Introduction:
Deltoid fibrosis is a clinical condition seen by the stiffness and unableness to move one’s shoulder. This condition occurs due to the thickening of the deltoid muscle triggered by various causes like infection, trauma, and injections. Although various causes can trigger the inflammatory reaction, the exact cause of deltoid fibrosis still remains unknown. Deltoid fibrosis is a part of the spectrum of fibrotic conditions which causes fibrosis of the deltoid extremities; these fibrotic conditions commonly affect either of the extremities but very rarely involve all four limbs.
What Is a Deltoid Muscle?
The muscle originates from three areas :
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The clavicle bone.
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The acromion process.
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The scapular bone.
Site of Insertion - The muscle inserts into the tubercle of the humerus.
The deltoid muscle is a large triangular-shaped muscle made by the fusion of three muscle fibers covering the upper arm and shoulder blade, giving a more circular shape.
The three fibers are anterior, middle, and posterior, namely. It is the primary muscle supporting the shoulder for flexion-extension and rotation of the upper arm and shoulder.
What Is Deltoid Fibrosis?
Deltoid fibrosis occurs due to the thickening or fibrosis of any one fiber of the deltoid muscle. Deltoid fibrosis leads to stiffening of the deltoid muscle restricting its movements. It can also occur due to systemic fibrosis, which usually affects the upper or lower extremities or sometimes both. Deltoid fibrosis as a disease became more significant after the 1960 cessation of the second world war, when the usage of intramuscular injections became more prominent and where the post-usage complications started showing up. Although the presence of deltoid fibrosis is said to be uncommon in adults, it’s most likely to be seen in children. In children, it occurs due to congenital or developmental disorders and trauma. In deltoid fibrosis, the stiffness of the muscle covering the shoulder blade or the scapula restricts the movement of the arm involved clinically, giving it a wing-like appearance.
How Does Deltoid Fibrosis Occur?
The most common sites of pathology involve the most common area of injections which includes primarily the middle fiber followed by the posterior fibers, although all three can be involved.
Recording the electrical activity of the muscle tissue using electromyography showed very minimal to no muscle activity. Still, nerve conduction is seen to be expected, proving that a muscle that is to be in an abnormal state initially becomes more prone to injury and fibrosis.
Chen et al. proposed three possible mechanisms for developing deltoid fibrosis being:
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Directly deranging the muscle fibers with needles and muscular toxicity due to the injected drugs.
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The muscle becomes ischemic due to the injection volume alongside edema, compression on the fibers, and vasocompression.
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Degeneration of the nerves occurring due to fibrosis leads to localized nerve damage.
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Hence consequently, needle injury and myotoxicity both together are involved in the formation of fibrosis, which is perceived to happen due to a lack of enzyme adequacy in collagen breakdown, increased collagen production, genetic defects in collagen biosynthesis, and defective enzyme of fibroblasts.
What Are the Causes of Deltoid Fibrosis?
The cause of deltoid fibrosis can be due to multiple reasons, which are the following:
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Trauma.
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Congenital or developmental defects.
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Improper delivery of parenteral medications.
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Increased frequency of needle usage.
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Toxicity of the drug-induced.
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Familial history of predisposition.
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Idiopathic.
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Medical conditions include - systemic sclerosis, hypertrophic scars, and keloids.
What Are the Drugs Which Cause Deltoid Fibrosis?
The usage of drugs through the intramuscular route is a significant cause of the development of deltoid fibrosis, and the medications with increased incidence are;
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Pentazocine.
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Meperidine.
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Penicillin.
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Antipyretics.
Where Is Deltoid Fibrosis Commonly Seen?
The incidence of deltoid fibrosis is seen predominantly in Asian countries, whereas deltoid fibrosis in the western world is generally low, only around ten percent. Here, the incidence age group usually ranges from six to twenty and is less common in adults.
Commonly seen in:
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Deltoid fibrosis is seen in people of all ages but mainly in children.
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Children with developmental problems.
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Also, people have a similar family medical history.
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Incidence is higher in Asians and lesser in the western world.
Deltoid fibrosis is an uncommon condition occurring in children predominantly, and it is known to be a condition of developmental disorders, so patients who develop deltoid fibrosis may have it due to genetic transfer of the disease.
What Are the Signs and Symptoms of Deltoid Fibrosis?
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Winging of the scapula or high riding scapula makes it a very important and clearcut feature of deltoid fibrosis, and the other features include:
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Lateral shift.
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Lateral Inferior rotation of the scapula.
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Contracture of flexion and extension of the glenohumeral joint.
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Pain and restricted movement.
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Dimpling of the deltoid skin.
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Palpable fibrous bands.
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Because it thickens the muscles of the hand, it prevents the movement of the arm, lifting and flexing the arm.
These clinical symptoms are the most common symptoms, which pave the way for the first-line diagnosis of the condition and prevent long-term negligence toward treatment.
Depending on the portion of fiber involved:
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Middle portion - Abducted arm.
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Anterior portion - Flexed and abducted arm.
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Posterior portion - Extended and abducted arm.
In severe conditions involving the anterior and posterior parts, subluxation and even dislocation of the humeral head can occur.
What Are the Other Relatively Occurring Conditions?
Deltoid fibrosis can be painful but is usually misdiagnosed with a frozen shoulder showing highly relatable signs and symptoms.
How to Diagnose Deltoid Fibrosis?
Deltoid fibrosis is diagnosed clinically, but MRI aids in removing any uncertainty and providing a clear picture. The MRI is the most often utilized radiographic imaging for diagnosing deltoid fibrosis because it is very tissue-sensitive imaging that supports the clinical diagnosis. Computed tomography (CT) is an additional imaging technique.
How Is Deltoid Fibrosis Treated?
Prevention is usually the best form of treatment, but in extreme cases deltoid fibrosis is treated in two ways
Non-Surgical Management :
The non-surgical medical management of deltoid fibrosis is done where the patient is put under observation followed by stretching of the muscles through exercises, this helps in the retraction of muscle stiffness, and pain management is achieved by using non-steroidal painkillers.
Surgical Management:
Although medical management is helpful, it is not very helpful in solving the issue permanently, and recurrence is often seen. In such cases, surgical management is usually preferred. The exact location of fibrosis is targetted, and surgery is performed. Following the surgical removal of the fibrotic chord, physiotherapy is used to rehabilitate the patient.
What Are the Outcomes of Deltoid Fibrosis?
The prognosis is usually favorable, with a recurrence rate of only 6%. Arm movements return fully, and scapular winging is seen to be reversed.
Conclusion:
Deltoid fibrosis, as discussed above, is the thickening of the muscle fibers. This condition occurs due to inflammation, causing restriction in the patient’s regular hand movements. But the best part about this condition is that it is more likely to be preventable and treatable. Patients’ age factor also plays an essential role in recovery and prognosis as it is seen commonly among patients of young age. With a diagnosis at an early stage and strengthening exercises, there is a good result and outcome.
