Corticosteroid injection procedures are used to diagnose and treat rotator cuff tendonitis or subacromial bursitis. These conditions are often due to nonspecific irritation of the subacromial bursa, lesions of the rotator cuff, calcific tendonitis, or rheumatoid arthritis.
After informed consent is obtained, the patient is placed in a sitting position with the arm in the lap. The lateral aspect of the shoulder is palpated for the point of maximal tenderness, usually 1 to 2 cm inferiorly and 1 to 2 cm anteriorly to the angle of the acromion. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1½-in. (4-cm), 21-gauge needle is inserted below the acromion at the point of maximal tenderness. The needle is gently manipulated under the acromion. Aspiration is attempted until the needle has entered the synovial space. The subacromial bursa is about 1 to 2 cm below the skin between the tip of the acromion process and the head of the humerus. If there is an effusion of the bursa, the aspiration should be completed. After negative aspiration, or if the aspirated fluid is noninflammatory (clear and viscous), a 5-mL mixture of 20 mg of triamcinolone acetonide (or equivalent) and local anesthetic is injected. Half of the mixture should be injected under the acromion in the bursa. The needle should be slightly withdrawn and redirected toward the anterior part of the rotator cuff, and the remainder of the mixture infiltrated (see Fig. 67-37B).
FIGURE 67-37. Shoulder joint injections. A: Approach for shoulder joint aspiration and injection. Acromioclavicular joint injection. B: Approach for shoulder joint aspiration and injection. Rotator cuff tendon/subacromial bursa injection.
Shoulder x-rays may show the locations of calcific deposits. If noted, a 1½-in. (4-cm), 16- to 18-gauge needle is directed to this area and aspiration attempted. Three mL of the mixture is injected at this location. The needle is withdrawn slightly and redirected toward the anterior part of the rotator cuff, and the remainder of the mixture infiltrated. This type of injection is usually uncomfortable, and premedication with codeine or oxycodone should be considered.
Corticosteroids should not be injected if there is any suspicion that the bursa is infected. If the fluid appears infected, it should be sent for culture and sensitivity and the patient treated appropriately for the infection.