Injection Technique for Rotator Cuff Tear

Indications and Clinical Considerations

Rotator cuff tears frequently occur after seemingly minor trauma to the musculotendinous unit of the shoulder. However, the disease responsible for the tear is usually a long time in the making and is most often the result of ongoing tendinitis. The supraspinatus and infraspinatus muscle tendons are particularly susceptible to the development of tendinitis for several reasons. First, the joint is subjected to a wide range of motions, which are often repetitive. Second, the space in which the musculotendinous unit functions is restricted by the coracoacromial arch, making impingement a likely possibility with extreme movements of the joint. Third, the blood supply to the musculotendinous unit is poor, making healing of microtrauma more difficult. All of these factors can contribute to tendinitis of one or more of the tendons of the shoulder joint. Calcium deposition around the tendon may occur if the inflammation continues, making subsequent treatment more difficult.

Tendinitis of the musculotendinous unit of the shoulder frequently coexists with bursitis of the associated bursae of the shoulder joint, creating additional pain and functional disability. This ongoing pain and functional disability can cause the patient to splint the shoulder group, resulting in abnormal movement of the shoulder, which puts additional stress on the rotator cuff. This can lead to further trauma to the rotator cuff.

Because rotator cuff tears may occur after seemingly minor trauma, the diagnosis often is delayed. The tear may be either partial or complete, further confusing the diagnosis, although careful physical examination and the use of magnetic resonance imaging (MRI) and ultrasonography can help distinguish the two ( Fig. 45.1 ). The patient with a rotator cuff tear frequently complains that he or she cannot lift the arm above the level of the shoulder without using the other arm to lift it.

On physical examination, the patient has weakness on external rotation if the infraspinatus is involved and weakness in abduction above the level of the shoulder if the supraspinatus is involved. Tenderness on palpation in the subacromial region often is present. Patients with partial rotator cuff tears exhibit loss of the ability to smoothly reach overhead. Patients with complete tears exhibit anterior migration of the humeral head and a complete inability to reach above the level of the shoulder. A positive result of the drop arm test, which is the inability to hold the arm abducted at the level of the shoulder after the supported arm is released, is often present with complete tears of the rotator cuff ( Fig. 45.2 ). The Moseley test for rotator cuff tear—which is performed by having the patient actively abduct the arm to 80 degrees and then adding gentle resistance, forcing the arm to drop if complete rotator cuff tear is present—will also yield a positive result. Passive range of motion of the shoulder is normal, but active range of motion is limited.

The pain of a rotator cuff tear is constant and severe and is made worse with abduction and external rotation of the shoulder. Significant sleep disturbance is often reported. The patient may attempt to splint the inflamed subscapularis tendon by limiting medial rotation of the humerus. Bursitis often accompanies rotator cuff tears and may require specific treatment.

In addition to the previously mentioned pain, patients with a rotator cuff tear often experience a gradual decrease in functional ability with decreasing shoulder range of motion, making simple everyday tasks, such as hair combing, fastening a bra, or reaching overhead, quite difficult. With continued disuse, muscle wasting may occur and a frozen shoulder may develop.

Plain radiographs are indicated for all patients with shoulder pain ( Fig. 45.3 ). Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. MRI and/or ultrasound imaging of the shoulder is indicated if a rotator cuff tear is suspected ( Fig. 45.4 ).

Clinically Relevant Anatomy

The rotator cuff is made up of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and associated tendons ( Fig. 45.5 ). The function of the rotator cuff is to rotate the arm and to help provide shoulder joint stability along with the other muscles, tendons, and ligaments of the shoulder. A rotator cuff tear usually involves the supraspinatus or infraspinatus musculotendinous unit, but the other muscles of the rotator cuff can also be involved.