Guidebook Home

Table of Contents

Preface

Introductory Comments

General Questions About FOP

Genetics of FOP

How FOP Affects the Body

Care and Treatment

Activities

Feelings About FOP

Helpful Addresses

Family Resources

Ideas for Independence

Medical Articles

Acknowledgments and Contributions

HOW FOP AFFECTS THE BODY

What are the lumps that appear on the body?
Soft lumps appear spontaneously on the neck and back as early as the first year of life. The lumps may be very small or quite large and may appear overnight. Occasionally the lumps disappear but more commonly they mature to form a piece of bone. Although the bone has all of the appearances of normal bone-- complete with marrow-- it forms in places where it should not form, such as in muscles, tendons, and ligaments. The process completely replaces these structures with bone. The lumps initially are soft, often painful, and may be warm to touch. After they turn into bone, they often stop hurting though they still may be a source of discomfort due to pressure over those areas. Once the lumps turn into bone, they form a part of a person's body and will not go away.They occasionally may seem to change their shape and size, much like the bony bump on the outside of a broken bone.

When the soft lumps first appear, they may not be recognized and diagnosed as FOP and may be mistaken for tumors or cancer. Often the lumps are biopsied and misdiagnosed. Frequently, the surgical trauma of the biopsy leads to additional bone formation at that site.

FOP affects mobility because the body's joints, such as the knees or the elbows, connect the bones and aid in movement. In FOP, extra bone replaces the ligaments (which cover the joints), as well as muscles and tendons (which move the joints). Consequently, movement in areas affected by FOP becomes difficult or impossible.

What is a flare-up and is it painful? Is FOP always painful?
A flare-up occurs when the body starts to generate new bone. No one knows what initiates this process, but once it begins, it leads to tissue swelling and much discomfort. Flare-ups are usually painful. Sometimes the individual will not feel well and may develop a low-grade fever. While there is no medication or therapy that can stop the process of bone formation once it has begun, a physician can prescribe medicine to help relieve the pain. A single flare-up may continue for as long as 6-8 weeks. However, major overlapping flare-ups may occur in which pain does not subside as quickly. If your child is in pain, consult your child's physician about medication to ease the pain and alleviate some of the inflammation. When a flare-up is in progress, joint stiffness may occur overnight. One should not think that a piece of bone grew overnight. The stiffness comes from swelling and pressure inside the muscle during the earliest stages of new bone formation. A more chronic stiffness at night may arise from pressure over a bony area or from an unusual position during sleep. Some people find that a waterbed or air mattress is helpful.

Many people have noted that flare-ups in adults are different in character from those that occur in children. It appears that children tend to have more nodular flare-ups (lumps), while adults have more sheet-like flare-ups (swelling of the whole limb) without the formation of distinct nodules. Although these differences have been noted, scientists do not yet understand the reason these different patterns may occur. Although one type of flare-up may be more common than another at a particular age, either type can occur in anyone who has FOP.

Most people find that the pain subsides when a flare-up is over; it appears that it is the process of extra bone formation, rather than the extra bone itself, that usually leads to pain. FOP is not always painful.

Are all aches and pains cause for serious concern? How do I know whether an ache or pain is associated with FOP?
Even with FOP, a person can still have normal aches and pains. The best rule with FOP is to do what feels comfortable. Sometimes a hurt or ache is the body's way of telling us that we are doing too much. In FOP, it is a good idea to avoid those activities or positions that cause discomfort. When muscles are stretched, they often react by pulling back in the opposite direction, creating tension in the body. In some ways, it is like stretching a rubber band; the more it is stretched, the more it pulls back. This causes additional strain on the body. The key with FOP is to avoid activities that cause pain or are likely to lead to injury.

Most of the time, it is easy to recognize the clinical features of a flare-up without any special tests. However, if there is a doubt as to whether the pain is related to a flare-up or some other cause, there are scientific/diagnostic tests that can help.

FOP flare-ups most commonly lead to the formation of out-of-place extra bone (heterotopic bone). Early during the development of a lesion, an X-ray will show only soft tissue swelling. An X-ray at a later stage may show the bone that has formed. A bone scan is a test that can be performed at most hospitals and can show new bone formation early in the course of a flare-up.

