Sunday, November 20, 2011

Type of SLAP lesions & The dead arm syndrome




The SLAP lesions:
Superior labrum tears were first described by Andrews. Further SLAP lesions as described by Snyder are subdivided into 4 types (I-IV) & this classification is according to their severity of tear. For best diagrams of the SLAP lesions refer to the following site:

http://www.shoulderdoc.co.uk/article.asp?article=1027

Type I SLAP lesion:
This is a partial tear and degeneration to the superior labrum, where the edges are rough and fray along the free margin, but the labrum is not completely detached.
Type II lesion:
Type II is the comonest type of SLAP tear. The superior labrum is completely torn off the glenoid, due to an injury (often a shoulder dislocation). This type leaves a gap between the articular cartilage and the labral attachment to the bone. Type 2 SLAP tears can be further subdivided into (a) anterior (b) posterior, and (c) combined anterior-posterior lesions.
Type III lesion:
A Type III tear is a 'bucket-handle' tear of the labrum, where the torn labrum hangs into the joint and causes symptoms of 'locking' and 'popping' or 'clunking'. 

Type IV lesion:
The Type IV SLAP tear is one where the tear of the labrum (bucket handle tear) extends into the long head of biceps tendon.

Dead arm syndrome (DAS) &; Type II SLAP lesion:

Now the most important part of the article is which of the SLAP lesion presents with “Dead arm syndrome”.
Dead arm syndrome is clearly a subjective phenomenon (see the definitions below). The sufferer is mostly an athlete whose work involves lot of throwing for example base ball or cricket. The athlete will often say "I just can't throw anymore, and / or the shoulder just doesn't feel right". This type of injury tends to progress gradually over time, slowly creeping up on the overhead athlete until severe pain and subjective instability limits his or her ability to perform.

Dead arm syndrome: Definition

1. Sensory diminution or loss in the arm after anterior shoulder dislocation or subluxation. (Stedman's medical dictionary)

2. The Dead Arm Syndrome has been defined as the inability to throw, spike or serve at pre-injury level secondary to subjective pain and instability.

Description & progression of DAS:

Dead arm syndrome starts with repetitive motion and thus force exerted on the posterior capsule of the shoulder. Overuse can lead to posterior capsule hypertrophy. The next step is tightness of the posterior capsule called posterior capsular contracture. This reduces the shoulder internal rotation. If shoulder activities are still continued then over time, with enough force, a tear may develop in the labrum. The shoulder is unstable and dislocation may come next. Dead arm syndrome won't go away on its own with rest—it must be treated. If there's a SLAP lesion, then surgery is needed to repair the problem. If the injury is caught before a SLAP tear, then physical therapy with stretching and exercise can restore it. Before hand how to know then a SLAP lesion or a dead am syndrome may occur? The answer is shoulders at risk for the dead arm syndrome have a marked loss of internal rotation caused by contracture of the posteroinferior capsule such that less than a 180 degrees arc of rotation is achieved with the arm abducted 90 degrees (the 180 degrees rule).

What is the cause of DAS?
According to Buckhart et al root cause of the dead arm syndrome is the Type II SLAP lesion.
Type 2 SLAP lesions that cause the dead arm syndrome in overhead-throwing athletes are most likely acceleration injuries that occur in late cocking rather than deceleration injuries in follow-through.

More about Type II SLAP lesions form Buckhart et al’s article:

Clinical presentations of all 3 types of Type II SLAP lesion are different. Following are few points to remember about them.
1. Posterior and combined Type 2 SLAP lesions can be disabling to overhead-throwing athletes because of posterosuperior instability and anteroinferior pseudolaxity.
2. The Jobe relocation test is positive with posterosuperior pain in patients with posterior or combined anterior-posterior Type 2 SLAP lesions and is negative in patients with anterior Type 2 SLAP lesions.
3. Rotator cuff tears are frequently associated with posterior or combined anterior-posterior SLAP lesions, are lesion-location specific, and typically begin from inside the joint as undersurface tears.
4. The peel-back mechanism is a likely cause of posterior Type 2 SLAP lesions.

Classification
•    Two categories
o    Aware of subluxation
o    Unaware of subluxation
•    Often misdiagnosed as other shoulder pathology or cervical lesion

Associations with other diseases
•    Thoracic Outlet Syndrome
o    30% of patients had coexistent TOS
o    Due to altered kinetics of the Scapulothoracic Joint
o    Resultant neurovascular compromise

Treatment of DAS:

A. Surgical:
1. Repair of posterior SLAP lesions can return overhead-throwing athletes to full overhead athletic functioning.
2. To securely repair the posterosuperior labrum to resist torsional peel-back, suture anchors must be placed posterior to the biceps at the corner of the glenoid. The repair must be protected against external rotation past 0 degree for 3 weeks to avoid undue premature torsional stresses on the repair from the peel-back mechanism.

B. Physiotherapy:
Rehabilitation of athletes with the dead arm syndrome must include the entire kinetic chain.

Reference:
1. Burkhart SS et al;  Clin Sports Med. 2000 Jan;19(1):125-58.
2. Wikipedia
3. http://www.shoulderdoc.co.uk/article.asp?article=1027
4. http://www.orthofracs.com/adult/elective/shoulder/dead-arm-syndrome.html

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