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  • Writer's pictureRandon Hall, MD

What Exactly is Myositis Ossificans?

Injury: Myositis Ossificans

Understanding The Injury

Every once in a while we hear about athletes developing Myositis Ossificans (MO), but I think that there is the need for a clear and concise explanation. MO actually occurs secondary to a traumatic injury. The most classic case is when an athlete sustains a contusion to the muscle, such as the quadriceps (thigh). During the initial contusion injury, muscle fibers are disrupted and local bleeding occurs. Over time the local bleeding can develop into a blood collection called a hematoma. As the hematoma resolves, calcifications begin to form and new bone begins to develop within the tissue, which is the actual myositis ossificans. The calcifications begin to form over the period of a few weeks and can be quite painful. It is not exactly clear why this process develops, but it is thought that the more severe the contusion the higher the risk of this process occurring. In my experience, it also tends to occur more often when there are repetitive contusions to the same area. Although MO is fairly rare it can also occur with other traumas to different joints or muscles other than the thigh.

What's The Clinical PICTURE?

Typically the athlete will have history of a moderate to severe muscle contusion, most commonly in the thigh. They may also report multiple injuries to the same location. Usually, they will report a worsening of pain over the injured area that has developed 3-4 weeks after the injury. This should be notable, as a muscle injury should have shown significant improvement by this time. The MO can usually be seen on plain x-ray at 4 weeks time. However, other modalities such as ultrasound and MRI can be used to make the diagnosis as well as determine the stage of development of the bone. Within 1-2 month the athlete may feel a palpable mass with the affected area consistent with the clear development of the calcification within the muscle. The area can be very painful and very sensitive to the touch. The pain can be short lived or can last for months or even years. For example, an athlete can develop irritation of other structures such as tendons, bursa or nerves due to the development of the myositis ossificans with the soft tissue.

How is it Treated?

In general, early non-operative treatment is the best course of action for a muscle contusion and development of myositis ossificans. With an acute injury, it may be best to avoid heat and massage to the area as this may increase the blood flow and bleeding that can cause a worsening hematoma to develop. Therefore, it is usually indicated to ice after the initial contusion to potentially reduce the possible hematoma. Although physical therapy will be helpful, early aggressive therapy should be avoided to limit aggravation of injury to the muscle. Simple assisted range of motion is sufficient in the early stages. Once the MO has developed and matured stretching and strengthening of the affected muscle can be helpful to reduce any loss of range of motion and improve overall function. A strong anti-inflammatory medication called Indomethacin has also been suggested for a brief usage in the early stages, as it is believed to reduce bone formation. If the patient is having intractable pain surgery could be recommended. However, this process takes time to develop, and a premature surgery can result in recurrence of the process. Therefore surgical intervention should be reserved for at least 6 months to a year to ensure the MO will not recur after surgical removal.

Return to PLAY

Return to play after myositis ossificans can vary dramatically in length of time. Once the early stage has passed and the bone is more mature, there is less risk of additional injury and development of further hematoma. If the athlete has resolution of pain and the calcifications are stable they would be released back to play. Usually, additional padding such as a thigh pad would be used to further protect the area from re-injury.


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