Subcoracoid Bursa Injection

Indications and Clinical Considerations

Bursae are formed from synovial sacs whose purpose is to allow easy sliding of muscles and tendons across one another at areas of repeated movement. These synovial sacs are lined with a synovial membrane invested with a network of blood vessels that secrete synovial fluid. Inflammation of the bursa results in an increase in the production of synovial fluid with swelling of the bursal sac. With overuse or misuse, these bursae may become inflamed, enlarged, and, on rare occasions, infected. Although there is significant intrapatient variability as to the number, size, and location of bursae, anatomists have identified a number of clinically relevant bursae, including the subcoracoid bursa. The subcoracoid bursa lies between the joint capsule and the coracoid process ( Fig. 49.1 ). It may exist as a single bursal sac or, in some patients, as a multisegmented series of sacs that may be loculated.

The subcoracoid bursa is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries frequently take the form of direct trauma to the shoulder that occurs when playing sports or from falling on the shoulder. The repeated strain associated with repetitive motion may result in inflammation of the subcoracoid bursa. If the inflammation of the subcoracoid bursa becomes chronic, calcification of the bursa may occur.

The patient with subcoracoid bursitis frequently notes pain with forward movement and adduction of the shoulder. The pain is localized to the area over the coracoid process, with referred pain noted at the medial shoulder. Often, the patient is unable to sleep on the affected shoulder, and he or she may report a sharp, “catching” sensation when abducting the shoulder, especially on first awakening. Physical examination may reveal point tenderness over the coracoid process ( Fig. 49.2 ). Passive elevation and active internal rotation of the affected shoulder will reproduce the pain of subcoracoid bursitis, as do resisted adduction and internal rotation ( Fig. 49.3 ). The abduction release test is also highly diagnostic for subcoracoid bursitis. For this test, the patient is asked to adduct the affected arm against the examiner’s resistance ( Fig. 49.4 ). The examiner, without warning, suddenly releases the resistance, which should result in a marked increase in pain symptoms ( Fig. 49.5 ).

Plain radiographs of the shoulder may reveal calcification of the bursa and associated structures consistent with chronic inflammation. Magnetic resonance imaging (MRI) and/or ultrasound imaging will help identify the presence of subcoracoid bursitis and coexistent shoulder disease ( Fig. 49.6 ). Ultrasound imaging may also be helpful in identifying the inciting factors responsible for subcoracoid bursitis. MRI and/or ultrasound imaging is also indicated if disruption of the ligaments is suspected. The injection technique described later serves as both a diagnostic and a therapeutic maneuver.

Clinically Relevant Anatomy

The coracoid process of the scapula projects upward and forward above the glenoid fossa (see Figs. 49.1 and 49.7 ). The coracoid process provides attachment for the coracoclavicular ligament as well as the short head of the biceps. The long head of the biceps has its origin just inferior to the coracoid process in the supraglenoid tubercle of the scapula. The long head exits the shoulder joint via the bicipital groove, where it is susceptible to tendinitis. The long head is joined by the short head in the middle portion of the upper arm. The insertion of the biceps muscle is into the posterior portion of the radial tuberosity.

The subcoracoid bursa lies between the joint capsule and the coracoid process. It is susceptible to irritation by pressure from the coracoid process against the head of the humerus during extreme arm movement or when previous damage to the musculotendinous unit of the shoulder allows abnormal movement of the head of the humerus in the glenoid fossa.