Deltoid Fibrosis

The deltoid muscle (see the image below) has three areas of origin: the clavicle, the acromion, and the scapular spine. There is one site of insertion, the deltoid tubercle on the humerus.

Deltoid muscle.

The deltoid muscle is divided into three portions: anterior, middle, and posterior. The anterior and posterior portions converge directly into the insertion site, whereas the middle portion has multiple branches leading to a central tendon. The middle portion has four intramuscular septa that extend distally from the lateral acromion and interdigitate with three septa that insert on 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 three portions of the muscle but are seen most commonly in the middle portion. The second most common site for contracture is the posterior portion. It is thought that these areas are involved most commonly because injections are placed there to avoid the cephalic vein anteriorly, though anterior bands are occasionally seen. Two portions, or even all three, have been reported to be involved with contracture.[3, 5, 6, 7, 8, 9, 10, 11]

Electromyography (EMG) has demonstrated decreased-to-absent activity in the involved muscle, but nerve conduction studies have been normal. Chen et al showed that EMG abnormalities are observed not only in the involved muscle but also in the uninvolved adjacent muscles.[12, 13] This suggests that the muscle is abnormal initially and is especially susceptible to injury and the development of fibrosis. A diagnosis can be made from the findings of fibrous cords on magnetic resonance imaging (MRI) of the deltoid muscle.[14]

Chen et al proposed the following three possible mechanisms for the development of deltoid contractures[12] :

• 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 endplates

Repeated injection injuries, myotoxicity, or both are believed to trigger fibrotic deltoid contracture by causing focal myositis and subsequent myopathic degeneration. Denervation occurs simultaneously from fibrotic compression or ischemia. It is also 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, in that almost all series of deltoid fibrosis studies include some patients who have no history of deltoid injections. Hogendoorn et al reported on infants with brachial plexus injuries during birth.[15] These individuals experienced contracture of the arm with muscle paralysis. The lack of innervation to certain muscles led to overcompensation by nearby muscles, along with osseous deformities. Scott et al described a patient with a deltoid contracture secondary to an osteochondroma of the scapula.[2]

Deltoid fibrosis has most commonly been related to post–IM injection events, with trauma, congenital factors, and progressive idiopathic factors also playing roles.[16] Antibiotics, antipyretics, and other commonly injected medications seem to influence contractures of the deltoid.[17, 18]

Although these factors seem to play a leading role, the exact cause of fibrous development is unknown. Chen et al found that siblings of affected children had similar contractures in only 30% of cases,[12] despite a similar frequency of injections.

Development of deltoid fibrosis is not limited to children. Multiple cases have been reported of fibrosis development in older adults who received frequent injections. However, Manske reported findings of contractures in infants with no history of injections.[19] These children had been exposed only to physical trauma and birthing complications. Chatterjee et al also examined multiple patients presenting with deltoid fibrosis that denied a significant history of IM injections, indicating that other factors must be contributing to fibrosis formation.[5]

It has been reported that progressive systemic sclerosis can cause deltoid fibrosis as well as its hallmark cutaneous manifestations.[20] An association with hypertrophic scar formation and keloid formation has also been noted with muscular fibrosis and contracture.[6]

In certain areas of the world, specifically Asian countries, contractures have become more common. In Taiwan, the prevalence has reached 10% in some areas. This growing frequency is thought to be due to increased use of IM injections as treatment for infections and fevers.[12, 21]

In the United States, the incidence of deltoid fibrosis has been low. Reports on small groups of patients with deltoid fibrosis have been made, but no large series have been reported in the United States. All of the large series on this condition are from outside the United States.

Several series have reported about a 6% incidence of recurrence. With distal release, Chen et al reported good outcomes in 100% of patients,[13]  and Ko et al reported good range of motion and pain relief in 96% of patients following surgical release.[22]

Patients who had distal release were evaluated with a Cybex dynamometer and were found to have no loss of strength compared with the contralateral side. Function returned to normal within 3 months.[13]

In general, the degree of preoperative contracture does not correlate with postoperative results.[14]  Whether the shoulder is treated with proximal or distal release, it appears that the rate of complications is low and that the great majority of patients see a return of full range of motion (ROM), excellent pain relief, and a resolution of scapular winging. The results of distal release have been found by several authors to be comparable to those of proximal release.[13, 22] Distal release avoids the stair-step deformity associated with a proximal release.

The following may be noted in the patient’s 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
• Pain near the shoulder and neck
• A dimple on the skin over the deltoid
• A fibrous, palpable band
• Scapular winging
• An inability to pull the arm fully down to the side of the body

Examine neck motion, looking for Sprengel deformity (high riding scapula) and other congenital abnormalities.

Examine shoulder and upper extremity to evaluate glenohumeral and scapulothoracic motion and stability.[15, 23]

Assess for winging of the scapula and freedom of scapular motion.[2]

Look for evidence of contractures elsewhere in both the upper and the lower extremities.

Perform a complete neurovascular examination.

Examine the 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. A bony projection can be present from the superolateral acromion and can indicate the formation of a traction enthesophyte. Computed tomography (CT) and magnetic resonance imaging (MRI) may be required for adequate evaluation of the status of the glenohumeral articulation and the muscular architecture itself.[16, 24]

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,[25]  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. An appropriate full physical examination should be conducted by an orthopedic surgeon.

