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The long head of the biceps tendon (LHBT) originates from the superior labrum and the glenoid of the scapula. It lies between the supraspinatus and subscapularis tendons, namely, the rotator interval. Superior labrum anterior to posterior (SLAP) lesion is a tear of the superior labrum near the attachment of the LHBT.1 It is frequently encountered in overhead throwing activities when overloading of the LHBT occurs during extreme range of shoulder external rotation at late-cocking phase, or rapid deceleration of the arm at follow-through phase.2,3 The clinical diagnosis can be quite challenging because of its nonspecific symptoms and its frequent association with other shoulder pathology such as rotator cuff tears.1,4 Ultrasound (US) had not been considered feasible for evaluation of LHBT insertion at the superior labrum, partly owing to blocking of surrounding bony structures and inadequate penetration of ultrasound beam. Arthroscopy, arthrography, or magnetic resonance imaging is usually required for a definite diagnosis.2,5
We propose a novel method for dynamic evaluation of the LHBT insertion at the superior labrum. A low-frequency (5–8 MHz) curvilinear probe is required for better penetration and extended view. The patient places the ipsilateral hand on the waist, with the elbow pointing laterally. In this position, the LHBT is slightly rotated anteriorly and shifted from beneath the acromion. The probe is put in the oblique coronal plane at the window between the coracoid process and acromioclavicular joint, parallel to the orientation of the LHBT (Fig. 1A, left lower insert). The LHBT appears as a fibrillar hyperechoic band, coursing around the superior humeral head, and inserts on the triangular hyperechoic superior labrum (Fig. 1A). Note that the intra-articular portion of LHBT becomes hypoechoic owing to anisotropy, as the tendon goes deeper gradually. Video 1 demonstrates tracing of the LHBT from the bicipital groove to its proximal insertion.
Dynamic examination is performed by supinating and pronating the forearm while keeping the upper arm fixed. The LHBT is stretched when the forearm is actively supinated, causing traction of the tendon at the superior labrum. The lateral edge of the superior labrum becomes better visualized as well as the intra-articular portion of LHBT (Fig. 1B). The integrity of the anterior superior glenohumeral joint and peritendinous fluid can be assessed in this maneuver. The dynamic imaging is also presented in the attached video (Video 2).
The demonstration of labral insertion of LHBT allows for evaluation of a possible SLAP lesion. A dynamic stress test, by applying an inferior distraction force to the humerus, can also be done (Fig. 2 and Video 3). Investigation of a proximal LHBT lesion must be cautious owing to the anisotropy effect. It should be noted that part of the superior labrum, other than the insertion of LHBT, is difficult to evaluate by US, and arthrography or magnetic resonance imaging remains the diagnostic choices in case of SLAP lesion. Yet, with the advantages of excellent diagnostic power for accompanying rotator cuff lesions, noninvasiveness, accessibility, and relatively low-cost US can serve as a useful tool for screening for suspected SLAP and accompanying lesions and for follow-up of treatment.
1. Maffet MW, Gartsman GM, Moseley B: Superior labrum-biceps tendon complex lesions of the shoulder. Am J Sports Med
2. Knesek M, Skendzel JG, Dines JS, et al.: Diagnosis and management of superior labral anterior posterior tears in throwing athletes. Am J Sports Med
3. Barber FA, Field LD, Ryu RK: Biceps tendon and superior labrum injuries: decision making. Instr Course Lect
4. Grauer JD, Paulos LE, Smutz WP: Biceps tendon and superior labral injuries. Arthroscopy
5. Aydin N, Sirin E, Arya A: Superior labrum anterior to posterior lesions of the shoulder: diagnosis and arthroscopic management. World J Orthop