What are the labrum and biceps and what do they do?
When the shoulder joint is injured, the contents of the joint are at risk. The shoulder joint contains the origin of the long head of the biceps tendon, as well as a cartilaginous structure called the labrum. The labrum functions to help stabilize the joint, preventing excessive motion and dislocation when the shoulder is in a vulnerable position. The biceps tendon and labrum are intimately related inasmuch as an injury to one usually causes injury to the other.
How does someone injure the biceps/labrum?
Two mechanisms of acute injury to the biceps and labrum have been proposed. One way that it may be injured is by falling on an outstretched arm, causing the humeral head to impact into the glenoid and stretching the biceps and labrum to the point of tearing. The other major mechanism is overhead throwing, or tennis/ volleyball serves that result in a near dislocation (subluxation) and stretch the biceps and labrum to the point of tearing. Other mechanisms of injury include chronic overuse and instability with or without a rotator cuff tear. Clearly, the different problems of the shoulder can occur alone or combined.
In this illustration, traction on the biceps can pull off the attachment to the socket (glenoid). A fall on an outstretched arm can injure the biceps/labral attachment. In the illustration to the left, The humeral head (ball) is driven up into the glenoid (socket) causing the biceps and labral attachments to tear off.
How is a biceps/labral tear diagnosed?
The patient with a biceps / labral lesion usually complains of anterior arm pain, possibly in the region of the biceps tendon as it exits the shoulder joint.
The torn labrum can predispose the patient to recurrent episodes of near dislocation or the feeling that the shoulder may dislocate when it is put in a provocative position. Labral tears can cause clicking, catching, and pain in the shoulder joint.
Physical examination is key to diagnosing labral tears, especially since not all tears are found on MRI scanning.
If a labral tear is suspected, a MRI with contrast injected into the joint is the best test for diagnosing the problem. Although this test is the best for diagnosis, it does not always show a labral tear and if symptoms persist despite a negative MRI, operative treatment may be indicated.
How is a biceps/labral tear treated?
A biceps or labral tear that is causing pain, catching or instability of the shoulder is usually treated with surgery. The surgery can consist of completely arthroscopic treatment or a combination of arthroscopic and open techniques. Depending on the type of tear, it may require repair or simple excision. Sometimes the biceps will be tenodesed, detached from the area that it is torn from and re-attached in a different location on the humerus. Much depends on what is found at the time of surgery.