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© 1999 The Journal of Bone and Joint Surgery, Inc. Subacromial Impingement Associated with Deltoid Contracture. A Report of Two Cases* , TOKYO, JAPANInvestigation performed at the Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo
Deltoid contracture can be caused either by repeated intramuscular injections or, in rare cases, by unknown etiologies2,3,6,8,11,12,14,19. The condition occurs in adults as well as in children2,4,8,9,12,13,17,18,21. The typical clinical manifestations are an abduction-extension contracture of the shoulder joint combined with winging of the scapula as compensation for the abduction contracture associated with the formation of a fibrous band within the deltoid muscle2,12,14,18. Adults who have a deltoid contracture commonly have pain that radiates from the neck and the shoulder to the lateral side of the arm4,8,9,12,13,16-18,20,21. We report the cases of two patients who had a deltoid contracture associated with subacromial impingement, and we describe the interrelationship of the two conditions.
CASE 1. A forty-eight-year-old homemaker who had had a nephrectomy for the treatment of hydronephrosis four months earlier was seen because of pain in the right shoulder that occurred both at rest and with movement. Within a period of eleven days before and after the day of the nephrectomy, the patient had intramuscular injections of atropine sulfate (three injections of 0.5 milligram per milliliter), hydroxyzine hydrochloride (four injections of twenty-five milligrams per milliliter), pentazocine (four injections of fifteen milligrams per milliliter), and buprenorphine hydrochloride (one injection of 0.1 milligram per milliliter) into the right deltoid. Pain developed in the right shoulder on the tenth postoperative day and gradually increased. Physical examination of the right shoulder revealed a 15-degree abduction and 10-degree extension contracture and a winged scapula. Tender induration was palpable in the middle fibers of the deltoid, one centimeter anterior to the acromial angle. Assessment of the active ranges of motion demonstrated total elevation of 140 degrees bilaterally, external rotation of 45 degrees bilaterally, internal rotation to the eighth thoracic vertebra on the right and to the seventh thoracic vertebra on the left, and horizontal abduction of 100 degrees on the right and 130 degrees on the left. Radiographs showed normal findings except for evidence of the abduction contracture (Fig. 1). A diagnosis of myositis of the deltoid secondary to repeated intramuscular injections was made, and the patient was managed with nonsteroidal anti-inflammatory agents.
At the follow-up evaluation four months later, the patient reported pain in the anterosuperior aspect of the right shoulder with motion or when she lay on either side. The induration in the deltoid that had been palpated at the first examination had become a nontender longitudinal cord-like structure. Tenderness had developed over the supraspinatus tendon and the bicipital groove. Pain and insomnia persisted for an additional three months despite nonoperative treatment, and an operation was performed. On exposure of the acromial portion of the deltoid origin, a longitudinal groove in the superficial deltoid fascia was found one centimeter anterior to the acromial angle. A white fibrous band, one centimeter in diameter, was present in the muscle directly beneath the fascial groove. After transection of the fibrous band and maximum adduction of the arm, the transected edges separated three and one-half centimeters. The anterior part of the middle fibers of the deltoid was then detached from the acromion to allow examination of the rotator cuff. The supraspinatus and infraspinatus tendons appeared edematous and hyperemic. The bursal-side surfaces of both tendons were fibrillated. After anterior acromioplasty and bursectomy, the detached portion of the deltoid was reattached to the acromion. Histologically, the band consisted of hyaline-degenerated dense fibrous tissue with some atrophied muscle fibers without inflammatory cells. Postoperatively, the abduction contracture and the pain in the shoulder resolved, and function was completely recovered within four months. At the four-year follow-up examination, the patient reported no recurrence of the symptoms and the score according to the system of Constant and Murley5 was 84 points on the involved side and 86 points on the contralateral side. CASE 2. A thirty-two-year-old man was seen because of a one-year history of pain in the anterolateral aspect of the right shoulder with movement. He had started rock-climbing twice a month two years earlier. He had no history of intramuscular injection or trauma to the deltoid. Neither an abduction contracture nor a winged scapula was observed when the shoulder was at rest. Total elevation was 135 degrees bilaterally, external rotation was 50 degrees bilaterally, internal rotation was to the eighth thoracic vertebra on the right and to the fourth thoracic vertebra on the left, and horizontal adduction was 120 degrees on the right and 150 degrees on the left. The scapula winged and a groove appeared in the skin over the middle fibers of the deltoid one centimeter anterior to the acromial angle when the right shoulder