The musculotendinous units of the shoulder are subjected to an amazing variation of stresses as they perform their function of allowing a full range of motion of the shoulder while at the same time providing shoulder stability. The relatively poor blood supply limits the ability of these muscles and tendons to heal when traumatized. Over time, muscle tears and tendinopathy develop, further weakening the musculotendinous units and making them susceptible to additional damage. The potential for impingement as the bicipital musculotendinous unit passes beneath the coracoacromial arch can further exacerbate the problem and further inflame and damage the structures (Fig. 46.1). Over time, if the trauma and subsequent inflammation continues, calcium deposition around the tendon with resultant calcific tendonitis may occur, making subsequent treatment more difficult. Tendonitis of the musculotendinous units of the shoulder frequently coexists with bursitis of the associated bursae of the shoulder joint, creating additional pain and functional disability.

The long and short tendons of the biceps are susceptible to the development of tendonitis following even seemingly minor trauma (Fig. 46.2). The onset of bicipital tendonitis is usually acute, occurring after overuse or misuse of the shoulder joint. Inciting factors may include activities such as trying to start a recalcitrant lawn mower, practicing an overhead tennis serve, or overaggressive follow-through when driving golf balls. The pain of bicipital tendonitis is constant, severe, and localized in the anterior shoulder over the bicipital groove. A “catching” sensation also may accompany the pain. Significant sleep disturbance is often reported. The patient may attempt to splint the inflamed tendons by internal rotation of the humerus, which moves the biceps tendon from beneath the coracoacromial arch. Patients suffering from bicipital tendonitis will exhibit a positive Yergason and/or Speed sign, which is elicited by having the patient flex the elbow and supinate the forearm
against resistance. Maximal pain will be felt in the bicipital groove (Fig. 46.3). If untreated, patients suffering from bicipital tendonitis may experience difficulty in performing any task that requires initial abduction of the upper extremity, making simple everyday tasks such as brushing one’s teeth or eating difficult. Over time, muscle atrophy, calcific tendonitis, and ultimately tendon rupture may result (Fig. 46.4).

Plain radiographs are indicated in all patients who present with shoulder pain. Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Ultrasound imaging or magnetic resonance imaging of the shoulder is indicated if a bicipital tendonitis is suspected as well as to aid in the evaluation of the affected area and may also help delineate the presence of tendinopathy, calcific tendonitis, bursitis, tendon rupture, or other shoulder pathology (Fig. 46.5).

Along with the conjoined tendons of the rotator cuff, the bicipital muscle serves to stabilize the shoulder joint. The biceps muscle, which is named for its two heads, functions to supinate the forearm and flex the elbow joint (Fig. 46.6). The long head finds its origin in the supraglenoid tubercle of the scapula, and the short head finds its origin from the tip of the coracoid process of the scapula. The long head exits the shoulder joint via the bicipital groove, where it is susceptible to trauma and the development of tendonitis. The long head fuses with the short head in the middle portion of the upper arm forming the belly of the biceps muscle. The insertion of the biceps muscle is into the posterior portion of the radial tuberosity. The biceps muscle is innervated by the musculocutaneous nerve, which arises from the lateral cord of the brachial plexus. The fibers of the musculocutaneous nerve are derived from C5, C6, and C7 nerve roots.