Biceps Tendinitis

The structure of the biceps tendon is revealed in its name with “biceps” meaning two heads. The long head of the biceps originates at the top portion of the shoulder socket called the superior labrum of the glenoid. On the other hand, the short head originates from the important coracoid process. The long head of the biceps which actually sits within the shoulder joint travels between the front rotator cuff muscle (subscapularis) and the superior rotator cuff tendon (supraspinatus). This portion of the shoulder joint is called the rotator interval. Because the biceps runs so close to the rotator cuff, oftentimes rotator cuff inflammation can also inflame the biceps tendon as a secondary pain generator. As the biceps continues down the arm, it is covered by its own tendon sheath called the bicipital sheath. The long head then enters the bicipital groove between the lesser and greater tuberosities and is stabilized by the overlying transverse humeral ligament. At this point near the midportion of the arm, both the long head and short head muscle bellies combine to form the main biceps muscle and the distal tendon wraps around and attaches on the ulnar side of the radial tuberosity in the proximal forearm.

The biceps has three important functions:

1. Supination: Supination is the primary function of the biceps and is defined as turning the palm from facing down to facing up. Supination is important in twisting activities such as turning a screwdriver, opening a door, or opening a jar.
2. Flexion: While we tend to think of the biceps as more of an elbow flexor, actually the brachialis muscle which sits deeper to the biceps provides 60% of elbow flexion strength and is more important in flexion than the biceps. The biceps is still an important elbow flexor but not as important as the brachialis.
3. Stability: Because the long head of the biceps originates within the shoulder joint, the long head may help prevent excessive anterior translation of the humeral head. Though the importance of the long head of the biceps in shoulder stability has been questioned over time, it may still provide a small amount of this anterior stability.

Inflammation within the biceps tendon has multiple potential causes:

1. Overuse: Repetitive overhead activity can strain the biceps tendon and is seen in the athletic population that engages in repetitive overhead throwing, lifting, or swimming. This is also seen in the manual labor population with heavy or repetitive activities above shoulder height.
2. Shoulder instability: Additionally, the biceps can be inflamed if the shoulder is unstable with the long head of the biceps being pinched due to an unstable humeral head. Instability itself can be due to problems with the shoulder labrum or the rotator cuff.
3. Intrinsic degeneration: Age-related tendon degeneration can occur through no external causes but just due to gradual wear and tear of the tendon over time.
4. Scapular dyskinesia: An under-recognized cause of biceps tendinitis is poor posture or scapular mechanics where due to poor positioning of the scapula, the biceps tendon in the front of the shoulder actually gets pinched.
5. Trauma: The biceps can also be acutely strained or even ruptured after a fall and patients often complain of a sudden pain in the front of the shoulder, muscle cramping, and deformity. However, it is important to note that these ruptures are always isolated to the long head of the biceps tendon which is not the main strength generator of the biceps.

1. Biceps tendinitis commonly presents as deep anterior shoulder pain which radiates down the front of the arm into the biceps muscle belly.
2. Patients often have pain with lifting, reaching overhead, or rotating the arm that further tensions the biceps muscle.
3. If there is an associated superior labrum tear, because the long head of the biceps originates from that same area, there can be associated clicking and catching.
4. As discussed before, because the biceps runs in close proximity to the rotator cuff as it passes through the rotator cuff interval, there can be some rotator cuff associated inflammation and pain with nighttime pain or weakness with lifting overhead.

Biceps tendinitis is first diagnosed with a thorough history and physical exam. On the history, the common symptoms as detailed above will be present and confirmed on the exam with biceps-specific maneuvers. Patients often have tenderness with direct palpation in the bicipital groove and the specific tests of a Speed’s test and a Yergason’s test, which tensions the biceps during resisted forward flexion and resisted forearm supination respectively will also irritate the biceps if it is inflamed. It is essential to distinguish isolated biceps tendinitis from secondary tendinitis associated with labral or cuff pathology

Imaging studies are usually not needed to diagnose pure biceps tendinitis but are often obtained if the biceps tendon is inflamed in conjunction with other shoulder conditions

1. X-rays are useful to rule out bony abnormalities or glenohumeral arthritis.
2. Ultrasound is useful for dynamic visualization of the tendon because as the arm is brought through rotational motion, if there is tendon instability, the tendon can be seen subluxing in and out of the bicipital groove.
3. An MRI is often obtained when other shoulder pathology is suspected, but can also be scrutinized to specifically evaluate the biceps for partial vs complete tearing of the tendon versus inflammation within the tendon sheath called tendinopathy.