Labral (SLAP) Tears of the Shoulder

UW Health's Sports Medicine doctors treat a wide range of common athletic injuries, including labral tears of the shoulder (SLAP, or Superior Labrum Anterior and Posterior).


Anatomy of the Shoulder


The term SLAP stands for Superior Labrum Anterior and Posterior. The labrum is a fibrocartilaginous cup-like structure that surrounds the glenoid rim of the scapula (shoulder blade) which makes up part of the shoulder joint. The outside areas of the labrum are thick but the inner regions are much thinner. The biceps tendon attaches to the superior labrum at the top of the glenoid. The glenoid labrum is divided into four sections:

  • Anterior: Front portion that is thicker than the rest of the labrum and is attached both centrally and peripherally to the glenoid fossa
  • Superior: Top portion that is a meniscus-like structure with a central free edge that has no blood supply and also has a looser attachment on the glenoid fossa
  • Posterior: Back portion that is not always attached to the glenoid, which may explain why some people complain of more shoulder pain in the back of their shoulder
  • Inferior: Bottom portion that is triangular in shape and attached at the central edge of the fossa

The areas between the anterior labrum and the superior labrum contain a limited blood supply while the inferior labrum has good blood supply. The outside areas of the labrum have more blood supply than the central portion. Since blood supply greatly improves the ability for tissues to heal, areas of the labrum with poor blood supply do not heal well.


Function of the Labrum


The labrum has several functions. It:

  • Expands the depth of the glenoid fossa by approximately 50 percent to allow for increased motion
  • Optimizes shoulder mechanics by centering and stabilizing the upper arm (humerus) as it moves on the scapula (glenoid)
  • Prevents the humeral head (located on the upper arm at the shoulder joint) from rolling over the edge of the scapula (at the glenoid) since the labrum is thicker towards the outside edges

Possible Causes for Labral Injuries


The labrum may be injured in several ways, including:

  • Compression force (falling on an outstretched arm)
  • Traction force (shoulder dislocation)
  • Direct blow or trauma to the shoulder
  • Repetitive motion (overhead activities like throwing and swimming)
  • “Peel back” mechanism, which occurs when the shoulder externally rotates and an upper arm muscle (the long head of the biceps) tears (or “peels back”) the labrum

Signs and Symptoms


The signs and symptoms of a labral tear include:

  • Insidious onset (no known event that caused the injury)
  • Periodic or continuous pain
  • Variable pain that may be dull, achy or sharp
  • Pain that extends down the outside of the upper arm
  • Pain with shoulder external rotation
  • Popping, clicking, locking or snapping that is felt deep in the shoulder joint
  • Decreased arm strength and/or flexibility
  • Shoulder instability

Diagnostic Imaging


An MRI arthrogram (also called an MRA) is the most accurate diagnostic test to identify SLAP lesions with an accuracy rate of 74 to 90 percent.


Treatment Options


Several treatment options may be used with SLAP lesions, including:

  • Rehabilitation: Often times rehabilitation is not successful, especially with athletes who perform repetitive overhead activities
  • Surgery: The labrum is repaired arthroscopically and a biceps tenodesis or biceps tenotomy may be performed as well to assist with functional improvement and return to play

Return to Play Time Frame


The time frame and ability for athletes to return to play is variable (approximately 48 - 98 percent return to play), but general criteria include:

  • Waiting up to 12 months after surgery for full return to play for athletes participating in sports that require a lot of overhead activities
  • Throwers: Sstudies report a return to play success rate (achieving pre-injury activity level or better) of 38 percent and higher
  • Non-throwers: Studies report a return to play success rate (achieving pre-injury activity level or better) of 89 percent
  • Athletes participating in contact sports may return to play within six months