Myositis ossificans

Myositis ossificans

Description, Causes and Risk Factors:

ICD-10: M61.5

Broadly, ossificans diseases of the muscle may be seen in either of two different forms: the myositis ossificans progressiva (MOP) and the myositis ossificans circumscripta called by others traumatic myositis ossificans (TMO), localized myositis ossificans, or fibrodysplasia ossificans circumscripta (FOC).

This is a rare disease of the locomotor system occurs during the period of growth and insidiously but inevitably brings about immobilization. It is characterized by the appearance of bone in muscle, tendons, fascia, and aponeurosis, and by the occurrence of exacerbation and remissions in the course of the disease, and of congenital bony anomalies.

If you have a bad muscle strain or contusion and it is neglected then you could be unlucky enough to get Myositis Ossificans. It is usually as a result of impact which causes damage to the sheath that surrounds a bone (periosteum) as well as to the muscle. Bone will grow within the muscle (called calcification) which is painful. The bone will grow 2 to 4 weeks after the injury and be mature bone within 3 to 6 months.

There are several theories on the etiology of myositis ossificans. It has been suggested this is merely an organizing hematoma. Other authors think the periosteum has been pushed into the muscle or the osteoblasts escaped the periosteum. Metaplasia of connective tissue cells is also a possibility.

There are several clinical subtypes of myositis ossificans:

    Myositis ossificans circumscripta refers to new extra-osseous bone that appears after trauma.

  • Progressive myositis ossificans is a rare, inherited disorder characterized by fibrosing and ossification of muscle, tendon and ligaments of multiple sites often in the upper extremities and back that is disabling and ultimately fatal.

  • Myositis ossificans is also a recognized complication of paralysis that occurs below the level of spinal cord injury.

Risk Factors May Include:

    Not applying cold therapy and compression immediately after the injury.

  • Having intensive physiotherapy or massage too soon after the injury.

  • Returning too soon to training after exercise.

  • Hypercalcemia is a known contributing factor to myositis ossificans. Hypercalcemia may be due to excessive vitamin D intake, hyperparathyroidism, aluminum toxicity or parathyroid carcinoma.


Symptoms may include:

    Myositis ossificans presents as a rapid enlargement and significant pain one to two weeks after injury.

  • The patient has swelling and warmth at the site.

  • Restricted range of movement.

  • Pain in the muscle when you use it.

  • A hard lump in the muscle.

  • Increased ESR (erythrocyte sedimentation rate) and SAP (serum alkaline phosphatase).

  • An X-ray can show bone growth.


The differential diagnosis of myositis ossificans includes other extraskeletal bone-forming lesions such as fibrodysplasia (myositis) ossificans progressiva and osteosarcoma.

There are not any specialtests for this injury. This can only be diagnosed (Dx) bylaboratory tests such as anX-Ray 2-6 weeks after theinjury occurred. Bone scans and CT scanscan help determine ifsurgery is necessary.

Grossly, the lesion tends to be well circumscribed. On cut surface, it is white, soft, and rather gelatinous (or hemorrhagic) in the center, and yellow-gray and firm with a rough granular surface at the periphery.

Microscopically, myositis ossificans is characterized by a distinct zonal pattern. This pattern is most conspicuous in lesions of three or more weeks' duration. There are three distinct zones: a central portion in which there is fibroblastic proliferation which can vary markedly in cellularity, pleomorphic characteristics, and numbers of mitotic figures; an intermediate portion where there is collagen and osteoid deposition among proliferating spindle cells, with early trabeculation of ossifying areas; and a peripheral zone of osteoid trabeculae rimmed by osteoblasts, with bone surrounded by loose fibrous tissue and atrophic fat. Characteristically, in myositis ossificans the bone formation is most prominent at the periphery of the lesion.


Initial treatment consists of ice, and bandages to relieve the pain and swelling. Further, stretching of the affected joint, maintaining strength or muscle control of the injured extremity, and modifying activity help restore function to the extremity. These may help reduce the incidence of myositis ossificans.

People suffering from the condition are advised to take complete rest. This is essential as rest plays a very important role in recovery. Patients are advised to restrict their movements and take rest as far as possible. This is continued until the pain subsides considerably. Immobilization aids in accelerating the healing process.

Initially a massage should be avoided to prevent further bleeding. But after a stipulated period, when the bleeding has stopped one can use massage therapy to alleviate the tension and stress of the affected soft tissues. A massage is indeed beneficial, as it provides considerable relief from the pain. It will help to regain the flexibility of the muscles. With massage therapy rehabilitating the injury may not be difficult, because it improves blood circulation and reduces the healing time. Regular massage is indeed the best way to increase flexibility and strength of injured muscles. The person will also be advised to wear a protective support such as foam padding or plaster.

Anti-inflammatory medications are also effective to treat myositis ossificans, as they relieve the discomfort of the patient. Indomethacin is beneficial as it helps to reduce the pain.

In case myositis ossificans is causing severe pain, even after months of injury, then surgical procedure is used to remove the bone. In some patients myositis ossificans does not allow normal joint motion and irritates the nerve. In such a case, surgery is used to eliminate the bone. Even if the condition is diagnosed early, surgery is not recommended as myositis ossificans is not "mature". Doctors generally wait for 6 to 12 months before considering surgical removal. It is likely to comeback, if it is removed before maturity.

With myositis ossificans, pain decreases with time. Rest along with medication will surely help to restore normal functioning of the injured muscle.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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