Rotator cuff injury of the shoulder joint

Rotator cuff injuries are classified as strains, tendonitis, and partial or complete tears.

The rotator cuff, composed of the supraspinatus, infraspinatus, teres minor, and subscapularis muscles, helps stabilize the humerus in the glenoid cavity of the scapula during many athletic upward arm movements (e.g., throwing, swimming, weight lifting, and tennis). Injuries include strains, tendinitis, partial tears, and complete tears.

Tendinitis usually results from compression of the supraspinatus tendon between the humeral head and the coracoacromial arch (acromion, acromioclavicular joint, coracoid process, and coracoacromial ligament). This tendon is considered particularly vulnerable because it has a poorly vascularized area near its insertion on the greater tuberosity. The resulting inflammatory response and swelling further narrow the subacromial space, accelerating the process. If unchecked, tendinitis may progress to fibrosis, or a complete or partial rupture may occur. Degenerative rotator cuff disease is common in people >40 years of age who do not play sports. Subacromial (subdeltoid) bursitis is the most common manifestation of rotator cuff injury.

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Symptoms and Diagnosis of Rotator Cuff Injury

Symptoms of bursitis include shoulder pain, especially with upper body movement, and muscle weakness. Pain is usually worse between 80-120° (especially severe with movement) with shoulder abduction or flexion and is usually minimal or absent between <80° and >120°. Signs may vary in severity. Incomplete tendon rupture and inflammation produce similar symptoms.

The diagnosis is based on the anamnesis and clinical examination. The area of damage to the rotator cuff cannot be directly palpated, but can be indirectly assessed by special techniques testing individual muscles. Severe pain or weakness is considered a positive result.

The condition of the supraspinatus muscle is assessed by the patient's resistance to pressure applied to the arms from above, the patient holds the arms in forward flexion, with the thumbs pointing downwards (the "empty can" test).

The infraspinatus and teres minor muscles are assessed by having the patient resist pressure with external rotation, arms at sides with elbows bent at right angles. This position isolates rotator cuff function from other muscles such as the deltoid. Weakness during this test suggests significant rotator cuff dysfunction (eg, complete tear).

The subscapularis muscle is assessed by the patient's resistance to pressure with internal rotation, or by placing the back of the patient's hand on his back and asking him to try to raise his arm.

Other tests include the Epley scratch test, Neer test, and Hawkins test. The Epley scratch test tests shoulder range of motion, abduction, and external rotation by having the patient attempt to touch the opposite scapula with their fingertips while holding their hand overhead behind their neck; adduction and internal rotation by having the patient attempt to touch the opposite scapula from below behind their back and diagonally with the back of their hand. The Neer test looks for rotator cuff tendon dysfunction under the coracoacromial arch, and is performed with the patient's arms in forced flexion (overhead) with full arm pronation. The Hawkins test also looks for supraspinatus tendon compression by having the patient's arm raised to a 90-degree angle while the shoulder is strongly rotated medially.

The acromioclavicular and sternoclavicular joints, cervical vertebrae, biceps tendon, and scapula should be palpated to identify areas of tenderness or defect and to exclude pathological conditions associated with damage to these areas.

The neck should always be examined when examining the shoulder because pain from the cervical vertebrae can radiate to the shoulder (especially with C5 radiculopathy).

If a rotator cuff injury is suspected, MRI, arthroscopy, or both should be performed.

Treatment of rotator cuff injury

In most cases, rest and strengthening exercises are sufficient. Surgery may be necessary if the injury is severe (e.g., complete rupture), especially in younger patients.