SLAP and Labral tears
The shoulder is the most mobile joint in the body and as such, a complex arrangement of structures is required to stabilise the shoulder during movement. Unfortunately, these structures can be prone to injury and this can influence the stability of the shoulder.
The glenoid (shoulder socket) is a very flat cup and as such, it is inherently unstable. To deepen the shoulder socket, the glenoid has a rim of fibrous cartilage all the way around its periphery therefore deepening the socket. This helps provide some stability but it is further reinforced with the aid of the shoulder capsule. There are also ‘condensations’ of tissue within the capsule that make up the ligaments of the shoulder. These ligaments also contribute to shoulder stability.
If a shoulder dislocates, an injury to the labrum can occur. The nature of the injury usually takes the form of a labral tear, where the labrum becomes detached from the bony rim of the gleonid. If the labral tear occurs at the upper most part of the glenoid it is termed a SLAP (Superior Labrum Anterior and Posterior) tear. Although a SLAP tear can occur following a dislocation type event, it can also occur secondary to a forceful rotatory movement of the shoulder. This type of movement can pull on the Long Head of Biceps (LHB) Tendon, which in turn, merges with the labrum at the upper most part of the shoulder socket. The LHB can therefore cause a detachment of the superior labrum from the glenoid resulting in a SLAP tear. Overhead athletes are particulay prone to SLAP injuries.
SLAP tears have been classified by Synder based on the nature of the tear;
- Type I; Frayed but without any true detachment. This is often a degenerative condition affecting many middle aged or elderly patients
- Type II; Traumatic detachment of the biceps anchor
- Type III; Longitudinal midsubstance tear of the superior labrum that forms a bucket-handle tear
- Type IV; Midsubstance tear of the superior labrum, which extends into the substance of the biceps tendon.
- Type V; Midsubstance tear which extends anteriorly into a Bankart lesion (Maffet classification)
Labral tears can also come in a variety of lesions. They include;
- Perthe’s Lesion; a minimal labral tea
- Bankart tear; a more significantly detached labrum.
- Bony Bankart lesion; a detached labrum associated with a fracture to the glenoid rim.
- ALPSA lesion (Anterior Labral Periosteal Sleeve Avulsion). This is a labral tear that also strips off the thick lining to the bony neck of the glenoid.
- Pain; can be caused by the event of a subluxation or dislocation which occurs as a result of the damage to the labrum resulting in instability. Minor instability can also result in too much movement of the ball across the socket, which in turn can result in shoulder impingement pain. A SLAP tear can however also have very specific symptoms of pain or clicking which is especially evident when the arm is taken across the chest and rotated.
- Subluxation; can occur when a shoulder partially dislocates, but then spontaneously relocates. This can result in a painless or painful clunk.
- Dislocation; the shoulder completely dislocates and remains in a dislocated position for a variable amount of time. This often results in pain, although pain may become less after multiple dislocations.
- Apprehension; one can often sense when the shoulder is about to dislocate. This can result in apprehension, such that the arm is used in more a more limited way for fear of dislocating the shoulder.
Causes & Risk factors
There are numerous causes and risk factors for labral injuries. The more common ones include;
- Contact sports
- Repetitive overhead sports or activities are particular risk factors for a SLAP tear.
The diagnosis of shoulder labral tear instability is made clinically following a history and examination.
Imaging can is however very helpful in confirming the diagnosis.
- MR arthrogram; is ideal for looking at the integrity of the labral tissues. Just before the MRI is undertaken, contrast is injected into the shoulder that then highlights any labral detachment.
There are a number of treatments available for recurrent instability, however the treatment has to be specific for the nature of the instability. The options include;
- Physiotherapy; exercises to improve core strength, the shoulder blade position as well as the strength of the rotator cuff are all important in optimising the muscles that aid shoulder stability. However, as a labral tear is a structural lesion, this may have limited benefit.
- Injections; if the long head of biceps (LHB) tendon is made unstable following a SLAP tear, it can move inappropriately within the bicipital groove. This can result in inflammation around the LHB tendon, particularly as it travels through the biciptal groove as it exits the shoulder. In such cases, an injection around the tendon can prove helpful however as this is a structural lesion, it might not prove helpful in the long term.
- Arthroscopic SLAP repair(labral repair); this is undertaken as an arthroscopic (key-hole) procedure in which the torn labrum is sutured back to the glenoid rim. An arthroscopic labral repair can be performed as a ‘key-hole’ procedure through 3 or 4 small incisions. A sling or brace is used to support the shoulder for 4-6 weeks thereafter.
- Biceps tenodesis: SLAP repairs in the younger patient tend to give good results however older patients can be more prone to post-operative stiffness. To avoid this risk, a biceps tenodesis can be undertaken. In this procedure the biceps tendon is detached from the superior glenoid rim and fixed into the bicipital groove, located just outside the shoulder. By removing the LHB from its position within the shoulder, further biceps aggravation can be avoided, especially during twisting movements of the shoulder and arm.