Biceps Tendonitis

The biceps muscle has two tendons at the shoulder. The short head attaches to the coracoid process and is rarely a source of trouble. The long head is the one that matters clinically: it originates inside the shoulder joint at the top of the socket, runs across the top of the ball, and then turns sharply downward into a bony groove at the front of the upper arm bone. It is held in that groove by a sling of tissue formed in part by the rotator cuff tendons.

Biceps tendonitis is inflammation and degeneration of this long head tendon. Because the tendon makes a sharp turn, sits in a confined groove, and passes through the joint itself, it is subject to compression, friction, and traction in a way few tendons are. Over time the inflammation of a young athlete’s tendon gives way to the thickening, fraying, and degeneration seen in older patients, a state more accurately called tendinopathy.

The tendon rarely fails in isolation. Its stability depends on the surrounding sling, so a rotator cuff tear involving the subscapularis frequently allows the tendon to subluxate or dislocate out of its groove, and biceps pain is often the first symptom of a cuff problem rather than a separate condition.

• Repetitive overhead activity: Throwing, swimming, racquet sports, and overhead trades load the tendon through its full excursion thousands of times.
• Repetitive lifting and pulling: Curls, pull-ups, and occupational lifting with the palm up load the tendon directly.
• Rotator cuff disease: A torn or degenerative cuff, particularly the subscapularis, destabilizes the tendon within its groove and is among the most common causes in patients past middle age.
• Impingement: Compression beneath the acromion affects the biceps tendon as well as the cuff, which is why the two so often occur together.
• Shoulder instability and labral tears: Because the tendon originates on the labrum, instability and SLAP tears place abnormal traction on its origin.
• Age-related degeneration: The tendon thins and frays with time, sometimes progressing to spontaneous rupture.
• Direct trauma: A fall onto the shoulder or a sudden eccentric load can injure the tendon acutely.

• Pain at the front of the shoulder: Localized to the groove at the front of the upper arm bone, often radiating down the front of the arm toward the elbow.
• Pain with lifting and reaching forward: Discomfort carrying a bag, lifting a child, or reaching into the back seat.
• Pain with palm-up lifting: Curls and similar movements characteristically reproduce the symptoms.
• Night pain: Difficulty sleeping on the affected side, which biceps tendonitis shares with impingement and cuff disease.
• Clicking or snapping: A sensation of the tendon catching or snapping with rotation, which suggests the tendon is unstable in its groove and raises concern for a subscapularis tear.
• A “Popeye” deformity: A bulge in the lower arm after a sudden pop, which indicates the tendon has ruptured. Pain often improves considerably once this happens.

Diagnosis begins with a thorough evaluation by Dr. Rynecki Baker. The history covers sport, occupation, lifting habits, and whether there was a sudden event or a gradual build. On examination she palpates the groove directly and follows its position as the arm rotates, performs provocative tests that load the tendon with the palm up, and examines the rotator cuff carefully, particularly the subscapularis, because tendon instability rarely occurs without cuff involvement. Distinguishing biceps pain from impingement, rotator cuff tearing, AC joint arthritis, and a labral tear is the central task, and these conditions frequently coexist.

X-rays are used to assess the bony anatomy of the groove, the shape of the acromion, and associated arthritis. MRI demonstrates thickening, fluid around the tendon, partial tearing, and whether the tendon remains seated in its groove. It also evaluates the rotator cuff and labrum. Ultrasound allows dynamic assessment of the tendon as the arm rotates, which can reveal instability that a static image misses. An ultrasound-guided injection of local anesthetic around the tendon can confirm it as the source of pain when the clinical picture is mixed.

The long head of the biceps is the most commonly under-recognized source of shoulder pain. Patients are treated for impingement for months, undergo a decompression, and remain symptomatic because the tendon was never addressed. Others are told the tendon is the problem when the actual driver is a subscapularis tear that has allowed it to become unstable, and treating the tendon alone leaves the underlying cause in place.

Dr. Rynecki Baker’s training at NYU Langone Health and Hospital for Special Surgery, her dedicated focus on shoulder surgery and sports medicine, and her published research in shoulder surgery mean patients are evaluated by a specialist who examines the biceps tendon deliberately rather than by exclusion, and who looks for the reason the tendon became symptomatic. She understands what persistent front-of-shoulder pain does to training and to sleep.