The shoulder joint involves three bones: the shoulder blade (scapula), the collarbone (clavicle) and the upper arm bone (humerus). The head of the upper arm bone (humeral head) rests in a shallow socket in the shoulder blade called the glenoid. Because the head of the upper arm bone is usually much larger than the socket, a soft fibrous tissue rim called the labrum surrounds the socket to help stabilize the joint. The rim deepens the socket by up to 50 percent so that the head of the upper arm bone fits better. In addition, it serves as an attachment site for several ligaments including the biceps tendon.
Injuries to the tissue rim surrounding the shoulder socket can occur from acute trauma or repetitive shoulder motion. Examples of traumatic injury include:
- Falling on an outstretched arm
- Direct blow to the shoulder
- Sudden pull, such as when trying to lift a heavy object
- Violent overhead reach, such as when trying to stop a fall or slide
Throwing athletes or weightlifters can experience tears due to repetitive shoulder motion.
Tears can be located either above (superior) or below (inferior) the middle of the glenoid socket. A SLAP lesion (superior labrum, anterior [front] to posterior [back]) is a tear of the rim above the middle of the socket that may also involve the biceps tendon. A tear of the rim below the middle of the glenoid socket that also involves the inferior glenohumeral ligament is called a Bankart lesion. Tears of the labrum often occur with other shoulder injuries, such as a dislocated shoulder.
Signs and symptoms
It is difficult to diagnose a tear in the shoulder socket rim because the symptoms are very similar to other shoulder injuries. Symptoms may include:
- Pain, usually with overhead activities
- Catching, locking, popping or grinding
- Occasional night pain or pain with daily activities
- A sense of instability in the shoulder
- Decreased range of motion
- Loss of strength
If you are experiencing shoulder pain, your doctor will take a history of your injury. You may be able to remember a specific incident or you may note that the pain gradually increased. The doctor will do several physical tests to check range of motion, stability and pain. In addition, the doctor will request X-rays to see if there are any other reasons for your problems.
Because the rim of the shoulder socket is soft tissue, X-rays will not show damage to it. The doctor may order a magnetic resonance image (MRI) to better assess the soft tissues. A contrast medium may be injected to help detect tears.
Until the final diagnosis is made, your physician may prescribe anti-inflammatory medication and rest to relieve symptoms. Rehabilitation exercises to strengthen the rotator cuff muscles may also be recommended. If these conservative measures are insufficient, your physician may recommend arthroscopic surgery.
During the surgery, the doctor will examine the rim and the biceps tendon. If the injury is confined to the rim itself, without involving the tendon, the shoulder is usually stable. The surgeon will either repair or remove the torn flap and correct any other associated problems. If the tear extends into the biceps tendon or if the tendon is detached, the result is an unstable joint. The surgeon may need to repair and reattach the tendon.
Tears below the middle of the socket are also associated with shoulder instability. The surgeon may reattach the ligament and tighten the shoulder socket by folding over and “pleating” the tissues to tighten the capsule.
After surgery, you will need to use a sling for approximately two-four weeks. Your physician will also prescribe gentle, passive, pain-free range-of-motion exercises. Therapy usually begins after your first post-op visit. They will help you progress your motion and gradually start to strengthen your shoulder and biceps. Athletes can usually begin doing sports-specific exercises after six-eight weeks, although it may be three to six months before the shoulder is fully healed.