Classification of slap lesions
Snyder et al. In 1990 first described the classification of slap lesions as types i-iv.
Type i lesions represent a degenerative mechanism characterized by both fraying of the superior glenoid labrum with the peripheral labrum and the biceps anchor still firmly attached to the glenoid. Type ii lesions also show fraying, but the labrum and biceps anchor are stripped from the superior glenoid.
Type iii consists of a bucket-handle lesion of the superior labrum.
Type iv is also a bucket-handle lesion, but there is an extension into the biceps tendon.
Slap lesions are further characterized into 10 subtypes based on associated instability and posterior extension. (maffe et al, powell et al) these are not used in the literature as often as the snyder classification.
Mechanism of injury
A number of mechanisms have been proposed to be the cause of slap lesions.
Bey et al. In 1998 created type ii slap lesions by causing a biceps tendon traction injury from inferior subluxation.
Burkhart and morgan in 1998 proposed the peelback mechanism in baseball players, in which abduction and external rotation cause a rotational force at the biceps tendon; this creates a torsional force that is transmitted through the tendon, peeling the posterior labrum from the glenoid.
Clavert et al. In 2003 used a cadaver model to suggest a shearing mechanism from a fall onto an outstretched hand.
Several studies reported that repetitive overhead throwing is associated with the development of slap lesions (prahan 2001; burkhart 2003; kuhn 2003; shepard 2004)
Clinical diagnosis of slap lesions can be difficult. Patients may complain of anterior shoulder pain, clicking, or a sense of instability. There are multiple physical examination tests described in the literature. Hegedus et al. And parentis et al. Showed no single test had sufficient sensitivity and specificity for the consistent diagnosis of slap lesions. Some examples include:
Active compression test (o’brien 1998)—sensitivity of 67% but specificity was only 37%
Speed test (snyder 1990),
Anterior slide test (kibler 1995),
Crank test (liu 1996),
Yergason test (1931), high specificity (95%) but low sensitivity of 12%
Mri-arthrography has been reported to have a sensitivity as high as 96% and specificity as high as 85%. Hester et al, (2018) concluded that these imaging studies are uniformly poor in differentiating normal age-related deterioration from truly unstable labral lesions, and call into question any mri findings taken in isolation when determining surgical indications. Mri report must be correlated with the patient’s history and physical examination. Even diagnostic arthroscopy gives mixed results in terms of inter-observer and intra-observer reliability (gobezie 2008; jia et al, 2001)
Direct slap repair
This is similar to that of a labral repair commonly performed for treating shoulder dislocations. This involves insertion of suture anchors to the glenoid bone and passing of sutures to tie the labrum back down to the glenoid bone for healing.
This simple procedure involve releasing the long head of the biceps from its end connection with the labrum. At a result it retracts itself outside the shoulder joint and rests at the level of the upper humerus. This ultimately relieves pain by preventing further tension on the injured biceps-labral complex. Advantages of tenotomy include a quick procedural time, adequate relief of pain, and return to activity following surgery. While there is a reported high satisfaction rate following tenotomy in certain patient populations, there may be continued muscle soreness, fatigue in the use of the biceps and cosmetic “popeye sign” appearance of the biceps muscles. This is therefore not indicated in athletes and younger patients
After releasing the long head of the biceps as in the tenotomy described above, the tendon is then attached to a secondary site usually the upper humerus with an anchoring devices or suture anchors. Purported advantages include maintenance of strength, decreased post-operative cramping, preservation of the length-tendon relationship, and improved cosmetic results. Disadvantages include a more complex operation, and similar to slap repair, a longer period of postoperative immobilization and rehabilitation.
Some authors recommend slap repair for patients younger than 35-40 years old and biceps tenotomy or tenodesis for patients older than 35-40 years old (ek et et al 2014; brockmeyer m et al 2016). Others recommend combined slap repair and biceps tenodesis in type ii slap lesions citing that an unrepaired superior labral tear may increase glenohumeral translation. This approach is however not widely adopted.
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