What physical variations are seen from person to person?
Most people who have FOP have similar features, particularly malformation of the great (big) toes noticed at birth and heterotopic bone formation which progresses throughout life. However, much variation exists from person to person. The largest variation seen is the timing and rate of extra bone formation. For example, one person with FOP may lose motion in the hip during the first decade of life, while another person may still have normal mobility into adulthood. Another common variation includes the severity of malformation. For example, an elbow could be fixed in a closed position, putting the hand permanently across the chest, or the elbow may be left with some range of motion. Even the first possible indicator of FOP, the malformation of the great toes, does not always manifest itself in the same ways. A very small percentage of people with FOP have normal-appearing toes at birth with arthritic-like changes in the toes by ten years of age. In those patients, the first sign of FOP is a soft tissue lump that turns to bone.

In summary, the most common features of FOP are malformations of the toes and formation of heterotopic bone. Variations may occur in the type and extent of great toe malformation, as well as the rate and extent of extra bone formation. These differences in extra bone formation largely determine the timing and ultimate position of joint deformity. No one is able to fully explain the reasons for these variations.

Why do the limbs swell occasionally?
Swelling is a common problem in people with FOP and may result from different causes. First, the limb may swell due to an FOP flare-up. It is typical to see swelling that is highly localized and nodular in the upper limbs, often during childhood flare-ups. In adults, this may involve sheet-like swelling of the whole limb as opposed to the lumps which are seen in children. More diffuse, sheet-like swelling is more commonly seen in the lower limbs. While these are typical patterns, either type of swelling can occur at any age.

Second, the restricted movement of people with FOP can result in a lack of pumping action within the ossified muscle and can cause blood and tissue fluids to pool in the limb. The blood will remain in the muscle instead of being pumped along, hence, the swelling. Third, newly-formed bone can press on veins and lymphatics, the channels which carry blood and tissue fluid back to the heart. Pressure exerted by extra bone on these vascular channels can obstruct the flow of body fluids and cause swelling. These two explanations may explain examples of chronic swelling.

Finally, and less likely, is the formation of a blood clot. While a blood clot is rare, it is a serious problem. In order to prevent blood clots, it is suggested that the individual wear support stockings and contact the physician to determine if aspirin or a more powerful blood thinner is recommended. When the cause of the swelling is unclear, special tests-- such as bone scans, ultrasound, CT scans, or MRI scans-- may be necessary to determine the cause of the swelling so that specific treatment can be prescribed.

Will a person with FOP be able to eat if the jaw becomes fused?
Extra bone can form near the jaw, making it difficult to chew or get food into the mouth. Most people with fused jaws find that they can still eat food that is cut into small pieces, such as meat, cereal, bread, and cooked vegetables. Soft foods like pasta and mashed potatoes are also easy to eat. Others find that they can still eat anything that they want to eat. Nancy Sando, a member of the IFOPA, has written a book calledWhipping a Whopper, a special recipe booklet with creative hints on blending foods. If you would like a copy, please contact the International FOP Association. Sometimes, an FOP flare-up in the jaw or chin area may make it difficult to eat, or eating may aggravate the flare-up. In these cases, a person with FOP may need to take special high-calorie dietary supplements such as Ensure, so that body weight can be maintained. In very extreme cases a jaw fusion, a person with FOP may wish to consult a dental professional called a prosthodontist about whether a procedure called enameloplasty would be beneficial. Enameloplasty is a painless procedure in which a very small portion of the enamel is removed in order to create a slightly larger opening of the jaw.

Why does spinal curvature occur in some people who have FOP? What should be done about it?
Spinal curvature (scoliosis) may occur in people who have FOP as a result of asymmetric (unequal) heterotopic bone formation around the spine. If one side of the body is more restricted than the other, the resulting uneven growth results in spinal curvature. When this occurs, it usually develops early in life. It is less likely to develop in adolescents or adults, although it may progress rapidly during this time if it is alreadypresent. After bony bridges form, they restrict normal skeletal growth as the rest of the body continues to grow. Surgical intervention is not recommended because it does not successfully correct the problem and often leads to severe complications, such as flare-ups of FOP in other areas.

