Proximal Biceps Tendon Rupture

The long head of the biceps muscle attaches to bone via tendons—one at the shoulder and one at the elbow. The biceps muscle is important for bending the elbow and supinating the forearm (rotating the hand to the palm up position). At the shoulder, the biceps tendon runs in a groove on the bone of the humerus (arm), makes an almost 90-degree turn, enters the shoulder joint between subscapularis (front) and supraspinatus (top) rotator cuff tendons, then attaches to the top of the glenoid (socket of the shoulder joint). The biceps is held in the bony groove of the humerus by the transverse humeral ligament and portions of the coracohumeral and superior glenohumeral ligaments. After an injury to these restraining ligaments, the tendon may begin to move in and out of this groove with shoulder motion, resulting in a condition known as biceps instability. The abnormal motion of the biceps tendon damages and tears the tendon as it crosses back and forth over the bony edge of the groove. Injury to these restraining ligaments is often associated with a partial or complete tear of the subscapularis or supraspinatus rotator cuff tendon. Over time, or with significant injury mechanism, the biceps tendon can rupture completely.