The thick tissue band that forms a rim on the shoulder socket is called the labrum. It works to stabilize the shoulder joint and keep key elements in place.
What is the labrum?
The ball at the head of the arm bone (humerus) fits into a shallow cup in the shoulder blade known as the Glenoid socket. The labrum is a fibrous tissue ring that sits on the rim of the socket and increases its depth, helping to hold the ball in place. Various ligaments around the joint attach to specific points of the labrum further stabilizing the joint.
Traumatic injuries,such as falling on an outstretched arm, a sudden jerk or pull when picking up a heavy object, a direct blow to the shoulder, or an abrupt overhead reach usually sustained when trying to prevent a fall, can cause the labrum to tear. Repetitive shoulder motions can also eventually leadto labrum tears.
Once the labrum is torn, it repositions as it heals, which may result in joint instability.
The bicep muscle attaches to the labrum via a small tendon that runs from the muscle through a narrow opening in the rotator cuff tendons. Once inside the joint, the slim biceps tendon attaches to the bone near the joint socket and to the labrum. Extensive labrum tears may also involve the tendon.
Complete labrum tears are injuries that cause the entire labrum to detach from the bone. This type of injury is usually due to a traumatic injury that has resulted in dislocation or subluxation of the shoulder joint.
SLAP – an acronym for superior labrum anterior and posterior – injuries are tears that occur at the top of the labrum where the biceps tendon attaches. SLAP tears involve both the front and back of the attachment point and may also affect the biceps tendon.
Tear injuries that occur below the middle of the socket and involve the inferior glenohumeral ligament are known as Bankart lesions or tears. These injuries commonly happen with shoulder dislocations.
Diagnosing labrum tears
Labrum tears are difficult to diagnose through physical examination and tears to the soft tissue rim are not visible on standard x-ray. Magnetic resonance imaging (MRI) and CT arthrograms – CAT scans performed following an injection of dye into the shoulder – can identify some labrum tears. Still many rim injuries cannot be visualized on these tests.
The best way to diagnose labrum tears is through arthroscopy, a surgical procedure used to diagnose and treat joint problems.
Treatment of labrum tears
Not all labrum tears require surgical repair. Conservative treatment measures including anti-inflammatory medications and physical therapy to increase muscle strength. If further treatment is needed, the next step is often arthroscopic surgery. Sometimes an open surgical technique is used instead of arthroscopy.
During the arthroscopic procedure, tears to the rim are repaired.If the tear extends to the biceps tendon, the tendon is also repaired and reattached, as necessary.
If there is joint instability, surgical techniques to tighten the socket may be needed.
Recovery after labrum surgery
Physical therapy is important after surgical repair, starting with passive range-of-motion exercises. An arm sling is also needed for up to a month after surgery to support the healing shoulder joint.
Exercise is gradually increased as the shoulder heals. With appropriate rehabilitation, recovery is usually complete within approximately 4 months.