Abstract
Rotator cuff tears are a common cause of shoulder pain and dysfunction. A rotator cuff tear frequently occurs after seemingly minor trauma to the musculotendinous unit of the shoulder. However, in most cases, the pathologic process responsible for the tear has been a long time in the making and is the result of ongoing tendinitis. The rotator cuff is made up of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and the associated tendons. The function of the rotator cuff is to rotate the arm and help provide shoulder joint stability along with the other muscles, tendons, and ligaments of the shoulder.
The supraspinatus and infraspinatus muscle tendons are particularly susceptible to the development of tendinitis, for several reasons. First, the joint is subjected to many different repetitive motions. Second, the space in which the musculotendinous unit functions is restricted by the coracoacromial arch, thus making impingement likely with extreme joint movements. Third, the blood supply to the musculotendinous unit is poor, and this makes healing of microtrauma difficult. All these factors can contribute to tendinitis of one or more tendons of the shoulder joint. Calcium deposition around the tendon may occur if the inflammation continues and complicates subsequent treatment. Bursitis often accompanies rotator cuff tears and may require specific treatment.
In addition to pain, patients suffering from rotator cuff tear often experience a gradual reduction in functional ability because of decreasing shoulder range of motion that makes simple everyday tasks such as combing one’s hair, fastening a brassiere, or reaching overhead quite difficult. With continued disuse, muscle wasting may occur, and a frozen shoulder may develop.
Keywords
shoulder pain, supraspinatus muscle, infraspinatus muscle, teres minor muscle, shoulder injection, ultrasound guided injection, acromioclavicular impingement, drop arm test
ICD-10 CODES
S43.429A Traumatic
M75.10 Nontraumatic
The Clinical Syndrome
Rotator cuff tears are a common cause of shoulder pain and dysfunction. A rotator cuff tear frequently occurs after seemingly minor trauma to the musculotendinous unit of the shoulder. However, in most cases, the pathologic process responsible for the tear has been a long time in the making and is the result of ongoing tendinitis. The rotator cuff is made up of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and the associated tendons ( Fig. 33.1 ). The function of the rotator cuff is to rotate the arm and help provide shoulder joint stability along with the other muscles, tendons, and ligaments of the shoulder.
The supraspinatus and infraspinatus muscle tendons are particularly susceptible to the development of tendinitis, for several reasons. First, the joint is subjected to many different repetitive motions. Second, the space in which the musculotendinous unit functions is restricted by the coracoacromial arch, thus making impingement likely with extreme joint movements. Third, the blood supply to the musculotendinous unit is poor, and this makes healing of microtrauma difficult. All these factors can contribute to tendinitis of one or more tendons of the shoulder joint. Calcium deposition around the tendon may occur if the inflammation continues and complicates subsequent treatment. Bursitis often accompanies rotator cuff tears and may require specific treatment.
In addition to pain, patients suffering from rotator cuff tear often experience a gradual reduction in functional ability because of decreasing shoulder range of motion that makes simple everyday tasks such as combing one’s hair, fastening a brassiere, or reaching overhead quite difficult. With continued disuse, muscle wasting may occur, and a frozen shoulder may develop.
Signs and Symptoms
Patients presenting with rotator cuff tear frequently complain that they cannot raise the affected arm above the level of the shoulder without using the other arm to lift it ( Fig. 33.2 ). On physical examination, weakness on external rotation is noted if the infraspinatus is involved, and weakness on abduction above the level of the shoulder is evident if the supraspinatus is involved. Tenderness to palpation in the subacromial region is often present. Patients with partial rotator cuff tears lose the ability to reach overhead smoothly. Patients with complete tears exhibit anterior migration of the humeral head, as well as a complete inability to reach above the level of the shoulder. A positive drop arm test—the inability to hold the arm abducted at the level of the shoulder after the supported arm is released—is often seen with complete tears of the rotator cuff ( Fig. 33.3 ). The result of Moseley’s test for rotator cuff tear is also positive; this test is performed by having the patient actively abduct the arm to 80 degrees and then adding gentle resistance, which forces the arm to drop if complete rotator cuff tear is present. Passive range of motion of the shoulder is normal, but active range of motion is limited.
