eMedicine Specialties > Orthopedic Surgery > Shoulder

Deltoid Fibrosis

Author: Mark Brodersen, MD, Assistant Professor, Department of Orthopedic Surgery, Mayo Medical School
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Updated: Jun 5, 2008

Introduction

Deltoid fibrosis is a disorder marked by intramuscular fibrous bands within the substance of the deltoid muscle. These bands lead to secondary contractures that affect the function of the shoulder joint. Scapular winging and secondary scoliosis may also be related to this condition. Deltoid fibrosis has been associated with fibrous contractures of the gluteal and quadriceps muscles and is likely a similar process.

History of the Procedure

Significant documentation of deltoid fibrosis began in the early 1960s. Isolated reports of the condition had been made before then, but not in the English-language medical literature. Following World War II, parenteral administration of antibiotics, antipyretics, and other drugs became increasingly common. Along with the increased use of intramuscular injections came the appearance of deltoid fibrosis and contractures, as well as problems in other muscle groups.

Problem

Deltoid fibrosis is part of a spectrum of fibrotic conditions that affect both upper and lower extremities. Such fibrotic conditions may involve 1 extremity or, in rare cases, may involve all 4 extremities. Contracture of a muscle may limit limb function or appearance, which may also cause significant social unease. Deltoid fibrosis is seen in people of all ages, but it has been reported primarily in children.

Frequency

Incidence in the United States has been low. Reports on small groups of patients with deltoid fibrosis have been made, but no large series has been reported in the U.S. All of the large series on this condition are from abroad. In certain areas of the world, contractures have become endemic. This has caused significant social problems, resulting in litigation in some districts in Japan. In Taiwan, where the condition is endemic, the prevalence rate is 10% in some areas.

Etiology

Deltoid fibrosis has most commonly been related to postinjection changes. Numerous drugs have been implicated as causative agents, including Dramamine, iron, penicillin (crystalline and oily), lincomycin, pentazocine/Talwin, hypodermoclyses, streptomycin, tetracycline, vitamins, and antipyretics.^1,2

Why some children and adults develop deltoid fibrosis is unknown. Most siblings of children with deltoid fibrosis do not develop this condition, even if they have had a similar number of injections. Chen reported on a series in which there was a 30% incidence in siblings.³ Chatterjee and Gupta reported on 17 patients with deltoid fibrosis who belonged to a certain segregated patriarchal ethnic group in Calcutta.⁴ They noted that children from other communities in central Calcutta did not develop deltoid fibrosis. These findings, as well as those from Taiwan and Japan, suggest the existence of constitutional and/or predisposing factors in the etiology of contractures.

Pathophysiology

The deltoid muscle has 3 areas of origin: the clavicle, the acromion, and the scapular spine. There is 1 site of insertion, the deltoid tubercle on the humerus. The anterior and posterior portions converge directly into the insertion site, whereas the middle portion is multipennate. The middle portion has 4 intramuscular septa that extend distally from the lateral acromion. They interdigitate with 3 septa that arise from the deltoid tubercle. The main action of the deltoid is abduction of the arm. The anterior deltoid also assists in forward flexion and internal rotation. The posterior portion assists with extension and external rotation.

Contractures of the deltoid have been reported in all 3 portions. They are seen most commonly in the middle portion. The second most common site for contracture is the posterior portion. These areas are involved most commonly because injections are placed there to avoid the cephalic vein anteriorly. Anterior bands occasionally are seen. Two portions, or even all 3 portions, have been reported to be involved with contracture.^{4,5,6,7,8,9,10,11}

Electromyelogram (EMG) findings have shown no activity in the involved muscle, but nerve conduction studies have been normal. Chen has shown that EMG abnormalities are observed not only in the involved muscle but also in the uninvolved muscles.^3,12 This suggests that the muscle initially is abnormal and is especially susceptible to injury and development of fibrosis.

Chen has proposed 3 possible mechanisms for the development of deltoid contractures.^3,12 These mechanisms are as follows:

• Direct disruption of the muscle by needle injection or myotoxicity related to the injected drugs.
• Myoischemia due to the volume of the injection, with local edema, fibrotic compression, and vascular damage. (Tissue edema promotes fibroblast activity and collagen production.)
• Fibrotic compartmentalization of muscle tissues, which may cause myoischemia and entrapment neuropathy. (Denervation may occur during the fibrotic process, with damage to the distal nerve fibers or motor end-plates.)

