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What is a SLAP Tear?

 

A SLAP tear is a Superior Labrum from Anterior to Posterior Tear. The labrum is a special piece of fibrocartilagenous tissue attached to glenoid that depends the shoulder socket and provides stability for the humeral head or upper arm bone. Throwers with shoulder injury commonly describe the feeling of a “dead arm.” A “dead arm” is any pathologic shoulder condition in which the thrower is unable to throw with preinjury velocity and control because of a combination of pain and subjective unease in the shoulder. A SLAP tear is a common injury in overhead athletes. 

 

What causes a SLAP tear?

 

We typically think of SLAP tears affecting overhead athletes, but many people that perform repetitive overhead activities are susceptible to SLAP tears. During the throwing or overhead motion motion, hyper-external rotation leads to abnormal impingement and abrasion damage to the rotator cuff. The hyper-external rotation changes the vector force of the biceps tendon to a more vertical and posterior direction during abduction and external rotation. This vector and subsequent biceps muscle contraction create a torsional force across the posteriorsuperior labrum. Abnormal twisting through the biceps origin on the glenoid leads to torsional overload and shear force injury to the labrum and rotator cuff fibers. The labrum is eventually detached from its anchor as a result of this posterior-superior shift and hyper-external rota- tion: a “peel-back” phenomenon results.

How are SLAP tears treated?

First line treatments involve physical therapy, NSAIDS, rest and activity modification. This is successful for most patients. We try to avoid surgery because it can make the shoulder tighter. Therefore, we will commonly perform a biceps tenodesis (reattach the tendon in a different location) to prevent the biceps tendon from pulling on the labrum and creating pain. In some severely symptomatic young patients they may benefit from arthroscopic repair of the labrum to provide more stability to the joint.

A video demonstrating a SLAP repair surgery can be found here.

A. Normal shoulder position and B. the arm back twisting position. The position of maximal external rotation results in a vector change for the biceps tendon. During overhead movement, the altered vector creates a peel- back mechanism as the biceps tendon pulls on the labral complex. [Reprinted from Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology part I: pathoanatomy and biomechanics. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2003; 19(4): 404–420, with permission from Elsevier

Labrum
Labrum

SLAP Tears

Model of the right shoulder with an arrow pointing at the labrum in the glenohumeral joint of the shoulder. Images courtesy of WikiCommons.

The phases of throwing demonstrate how the overhead motion twists the shoulder and thereby the biceps tendon at its insertion into the labrum. The twisting motion, deceleration motion, and repetitive activity of throwing can lead to a labral tear. Reprinted from Skelley, N.W., Smith M. Prevention of Labral Cuff Injuries in the Overhead Athlete. In John Kelly IV (Ed), Elite Techniques in Shoulder Arthroscopy. Springer. 2016. ISBN 3319251015.

These are arthroscopic surgery images demonstrating the labrum torn and lifted up on the left. On the right, you see a blue suture fixing the labrum back into the anatomic position on the glenoid of the shoulder blade. The humeral head is the large rounded white structure in the top right of the image. Images courtesy of WikiCommons.

References

1. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part I: pathoanatomy and biomechanics. Arthroscopy. 2003;19(4):404-420. doi:10.1053/jars.2003.50128.

2. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology. Part II: evaluation and treatment of SLAP lesions in throwers. Arthroscopy. 2003;19(5):531-539. doi:10.1053/jars.2003.50139.

3. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy. 2003;19(6):641-661.

4. Snyder SJ, Karzel RP, Pizzo WD, Ferkel RD, Friedman MJ. SLAP lesions of the shoulder. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 1990;6(4):274-279. doi:10.1016/0749-8063(90)90056-J.

5. Skelley, N.W., Smith M. Prevention of Labral Cuff Injuries in the Overhead Athlete. In John Kelly IV (Ed), Elite Techniques in Shoulder Arthroscopy. Springer. 2016. ISBN 3319251015.

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