No specific laboratory studies have been helpful in the evaluation or treatment of deltoid fibrosis. Diagnostic imaging (see Imaging Studies) is performed for initial evaluation. No other specific tests have been shown to be beneficial. Electromyography (EMG) may have research value, but it is not used routinely for patient evaluation in this setting.[26]  The histology of deltoid fibrosis shows dense fibrous tissue with some atrophied muscle fibers.[6, 27]

Plain radiographs are used initially to evaluate the glenohumeral and scapulothoracic mechanics. Fluoroscopic examination may follow if results are inconclusive.

If fluoroscopic examination is also inconclusive, computed tomography (CT) may be performed to evaluate any bone or joint abnormalities. CT scans provide a more comprehensive view of the glenohumeral joint than do plain films or fluoroscopic examination.

Surgical treatment focuses 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.

Fluoroscopy or computed tomography (CT) 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.[7]  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.

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 (ADLs). A derangement of shoulder mechanics occurs when a deltoid contracture and concomitant scapular winging is present. An increased winging angle of the glenoid alters the natural coordination between the deltoid and the rotator cuff, leading to mechanical consequences such as impingement and, possibly, rotator cuff tendinopathy and rotator cuff tears.

In a study by Huang et al,[28]  the relation between deltoid contracture and rotator cuff tears was evaluated. In patients with deltoid contracture, they found that age and the winging angle of the glenoid were predisposing factors for rotator cuff injury. They suggested that early surgery is necessary in older patients and in patients with an increased winging angle. Surgical release of the deltoid contractures aims to restore natural scapulothoracic kinematics to avoid rotator cuff injury or worsening of rotator cuff pathology and impingement.

A series by Yin et al supported simultaneous treatment of deltoid contractures and concomitant rotator cuff tears.[14]

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.

Medical treatment has involved observation, stretching, administration of nonsteroidal anti-inflammatory agents (NSAIDs), and some forms of physical therapy. However, none of these measures has been shown to be an effective form of treatment for deltoid contracture.

Preparation for surgery

In managing contractures, it is important to know the specific area of contracture to plan the appropriate approach. A single band may be approached via either a proximal or a distal incision. Fibrosis of more than one portion of the deltoid is best approached through a distal incision.[21]  Some predisposing indicators for surgical treatment include the following[8, 22] :

• Contracture of 25° or greater
• Patient aged 5 years or older
• Progression of contracture or appearance
• Pain and discomfort

Operative details

In most reports, proximal incisions have been used to expose the acromial attachment of the bands. Incisions may be transverse or longitudinal and are typically about 5-10 cm in length. Incisions must be made with caution to avoid the axillary nerve, which can be as close at 5 cm from the acromion through a deltoid longitudinal split.

Transverse incisions have been associated with keloid formation and unattractive scars. Longitudinal incisions may not allow adequate exposure of the entire deltoid area and may necessitate multiple incisions to perform adequate releases. Proximal release or resection of bands may leave large gaps in the deltoid muscle, causing loss of the natural shoulder contour and a stair-step–like deformity.

Minami et al transferred a portion of the posterior deltoid to fill in gaps, returning the shoulder to a more normal shape.[8]  They reported no failures with this technique. Groves and Goldner transferred the conjoined tendon of the coracobrachialis and the short head of the biceps to fill the defect in the deltoid by attaching the tendons to the remaining anterior deltoid and to the anterior acromion (limited Ober procedure).[6]

Following release or resection of the fibrous bands, shoulder range of motion (ROM) should be assessed. Ensuring adequate adduction is important. Occasionally, further release of smaller secondary bands or gentle manipulation of the shoulder is necessary to regain full ROM.

When the bands involve more than one portion or all of the deltoid, simple band release or excision is not always a good option. Manske reported on a case involving fibrosis dispersed throughout the entire deltoid.[19]  Instead of a proximal release, he used a distal incision about the deltoid tubercle, releasing the entire deltoid tendon from the tubercle. This approach yielded an excellent result.

Subsequently, Chen et al and Ko et al reported larger studies using distal release.[13, 22]  They noted excellent results as well, with fewer complications than previous proximal releases.

With proximal release, Minami et al advised using a stockinette to stabilize the arm across the body in an adducted position for 10 days following surgery.[8]  After this 10-day period, the patient should be advised to start movement and therapy to regain motion. Bhattacharyya also advocated this approach.[29]

Manske advocated the use of a plaster dressing to keep the arm adducted for 5 weeks, followed by an active exercise program.[19] Hang and Miller reported on multiple individuals without a postoperative immobilization period.[27] These patients showed full ROM at 2 years following surgical release.

With distal release, Chen et al used immediate postoperative ROM exercises, encouraging forced adduction.[13] Ko et al also used early ROM exercises, as well as a triangular sling for comfort.[22] A review of these studies suggests that neither a short period of immobilization nor early immediate mobilization clearly provides a better result than the other. Prolonged immobilization does not appear to be required for a successful outcome.

Proximal resection of the deltoid has been associated with multiple complications, including failure to release the deltoid contracture, keloid formation, and cosmetic deformities of the shoulder contour.

Patients undergoing distal release surgery experience fewer complications with good clinical results.[22] Owing to the high vascularization of the deltoid muscle, postoperative hematomas may form in proximal, distal, and intrasubstance releases. Careful hemostasis is obtained by means of electrocauterization in an effort to prevent hematoma formation and blood loss.[13, 30]

Neurovascular injury, infection, or other significant complications have not been reported. There is a risk of injury to the axillary nerve with an overaggressive proximal resection.