Pediatric Fibrodysplasia Ossificans Progressiva (Myositis Ossificans) Treatment & Management

Flare-ups of fibrodysplasia ossificans progressiva (FOP) are sporadic and unpredictable, and the rate of individual disease progression widely varies. Several large studies on the natural history of fibrodysplasia ossificans progressiva have confirmed that predicting the occurrence, duration, or severity of an fibrodysplasia ossificans progressiva flare-up is impossible, although characteristic anatomic patterning has been described.

A brief description of agents to be considered during a fibrodysplasia ossificans progressiva exacerbation is below. For a complete description, including dosing and potential major side effects, refer to the current treatment guidelines at International Fibrodysplasia Ossificans Progressiva.

Flare-ups

Widespread favorable anecdotal reports from the fibrodysplasia ossificans progressiva community suggest that a brief 4-day course of high-dose corticosteroids, started within the first 24 hours of a flare-up, may help reduce the intense inflammation and tissue edema seen in the early stages of the disease. The use of corticosteroids should be restricted to the extremely early symptomatic treatment of flare-ups that affect major joints, the jaw, or the submandibular area. Corticosteroids should not generally be used for the symptomatic treatment of flare-ups that involve the back, neck, or trunk due to the long duration and recurring nature of these flare-ups and the difficulty in assessing the true onset of such flare-ups.

The dose of corticosteroids depends on body weight. A typical dose of prednisone is 2 mg/kg/d, administered as a single daily dose for no more than 4 days. The potentially dangerous nature of flare-ups in the submandibular region may dictate a slightly longer use of corticosteroids with an appropriate taper for the duration of the flare-up or until the acute swelling subsides.

When prednisone is discontinued, a nonsteroidal anti-inflammatory drug (NSAID) or cox-2 inhibitor (in conjunction with a leukotriene inhibitor) may be used symptomatically for the duration of the flare-up.

The use of mast cell inhibitors and aminobisphosphonates are less well-defined and should be used at the physician’s discretion.

Pain management

Many fibrodysplasia ossificans progressiva flare-ups, especially those around the hips and knees, are extremely painful and may require a brief course of well-monitored narcotic analgesia in addition to the use of NSAIDs, cox-2 inhibitors, and oral or intravenous glucocorticoids. Other types of transient pain syndromes may be caused by neuropathies resulting from acute flare-ups, transient bursitis, inflammation of osteochondromas, arthritis, and muscle fatigue.

Muscle relaxants

Areas of relatively healthy skeletal muscle bordering the acute fibrodysplasia ossificans progressiva lesion are subject to metabolic changes that lead to muscle spasm and fiber shortening. The judicious short-term use of muscle relaxants such as cyclobenzaprine (Flexeril), metaxalone (Skelaxin), or Lioresal (Baclofen) may help to decrease muscle spasm and maintain more functional activity.

Attempts to surgically remove heterotopic bone risks provoking explosive and painful new bone growth. Biopsies of fibrodysplasia ossificans progressiva lesions are never indicated and may cause additional heterotopic ossification.

Falls suffered by patients with fibrodysplasia ossificans progressiva can lead to severe injuries and flare-ups. Patients with fibrodysplasia ossificans progressiva have a self-perpetuating fall cycle. Minor soft tissue trauma often leads to severe exacerbations of fibrodysplasia ossificans progressiva, which result in heterotopic ossification and joint ankylosis. Mobility restriction from joint ankylosis severely impairs balancing mechanisms and causes instability, resulting in more falls. Compared with people who do not have fibrodysplasia ossificans progressiva, falls in those with fibrodysplasia ossificans progressiva are more likely to result in severe head injuries, loss of consciousness, concussions, and neck and back injuries due to the inability to use the upper limbs to absorb the impact of a fall and to anatomic abnormalities of the cervical spine in individuals with fibrodysplasia ossificans progressiva.

For children, redirection of activity to less physically interactive play may be helpful. Complete avoidance of high-risk circumstances may reduce falls but may also compromise a patient’s functional level and independence and may be unacceptable to many.