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How Fibrodysplasia Ossificans Progressiva (FOP) Works


FOP Treatment
Some clinical features of FOP: extra bone and malformed big toes
Some clinical features of FOP: extra bone and malformed big toes
Image courtesy Eileen Shore, PhD and Frederick Kaplan, MD, University of Pennsylvania School of Medicine; Nature Genetics, 23 April 2006, DOI: 10.1038/ng1783

You might wonder if FOP bone can be removed. Well yes, it can -- but that actually makes things worse. The bone will simply grow back, possibly with even more bone than before. Any kind of trauma to the body can cause a flare-up, resulting in new bone. Even injections into the muscle (like for vaccines or local anesthesia) can cause flare-ups, so you can see why a full operation might spark a traumatic reaction.

There isn't any real proven treatment for FOP, so doctors use medications to treat the symptoms of FOP. Reports are anecdotal -- they rely on the unscientific observations of people using the medications, rather than a double-blind clinical study. There aren't many people with FOP, so it's hard to get a large enough sample to conduct a study that could produce significant results. Eventually, it should be possible to design new medications to block the overactive receptor that triggers bone formation in FOP.

Some of the medicines that have been reported to be helpful are:

  • Corticosteroids like prednisone during the early part of a flare-up in major joint. Corticosteroids help decrease inflammation and swelling.
  • NSAIDs also reduce inflammation. If you've ever taken Advil or aspirin, you've taken an NSAID. COX-2 inhibitors (like Vioxx, which is no longer on the market, and Celebrex) are a particular kind of NSAID that seems to be very helpful in FOP treatment.
  • Aminobiphosphonates are anti-angiogenic, which means that they prevent the formation of blood vessels, which bone tissue needs to grow. They also keep too much bone resorption from happening by shortening the life span of osteoclasts. You would think that decreased bone resorption would be a bad thing in FOP, but it turns out that it seems to help people. Doctors aren't sure why.
  • Thalidomide is also an anti-angiogenic. It appears to modify immune system responses and functions in a way that might help with flare-ups. To some people, thalidomide brings to mind news stories of birth defects in the 1960s, after doctors gave it to pregnant women to help with morning sickness. However, thalidomide is supposed to be safe in people who aren't pregnant.

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For an adult with FOP, trying to stay as independent as possible can be a challenge. People with financial means or good insurance coverage could modify their homes to be wheelchair-friendly, making everything easier. For some people, it might be necessary to hire a caregiver.

In the next section, we'll look at some other rare bone diseases.


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