Deltoid fibrosis is a condition where intramuscular fibrous bands within lead to contractures and stiffness of the shoulder joint.
Deltoid fibrosis is part of the fibrotic conditions affecting both upper and lower limbs affecting a variable number of limbs.
It is seen in people of all ages, but it has been reported primarily in children. It is often associated with congenital/developmental defects, a genetic disposition or application of intramuscular injections.
The prevalence of the condition varies from very rare in USA to 10% in Taiwan.
Anatomy and Pathophysiology
The deltoid muscle originates from the clavicle, the acromion, and the scapular spine and inserts on the deltoid tubercle on the humerus.
It has three parts anterior, middle, and posterior.
The deltoid muscle is the main abductor of the shoulder. The anerior part participates in forward flexion and internal rotation whereas the posterior portion is involved in the extension and external rotation also.
Contractures of the deltoid, in order of frequency, are common in the middle, posterior and anterior part. More than one parts may be affected simultaneously.
Intramuscular injections, trauma, congenital factors have been mainly associated with causation.
But the exact cause is not known.
Studies have suggested that there could be muscle abnormality initially which makes them susceptible to injury and the development of deltoid fibrosis.
The fibrosis could develop by any of the following mechanisms
- Direct injury to the muscle
- by the needle
- toxicity of the drug.
- Volume of injection causing ischemia of selected portion
- Local edema
- Fibrotic compression
- Damage to vessels
- Fibrotic compartmentalization
- Muscle ischemia
- Entrapment neuropathy
In addition to muscle injury be the initial trigger for the event, injury to connective tissue could also act as same.
However, there are reported cases of deltoid fibrosis where there is no history of deltoid injections or trauma.
In children, flattening of the head of the humerus and drooping of acromion may be seen due to constant contracture.
With increased contracture, inferior border of the scapula rotates medially, causing the winging of the scapula. Fibrous band may caus dimpling of the skin.
In severe abduction contracture, secondary scoliosis may occur.
Clinical Presentation of Deltoid Fibrosis
Patient presents with a history of restriction of shoulder movement affecting the activities of daily living. The patient would typically complaint of inability to pull the arm fully down to the side of the body or across.
A complaint of pain near the near the shoulder and neck may be present.
On examination, one may notice a dimple over the deltoid skin.
Palpation would reveal a fibrous palpable band.
Patient should be enquired for the history of injections, similar contracture in other parts of the body and a family history of similar contractures.
Depending on the part of the deltoid involved, the limb of the patient may be
- Abducted – Middle portion
- Flexed and abducted – Anterior portion
- Extended and abducted – Posterior Portion
In severe cases involving anterior or posterior parts, the subluxation/dislocation of the humeral head may occur.
Examination should look for high riding scapula [Sprengel deformity] or other abnormalities like scoliosis or chest wall abnormality.
Motion of neck, glenohumeral joint and scapula should be assessed.
Winging of the scapula and freedom of scapular motion should be noted.
Look for evidence of contractures elsewhere in both the upper and the lower extremities.
Changes in position of scapula may cause radiographical assessment difficult requiring CT or MRI. CT and MRI would reveal typical bony changes discussed in pathophysiology.
The treatment of deltoid fibrosis is surgical. Medical treatments like stretching or physical therapy are not helpful.
The treatment consists of the release of contracted, fibrous bands.
The surgical treatment should be considered in
- Contracture > 25 degrees
- Age> 5 years
- Progressively increasing contracture
- Painful contracture
Fibrous bands should be released or resected.
If more than one portion of the deltoid is involved, releasing entire deltoid tendon provides better results.
The arm is immobilized across the body in adducted position for about two weeks after the surgery. After this patient is put on physical therapy and movements are started.
- Postoperative Keloid formation,
- Postoperative hematoma
The majority of patients have pain relief, a return of full range of motion and a resolution of scapular winging.
About 6% recurrence has been reported.
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