracts to prevent the dislocation and distracts the glenoid labrum. As the shoulder “slides back” the head of the humerus clips the distended labrum resulting in a tear. This can be exhibited by a football player who lands on their outstretched arm while being tackled.
A second theory centers around repeated stress. For example, the repeated stress of overhead throwing. As a baseball and softball player, or quarterback throws the ball, the superior labrum is under high amounts of stress. Especially during the deceleration phase after ball release.
Evaluating this injury can be difficult. One of the most important pieces of the evaluation is the history of the injury. Was the athlete a thrower? Did he/she feel or hear a “pop” with one specific throw? Did they fall on their outstretched arm? Has the ability to throw gotten worse? Does the shoulder “catch” or “click” during overhead activities?
If the answer to these questions are “yes,” then a SLAP must be considered. A referral to an orthopaedic surgeon who deals with sports injuries should then be considered.
The physician may use a series of diagnostic tests to determine if the labrum is torn. These may include: the anterior slide test (a), O’Brien test (b), and the crank test (c). The doctor may also order an MRI to determine the extent of the injury. Keep in mind that none of these tests may elicit a “positive” result. This is the reason the athlete’s history is so important.
Once a SLAP is diagnosed, and surgery scheduled, the surgeon will determine the type of tear. This is done at the time of surgery and dictates the surgical repair.
A type I tear is repaired by a simple debridement of the worn tissue. The surgeon must be sure that the biceps tendon is still securely attached to the labrum.
A type II tear involves the biceps tendon and the labrum. The biceps and labrum are becoming detached from their bed on the glenoid fossa. This injury is treated by “tacking” the labrum and biceps complex down to the glenoid with biodegradable suture anchors.
A type III tear is similar to a bucket handle tear of a knee meniscal cartilage. The labrum/biceps complex is stable on the glenoid but a flap of tissue is hanging down into the joint. This is treated with surgical excision of the flap. There is some debate about repair v. excision; some surgeons will repair if the tear involves 1/3 or more of the labrum.
A type IV tear is complex and involves the labrum and biceps tendon. The labrum presents with a bucket handle type tear that extends into the body of the biceps tendon. The treatment for this complex tear is complex as well. If the biceps tendon/labrum complex is stable on the glenoid, the labral tear will be removed and the biceps tendon repaired. If the complex is unstable on the glenoid the surgeon will use suture anchors to secure the labrum/biceps complex. The biceps tendon will be repaired with suture.
Rehabilitation is relative to the repair procedure. If debridement was the surgical treatment, rehabilitation will begin when the athletes pain allows. If there was repair of either the biceps or glenoid, rehabilitation will start in approximately 4-6 weeks. The labrum or biceps must scar down and begin to heal so that the stress of rehabilitation does not re-injure the athlete.