CT and MR Arthrography of the Normal and Pathologic Anterosuperior Labrum and Labral-Bicipital Complex

Interpretation of computed tomographic and magnetic resonance arthrograms of the shoulder is complicated by normal variants of the labrum and glenohumeral ligaments. A superior sublabral recess is located at the 12 o'clock position and represents a normal recess between the superior labrum and the cartilage of the glenoid cavity. A sublabral foramen is located at the 2 o'clock position and represents localized detachment of the labrum from the glenoid rim. Buford complex is characterized by absence of the anterosuperior labrum and cordlike thickening of the middle glenohumeral ligament. Imaging features of damage to the anterior labrum include absence or detachment of the labrum and an irregular frayed appearance. Superior labrum anterior-to-posterior (SLAP) lesions are classified as type I (tear confined to the superior labrum), type II (labrum and biceps tendon detached from the superior glenoid), type III (bucket handle tear of the superior labrum), or type IV (bucket handle tear of the superior labrum with lateral extension into the biceps tendon). Increased distance between the labrum and the glenoid, an irregular appearance of the labral margin, or lateral extension of the separation may suggest a SLAP lesion rather than a normal anatomic variant. However, differentiation between normal variants and pathologic conditions and between various types of SLAP lesions remains difficult.