SLAP lesion Flashcards
Definition/Description
A SLAP tear or SLAP lesion is an injury to the glenoid labrum (fibrocartilaginous rim attached around the margin of the glenoid cavity). Tears of the superior labrum near to the origin of the long head of biceps were first described among throwing athletes by Andrews in 1985.The label of ‘SLAP’, an abbreviation for superior labrum anterior and posterior, was coined by Snyder et al, who went on to create a classification system for these lesions.
A total of four types of superior labral lesions involving the biceps anchor have been identified. Type I concerns degenerative fraying with no detachment of the biceps insertion. Type II is the most common type and represents a detachment of the superior labrum and biceps from the glenoid rim. Type III represents a bucket-handle tear of the labrum with an intact biceps tendon insertion to the bone. Finally, type IV lesions, the least common type represents an intra-substance tear of the biceps tendon with a bucket-handle tear of the superior aspect of the labrum.
Clinically Relevant Anatomy
The shoulder complex is one of the most sophisticated areas of the body. The shoulder is made up of five joints; the Acromioclavicular Joint, the Sternoclavicular Joint, the Glenohumeral Joint, Scapulothoracic Joint and Suprahumeral Joint and four linked bone groups; the clavicula, sternum, Scapula and the humerus which are related and work together.
The major joint is the Glenohumeral Joint, which is also called the ‘ball in a socket’ joint because of the humeral head (ball) that articulates with the glenoid cavity (glenoid fossa of scapula or socket).But the humeral head is larger than the fossa and so the socket covers only a quarter of the humeral head.
A circumflexial rim of fibrocartilaginous tissue called labrum glenoidalis firmly attaches to the glenoid fossa thereby increasing the articular surface area and the stabilisation of the glenohumeral joint.
The long arm of the biceps inserts directly into the superior labrum, which also provides stabilisation to the superior part of the joint.In addition, the rotator_Cuff muscles are essential to ensure dynamic shoulder stability as they prevent excessive translations of the humeral head at the level of the glenoid fossa.[8]
Important variations in the normal anatomy of the labrum have been identified. Three distinct variations occur in over 10% of patients:
An isolated sublabral foramen,
A sublabral foramen with a cord-like middle glenohumeral ligament
A cordlike middle glenohumeral ligament without tissue at the anterosuperior labrum. The identification of these normal variants can help to prevent the misdiagnosis of labral lesions.
Epidemiology/Aetiology
The age of the patient has an impact on the superior labrum. From the average age of 35, the superior labrum is less firmly attached to the glenoid than in people under the age of 30. In the age category 30 to 50, there are more chances of tears/defects in the superior and anterior-superior regions of the labrum (noted in cadavers). In the age category 60 years or older, circumferential lesions have been identified. Thus, we can conclude that there is an age-related effect in which the older the patient is, the more likely he will incur a LAP lesion, due to age-related changes.
In one study, half of the cases that had a SLAP lesion were 40 years old patients who showed signs and symptoms of instability after a history of acute trauma, repetitive injury, fall on an outstretched arm, or an injury from heavy lifting. Most of them had a type II SLAP lesion. They also noticed that the type II SLAP lesions in patients under 40 were associated with a bankart_lesion , other than a type II SLAP lesion in patients under 40 years old, whose SLAP lesion were associated with a tear of the supraspinatus tendon and osteoarthritis of the humeral head.
There are a lot of different mechanisms of injury that can result in a SLAP lesion. The following causes have been found:
repetitive throwing, hyperextension, a fall on an outstretched arm, heavy lifting, direct trauma. The two most common mechanisms are falling on an outstretched arm in which there is a superior compression, and a traction injury in the inferior direction.
Falling on an outstretched arm is an acute traumatic superior compression force to the shoulder. In this situation the shoulder is abducted and slightly forward-flexed at the time of the impact
A subsequent study found that the most common mechanism of injury was a …
fall or direct blow to the shoulder, occurring in 31% of patients. A significant number of patients with superior glenoid lesions and concomitant impingement or rotator cuff disease in the absence of trauma has also been identified. Indeed, Snyder et al found partial-thickness or full-thickness rotator cuff disease in 55 (40%) of 140 patients with SLAP lesions. Superior migration of the humeral head can result from a rotator cuff that is not effectively performing its role as a humeral head depressor.
The superior labrum and biceps anchor could theoretically be gradually lifted off the glenoid as a result of chronic repetitive superior translation of the humeral head on the glenoid rim. Other authors supported the theory of an inferior traction mechanism on the basis of a sudden, traumatic, inferior pull on the arm or repetitive microtrauma from overhead sports activity with associated instability
Throwers can have repetitive microtraumata. At the moment of the impact the glenohumeral contact point is shifted posterosuperiorly and increased shear forces are placed on the posterior-superior labrum, which results in a peel-back effect and eventually in a SLAP lesion.
