Soft-ball player who complains of several months of right shoulder pain, aggravated by throwing the ball. No history of an acute injury.
No findings of shoulder instability on physical exam.
T1-weighted axial and coronal images with fat-saturation of the shoulder following intra-articular administration of gadolinium. The coronal image demonstrates an irregular collection of contrast extending into the normally dark triangular appearing superior labrum. Axial image demonstrates an irregular collection of contrast between the frayed appearing posterior superior labrum and the posterior glenoid. The Biceps anchor appears normal.
Surgical repair of the torn superior labrum.
The administration of intra-articular gadolinium can be helpful in clearly demonstrating a SLAP lesion on MR imaging. On the coronal images, the superior labrum normally appears as a black triangle extending off of the superior glenoid. Any signal extending into the substance of the triangle is abnormal and represents a SLAP lesion. This can be differentiated from the normal variant sublabral recess, because in a sublabral recess the contrast collection appears smooth and tapering and extends toward the base of the triangle, rather than into the substance of the triangle, as in this SLAP lesion. A sublaral foramen can be differentiated from a SLAP lesion, because a sublabral foramen occurs in the anterior quadrant rather than posterior quadrant and as in the sublabral recess, the contrast collection is smooth and tapering in appearance rather than irregular as demonstrated in this SLAP tear.
When describing a SLAP lesion, it is important to describe the extent of the lesion from front to back, as well as to describe whether there is involvement of the biceps anchor. When using direct MR arthrography, the biceps anchor is usually best evaluated on the axial and sagittal images.
SLAP stands for Superior Labrum from Anterior-to-Posterior, (relative to the biceps tendon anchor).
There are four types of SLAP tears. In type I lesions consist of a frayed and degenerative superior labrum with a normal biceps tendon anchor. Type II lesions demonstrate detachment of the superior labrum and biceps anchor and may also be associated with anterior glenohumeral joint dislocation and anterior instability. SLAP types I and II may be difficult to separate on MRI, depending on the technique used for diagnosis. Type III lesions involve a bucket-handle tear of the superior labrum (a vertical tear through a meniscoid-like superior labrum) without extension into the biceps tendon. The biceps anchor is stable and the remaining labrum is intact. Type IV lesions also involve a bucket-handle tear associated with a meniscoid-type superior labrum, but in this case with extension into the biceps tendon. The biceps anchor and the superior labrum are well attached. A partially torn biceps tendon may displace the superior labral flap into the joint. A complex SLAP lesion may consist of a combination of two or more types, usually type II and type IV.
Possible mechanisms of injury include a fall on the outstretched abducted arm with associated superior joint compression and a proximal subluxation force or a sudden contraction of the biceps tendon, which avulses the superior labrum. Repetitive stress acting through the biceps tendon or instability of the glenohumeral joint may also produce SLAP lesions.
Treatment of SLAP lesions is based on the type of labral lesion present. A type I SLAP lesion is treated with arthroscopic debridement of the degenerative labrum. Treatment of a type II SLAP lesion (which involves detachment of the superior labrum and biceps anchor) addresses the avulsed labrum and reattachment of the detached biceps anchor to the superior glenoid. A suture anchor technique, for example, may be used for a type II SLAP tear.
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