The shoulder is made up of three bones: the scapula (shoulder blade), the humerus (upper arm bone), and the clavicle (collarbone). A part of the scapula, called the glenoid, makes up the socket of the shoulder. The glenoid is very shallow and flat, much like the tee in the golf ball analogy used earlier in the articles—so the shoulder joint would be relatively unstable except for the labrum, a rim of soft tissue that makes the socket more like a cup.
The labrum adds stability and is exposed to a significant amount of stress. It is not surprising, then, that this rim often develops tears, particularly on the top part (or “superiorly”) —hence the acronym SLAP (“superior labrum anterior posterior” tear). If the tear is extensive it may even cause a flap of tissue to move in and out of the joint, getting caught between the head of the humerus and the glenoid (in much the same way that a rug gets caught under a door). The flap can cause pain and a catching sensation when you move your shoulder. And because the biceps tendon (which originates in the big muscles on the front of your upper arm) and several ligaments attach to the labrum, when the labrum tears the shoulder often becomes less stable.
Sports can cause injuries to the labrum when the biceps tendon pulls sharply against the front of the labrum. Baseball pitchers are prone to labral tears because the action of throwing causes the biceps tendon to pull strongly against the top part of the labrum; weightlifters can have similar problems when pressing weights overhead. Golfers, too, may tear their labrum if their club strikes the ground during the golf swing, and volleyball players can injure their labrum when spiking a ball.
Other causes of labral tears include a fall on an outstretched hand that drives the humerus forcefully upward into the labrum, and a sudden and often unexpected load applied to the biceps, which adds undue stress on the labrum.
The main symptom of a labral tear is a sharp pop or catching sensation in the shoulder during certain shoulder movements. Although there may be a mild ache for several hours, the tear may not cause pain. In fact, any pain that you may feel is usually caused by inflammation of the capsule of the shoulder. Every time you move in a way that causes the labrum to flip back and forth, irritation and inflammation of the capsule occur. (For example, patients will often complain of pain when they try to reach into the back seat of a car while seated in the front.)
Your doctor may suspect a labral tear based on how you injured your shoulder, so be ready to provide details about your most recent injury as well as information about any past damage to the area. In addition, he or she will conduct a physical examination and may challenge the shoulder with movements that can bring on the symptoms of a possible labral tear, perhaps raising the arm to see if you feel a catching sensation, or holding your arm briefly overhead to see if you experience pain when the shoulder is in that position.
Labral tears are difficult to see, even on an MRI, so doctors sometimes request an MRI arthrogram, in which dye is injected into the shoulder prior to performing the MRI in order to make the labrum more visible.
Your doctor’s first goal will be to control your pain and inflammation, so your initial treatment recommendation will likely be rest and antiinflammatory medication such as acetaminophen or ibuprofen, as well as noninvasive techniques such as heat or ice. If anti-inflammatory medication doesn’t control your pain, your doctor may suggest a cortisone injection (see this for details on these injections).
Rehabilitation will also be important, and your doctor will probably have a physical therapist direct your rehabilitation program. Hands- on manipulation of the muscles as well as various types of exercises will be employed to improve your range of motion in the shoulder and the nearby joints and muscles. Later in your recovery and treatment you will undertake strengthening exercises to improve the strength and control of the rotator cuff and shoulder blade muscles. Your therapist will assist you as you retrain these muscles to keep the ball of the humerus in the glenoid; doing so will improve the stability of your shoulder and help it move smoothly during all of your activities.
If you don’t respond to conservative therapy, you may need surgery. Fortunately, the arthroscope can be used to treat many labral tears. If the tear is small and for the most part gets caught only as you move the shoulder, simply removing the frayed edges and any loose parts of the labrum (a process known as debridement) may get rid of your symptoms.
If the tear is larger, the shoulder may also be unstable. In this case, the labral tear may need to be repaired rather than simply removed. Several new techniques allow surgeons to place small anchors into the socket to help tack the labrum back down arthroscopically.