Repeated injection injuries and/or myotoxicity are believed to trigger fibrotic deltoid contracture by causing focal myositis and subsequent myopathic degeneration. Denervation occurs simultaneously from fibrotic compression or ischemia. Also, it is likely that injury occurs in connective tissue as well as in muscle. This could be caused by an enzyme deficiency in collagen degradation, an increased rate of collagen synthesis, genetic defects in the regulation of collagen biosynthesis, or an enzymatic defect in fibroblasts.

Some or all of these factors are undoubtedly at work, independent of muscle injury, as almost all series of deltoid fibrosis include patients who do not have a history of deltoid injections.

Presentation

History

• History of injections in and around the site of involvement
• Similar contractures in other parts of the body
• Family history of similar contractures
• Significant limitation of the activities of daily living

Physical examination

• Examine neck motion, looking for Sprengel deformity and other congenital abnormalities
• Examine shoulder and upper extremity to evaluate glenohumeral and scapulothoracic motion and stability
• Assess for winging of the scapula and freedom of scapular motion
• Look for evidence of contractures elsewhere in both the upper and the lower extremities
• Perform complete neurovascular examination
• Examine thoracic and lumbar spine, looking for scoliosis or chest wall abnormalities

The contracted portion of the deltoid determines the problems encountered by the patient. The shoulder is abducted when only the middle portion is involved. If the anterior portion is involved, the arm assumes a flexed and abducted position. If the posterior portion is involved, the arm is extended and abducted. As the arm is progressively extended or flexed, subluxation of the humeral head may occur. Most contractures are full thickness. However, a small group of individuals with only undersurface bands has been reported. These individuals experienced impingement and rotator cuff tears. Individuals in this group were skeletally mature.

Recurrent dislocation has been reported, as well as chronic labral injury. Radiologic evaluation of glenohumeral joint stability may be difficult because of changes in scapular position causing a relative overlap of the glenoid and humeral head. CT scanning may be required to adequately evaluate the status of the glenohumeral articulation.

In patients who are skeletally immature, flattening of the humeral head and changes in acromial morphology (drooping) may be seen. As the abduction contracture increases,¹³ the weight of the arm causes the inferior border of the scapula to rotate medially, resulting in winging of the scapula. Frequently, the skin may dimple, and a fibrous band may be palpable. Muscle aching about the shoulder girdle frequently accompanies the winging. Scoliosis secondary to more severe abduction contracture has been reported. Individuals usually present with inability to move the arm across the body. Abduction of the arm releases the tension of the fibrous band and allows cross-body movement.

Indications

Surgical treatment centers on the release of the contracted fibrous bands. The most commonly indicated cases for surgical treatment are those in which the abduction contracture at rest is greater than or equal to 25°. Patients should be at least 5 years old and should show evidence of progressive deformity during growth or changes in bony anatomy (eg, head flattening, changes in acromial morphology, widening of the acromioclavicular joint, scoliosis, narrowing of the thoracic cage). Most of these bony abnormalities may be exaggerated or underestimated, depending on the radiographic imaging method used and whether the bones are positioned adequately.

Fluoroscopic radiographs or CT scans may be required to appreciate fully the specific deformity. Ogawa reported that the humeral head deformity remained in juvenile cases, despite surgical resolution of the abduction contracture.⁵ Therefore, deltoid contracture in the young patient should be treated surgically when the patient is at an age that allows spontaneous correction of the bony deformity with growth. This decreases the risk of late arthritic changes due to humeral head incongruence.

No significant bony abnormalities were reported in adults. Hypertrophy of the deltoid tuberosity and cystic lesions of the acromion have been reported, but no specific bone or joint abnormalities have been identified. Indications for surgical treatment in adults should be based on symptoms of neck or shoulder girdle pain, as well as limitations in activities of daily living.

Contraindications

The usual contraindications for surgery apply, such as general health considerations that would make the patient unsuitable for general anesthesia. Local problems with the skin and soft tissues preclude surgical treatment. There are no other specific contraindications.

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