Is there a relationship between FOP and hearing impairment?
Hearing loss has been reported as a variable feature of FOP. One hundred and two patients who have FOP were surveyed by mail in order to determine the nature and prevalence of hearing disorders associated with FOP. Fifty-four surveys were completed (53%) response. Out of those responses, 28 (52% of respondents) reported a hearing problem while 26 (48% of respondents) reported no hearing problems. Six of those who responded were males and 22 were females. Hearing loss occurred in both ears in 19 patients. Most patients reported conductive hearing loss, but there were several documented cases of hearing loss due to involvement of the nerves responsible for conducting sound to the brain. Six patients wore hearing aids, and all reported improvement in hearing with the use of these devices. Two patients felt that their hearing loss was associated with FOP flare-ups of the jaw. Although there was no direct association between hearing loss in people with FOP and childhood ear infections, it is important to remember that all children have a high liklihood of ear infections that can affect hearing. Therefore, it is important that earaches and other hearing problems in children with FOP be promptly evaluated and treated, as hearing loss from ear infections is a preventable problem in all children. Loss of hearing occurs in a significant portion of patients who have FOP. Consideration should be given to undertake routine hearing studies.

Is swelling underneath the chin related to FOP?
An FOP flare-up can occur occasionally underneath the chin. This type of flare up occurs in about 10% of people who have FOP. The swelling can be mistaken for an allergic reaction, an abscess, or the mumps. It can press up on the base of the tongue, sometimes making it difficult to swallow. The lesion should not be manipulated, as that may cause more swelling. Sometimes this type of flare-up can cause difficulty with breathing, especially at night. Special precautions such as elevation of the head of the bed or monitoring may be needed. A brief course of steroids (prednisone) may be helpful. The steroids should be used for only a few weeks until the swelling resolves. This medication is generally not helpful in other types of flare-ups, and prednisone should not be used on a continual basis, as it does not prevent flare-ups from occurring.

If a person with FOP begins to have a flare-up underneath the chin, a doctor should be contacted so that steroids can be prescribed to help decrease the swelling. After the swelling subsides, people are sometimes left with a little knot of bone underneath the chin.

As with any FOP flare-up, swelling underneath the chin does not necessarily have to present a major health hazard. Several patients have noted a hard lump underneath the chin which they believe was related to FOP; however, it did not cause any health problems. Therefore, as with any FOP flare-up, the best approach is to have the flare-up evaluated by your local physician to determine if it is likely to pose any serious health hazards.

Does FOP feel the same all of the time? Does the weather have any effect on the condition?
The weather can affect how anyone's body feels. Some people do not feel as comfortable when it is cold or damp. Others are more uncomfortable when it is hot. Still others do not notice any difference with a change of weather or season. People who have FOP do not seem to prefer a particular weather, season, or climate.

What is the life span of someone who has FOP?
People who have FOP can live a long life. Many individuals who have FOP are otherwise in good health. Breathing complications from ribbons of bone that encircle and immobilize the chest, or severe malnutrition created by eating difficulties are factors which can limit the life span of affected individuals. However, most people who have FOP live into adulthood. There are adults who are now in their 50s, 60s, and even 70s.

Scientists at the University of Pennsylvania have undertaken a study to examine possible cardiopulmonary complications in people with FOP. Extra bone can create additional stress on the body, for instance making it harder to breathe when one has a cold or the flu. All infections in people with FOP, and particularly respiratory infections, should be treated aggressively with antibiotics when the first symptoms appear.

Is there any evidence of heart dysfunction in people who have FOP?
Extra bone formation in the chest region in patients who have FOP limits the ability of the chest wall to expand during breathing. Pulmonary complications are believed to play a role in the shortened survival of some FOP patients. While extra stress on the heart might be an expected long-term result of the severe restrictive disease of the chest wall, there has been no evidence of established heart dysfunction in patients who have FOP. In order to study this better, 25 patients with FOP ranging in age from 5 to 55 years volunteered to participate in a study at the Second International FOP Symposium. History, physical examination, pulmonary functions, electrocardiogram, and echocardiogram studies were performed on each patient. Although there was severe limitation of expansion of the chest wall, physical examination of the heart and lungs appeared normal. There was no evidence of heart failure in any patient. Ten of the patients had slight evidence of electrocardiographic abnormalities indicating increased stress on the right side of the heart (the part of the heart chamber that pumps blood to the lungs). Only one of these ten patients was under 13 years of age. All patients had extremely limited chest expansion, and lung capacity was severely reduced. However, the flow of air through the lungs was relatively normal despite the fact that the volume of air was reduced. Despite the limited capacity of the lungs to carry oxygen, the blood was well saturated with oxygen. The only abnormalities seen on the electrocardiogram were that there was indicated stress on the right side of the heart. Those patients were generally older and had significantly longer duration of FOP symptoms than those who did not have similar electrocardiogram findings. The presence or absence of scoliosis had no substantial impact on whether or not there was any evidence of electrocardiographic abnormalities.