Clinical Presentation
The most common complaint in patients that present with SLAP lesions is pain. Pain is typically intermittent and often associated with overhead movements.Isolated SLAP lesions are uncommon.The majority of patients with SLAP lesions will also complain of:
sensations of painful clicking and/or popping with shoulder movement
loss of glenohumeral internal rotation range of motion
pain with overhead motions
loss of rotator cuff muscular strength and endurance
loss of scapular stabiliser muscle strength and enduranc
inability to lie on the affected shoulder
Athletes performing overhead movements, especially pitchers, may develop “dead arm” syndrome in which they have a painful shoulder with throwing and can no longer throw with pre-injury velocity.[13]They may also report a loss of velocity and accuracy along with discomfort in the shoulder
Differential Diagnosis
The glenoid labrum is often involved in shoulder pathology. Sometimes morphological varieties can be confused with pathological aspects and therefore diagnosis should be established following careful analysis of the case history and a physical examination.[16]There are two regions where anatomic variants can appear: the superior region, where it’s mostly related to age, and the anterosuperior region, where sometimes there is no labrum (12%) or a cord like ligament that is in continuity with the biceps footplate (13,5%).
SLAP tear itself accounts for 80–90% of labral pathology in stable shoulder but it’s only found in 6% on arthroscopy. SLAP lesions are often seen in combination with other shoulder problems and this makes it difficult to diagnose.[17]SLAP lesion is mostly combined with a lesion of the proximal head of the biceps because it attaches on the superior part of the labrum glenoidalis. It is associated with pain and instability and an inability of the patient to perform overhead movements.
According to William F.B., SLAP lesions had an association of 43% with the medial sheath lesion. the author postulates that forces that affect the biceps anchor may also damage the pulley system of the bicipital sheath and, as such, this anatomic structure should be evaluated, especially when SLAP lesions are present.
Beside biceps tears, other problems, such as bursitis and rotator cuff tears, are often identified. In combination with SLAP lesions,
According to Morgan CD et al., Rotator cuff tears were present in 31% of patients whit SLAP lesion and were found to be lesion-location specific.
Also suprascapular neuropathy secondary to cyst compression in the spinoglenoid notch may occur in association with SLAP tears
Diagnostic Procedures
SLAP lesions are difficult to diagnose as they are very similar to those of instability and rotator cuff disorders. At first the clinician can test the tenderness to palpation at the rotator interval which can be helpful in the diagnostic procedure. The rotator interval is an anatomic space between the Supraspinatus tendon, the Subscapularis tendon and the processus coracoideus. This rotator interval has a triangular shape in which the supraspinatus is superiorly located, the subscapularis inferiorly and the processus coracoideus medially. It contains the coracohumeral and the superior glenohumeral ligament, the biceps tendon and the anterior joint capsule. If you know where these structures are situated, you can try to palpate the rotator interval.
This can be followed by these tests that are positive when there is a presence of a SLAP lesion: positive anterior drawer (53%), positive apprehension at 90° of abduction and maximal external rotation (86%), and positive relocation test (86%).
In addition, several special tests can be used to help identify the presence of a SLAP lesion including the Clunk test, the crank test, O’ Briens, Anterior Slide test, Biceps Load I and II test, and the Active Compression test.
Another very important diagnostic element is the use of clear radiological and arthroscopic images of the labrum, which can help clinicians to distinguish the pathology from normal variation and make the correct diagnosis.
MRI is the most common imaging tool used to diagnose labral lesions, although it may not show a SLAP lesion. Therefore an MR arthrogram, where a contrast material gets injected into the shoulder, is also used. This is able to detect a SLAP tear better than a normal MRI scan.[22]
Thus, MRA is more useful than conventional MRI and CT arthrography, and is a helpful technique in the diagnosis of SLAP tears. However, there is a great chance of false positive results due to a superior labral recess or sulcus, which is a normal variant, but can make the diagnosis more difficult
Examination
Clinical examination to detect SLAP lesions is an extremely challenging procedure because the condition is frequently associated with other shoulder pathologies in patients presenting this type of condition.
As with most shoulder conditions, the history including the exact mechanism of injury should be documented.[10][12][14] It is important to keep in mind that while labral pathologies are frequently caused by overuse, the patient may also describe a single traumatic event.The physical examination is also very important in determining the correct diagnosis, however physical examination should not be used in isolation because the literature does not confirm that special tests can accurately identify SLAP lesions.
There are numerous physical examination procedures described to detect the SLAP lesion:
Biceps load test II O’Brien test Anterior apprehension test Speeds Testt Yergason’s test Compression rotation test Dynamic labral shear test A combination of 2 sensitive tests and 1 specific test is more efficient to diagnose a SLAP lesion [reference needed].
The therapist can choose the 2 sensitive tests out of the following 3:
Compression rotation test
O’Brien test
Anterior apprehension test
For the specific test, the therapist may choose out of the 3 following:
Speed’s test
Yergason’s test
Biceps load test II
If one of the three tests is positive, this will result in a sensitivity of about 75%. But if all three tests are positive this will result in a specificity of about 90%.
When we consider some tests individually, one can consider the Speed’s test and O’Brien’s test helpful in the diagnosis of anterior lesions and the Jobes Relocation Test is often positive in a posterior lesion According to Meserve et al, the O’Brien test is the most sensitive test (47%-78%) and the Speed’s test the most specific (67%-99%).There are studies who combined few of the tests but the data differ too much therefore it’s difficult to make a general conclusion.
There is a lot of discussion about which test is most accurate, but most experts consider that arthroscopy is the best way to diagnose SLAP lesion
