MRI Musculo-Skeletal Section: Practical MR approach to SLAP injury.

Thursday, July 7, 2016

Practical MR approach to SLAP injury.

We propose an MRI approach for evaluating suspected SLAP lesions based on specific

abnormalities of the biceps-labral complex, presence or absence of extension of the lesion,

and presence or absence of abnormalities of a number of additional structures (ligaments,

adjacent cartilage, and tendons) (Fig. 24).

Fig. 24. —Diagram shows MRI algorithm for superior labral anteroposterior (SLAP) lesions based on specific abnormalities of biceps-labral complex, presence or absence of extension of tear, and presence or absence of abnormalities of additional structures.

-The first step of this approach is related to the evaluation of the characteristics of the

biceps-labral complex. Snyder's classification is used as the basis for this description

because of its simplicity and its widespread use in the literature. The labral tear is further

characterized as nondisplaced or displaced. The criteria used are similar to those used for

the description of torn menisci in the knee. A nondisplaced tear shows on short-TE

sequences as a region of intermediate to high signal intensity that extends to the articular

surface of the labrum. In arthrograms, the gadolinium is expected to extend through this

defect. A displaced tear is one that has a bucket-handle or flap component (Fig. 24). A

displaced tear can also be characterized as a free fragment that has lost its connection

with the parent labrum.

-The second step describes the extension of the superior labral lesion to other areas of the

labrum. To be considered an extended lesion, the labral abnormality must be in anatomic

continuation with the lesion that involves the biceps-labral complex. This step includes the

current types V, VIII, and IX SLAP lesions, as well as the three subdivisions of SLAP II

lesions.

-The third step is related to the description of the associated abnormalities of the

glenohumeral ligaments, joint capsule, articular cartilage, and tendons. Examples are

extension of the lesion through the middle glenohumeral ligament (type VII SLAP lesion);

superior glenohumeral ligament, coracohumeral ligament, rotator interval capsule (type X

SLAP lesion); and inferior glenohumeral ligament (not described in the current SLAP

lesion classifications). Abnormality of the adjacent cartilage such as a chondral flap,

chondral defect, or chondral irregularity should also be considered. Associated

abnormalities of the cuff tendons include undersurface tears of the supraspinatus and

infraspinatus tendons attributed to posterosuperior and anterosuperior internal

impingement and tears of the superior part of the subscapularis tendon and the most

anterior part of the supraspinatus tendon that are associated with rotator interval injuries.

In summary, we suggest a tailored approach to MRI diagnosis of SLAP tears based on

analysis of the biceps-labral complex, the extension of tears, and the associated lesions in

other structures. MRI analysis in multiple planes and close attention to clinical history and

mechanisms of injury are strongly recommended. When appropriate, radiologists should

describe the lesion as indeterminate for sublabral recess versus SLAP lesion and suggest

clinical correlation or MR arthrography for better delineation of the labral abnormality. In

tailored examinations, stress maneuvers such as arm traction [39] or additional planes

such as the one parallel to the biceps tendon [40] may be implemented. Radiologists

should perform a dedicated approach to these lesions with the description of the biceps-

labral complex abnormality; extension of lesions in terms of time zones; and associated

lesions in ligaments, adjacent cartilage, and tendons.