was horizontally adducted. A firm band in the deltoid was immediately palpable deep in the skin groove. Tests were positive for the drop-arm sign, impingement sign15, and Hawkins-Kennedy sign10. The drop-arm test is positive when, after abduction of the shoulder to 90 degrees, the patient is unable to slowly lower the arm to the side (that is, he or she must drop it) or has pain when attempting to lower it. The impingement sign is elicited by standing behind the patient and passively elevating the arm in the scapular plane while stabilizing the scapula. Pain in the shoulder and apprehension are indicative of shoulder impingement. Hawkins and Kennedy modified the maneuver by forcibly internally rotating the arm after passively elevating the arm to 90 degrees. Although the patient could not grasp the left shoulder with the right hand when the right shoulder was adducted, he was able to grasp it by flexing the right shoulder 45 degrees, which is recognized as the positive opposite shoulder test18. Radiographs showed normal findings except for an osseous spur on the greater tuberosity. As the symptoms did not resolve after three months, an operation was performed. Three fibrous bands that were 0.3 to one centimeter in diameter were located inside the deltoid, 0.5 to 2.5 centimeters anterior to the acromial angle. These bands were transected, together with the muscle fibers between them. The anterior part of the middle fibers of the deltoid was detached from the acromion to expose the rotator cuff. Marked fibrillation of the entire width of the supraspinatus tendon and of the anterior half of the infraspinatus tendon was observed. There was a deep incomplete bursal-side tear of the supraspinatus tendon. After anterior acromioplasty, the damaged portion of the supraspinatus tendon was resected and its end was sutured to the greater tuberosity. Histologically, the band consisted of dense fibrous tissue containing some atrophied muscle fibers. Six months after the operation, the patient resumed rock-climbing. At a follow-up examination one and one-half years postoperatively, he was asymptomatic and the score according to the system of Constant and Murley5 was 94 points on the right side and 96 points on the left side.
Pain that extends from the neck and the shoulder to the arm is frequently reported by adults who have a deltoid contracture, although it is usually absent in children who have the condition1-4,6,8,9,12,14,16-20 . The causes of this pain have been hypothesized to be friction between the superior angle of the scapula and the trapezius, hyperextension of the anchoring muscles of the scapula, and hyperextension of the anterior aspect of the capsule and the labrum16. However, there has been little, if any, objective evidence to support these hypotheses, and the real cause of this pain remains unclear. Fibrous bands in patients who have deltoid contracture most often are seen in the middle fibers1,2,8,9,11-14,17-19, which consist of oblique short muscle fibers that are multipennate in form7. More specifically, bands are likely to appear in the posterior portion of the middle fibers, directly in front of the acromial angle. If the band formed in this area is short, the shoulder is tethered in the abducted and extended position, with the patient unable to touch the contralateral shoulder in the adducted position but able to do so in the elevated position (that is, the opposite shoulder test is positive)18. A tight band may cause anterosuperior migration of the humeral head, which may cause the rotator cuff to impinge against the coracoacromial arch (Fig. 2). This may be the mechanism underlying the development of subacromial impingement.
A deltoid contracture may conceal the typical clinical findings of subacromial impingement. Motion may not be painful and the supraspinatus tendon may not be palpable in a shoulder with an abduction contracture in which the greater tuberosity is located under the acromion. Also, the rotator cuff and the subacromial bursa are not visualized during transection of the fibrous bands, which has been recommended as the principal operative treatment for deltoid contracture4,12,14,18. Recently, Ko et al.12 reported the results of operative management of forty patients who had a long-standing deltoid contracture. Three of their patients, whose symptoms of deltoid contracture had developed when they were adults, had signs and symptoms of impingement and evidence of a tear of the rotator cuff when they were first seen. Anterior acromioplasty and repair of the rotator cuff had to be performed as a delayed secondary operation after release of the deltoid contracture. Those authors did not mention the mechanism of impingement or any association between deltoid contracture and impingement. Subacromial impingement can be a cause of shoulder pain in patients who have a deltoid contracture. Patients who have subacromial impingement should be assessed for restriction of horizontal abduction associated with scapular winging, which is consistently observed even in subtle forms of deltoid contracture. If subacromial impingement and deltoid contracture coexist, simultaneous operative treatment of both conditions can be considered.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
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