The Mystery of Growth

We might not think about our bones very often unless we break one. When we break a bone, the bone heals itself and begins to regrow.

But, wait a minute!!!

What if our muscles, tendons and ligaments turned to bone?

What if we formed a second skeleton on top of the one we already have? 

That's what exactly happens with Fibrodysplasia Ossificans Progressiva (FOP).

An FOP skeleton doesn't look like the ones we see at Halloween or the kind that hangs in an anatomy classroom. Instead of having lots of bones linked to one another with functioning joints, an FOP skeleton's bones fuse together, essentially forming a second skeleton out of the tendons, ligaments and muscles ~ a true metamorphosis. The skeleton is almost one solid piece, and sheets of bone exist where they should not.

The most common sign of FOP can be seen at birth: malformed big toes. Doctors aren't sure why this happens — it just appears as an early indicator of FOP. Aside from the malformed big toes, other initial signs of FOP usually show up in the early stage of life. One day, a large ‘lump’ suddenly begins to form on a child's body, usually in the ‘neck’ or ‘back area’. It can appear rapidly, often overnight and grows much faster than most tumours. It's warm to the touch, red and painful. A person's first reaction is often to assume it must be some sort of tumour — what if it's cancer? — but then the lump stops being painful, eventually gets smaller, and turns to bone — Normal Bone!!, but in the wrong place — where the body neither needs it nor wants it.

These lumps are called Flare-Ups (a sudden burst of fire/light; here, a symptom of a disease) and they appear all through the life of a person with FOP. Doctors aren't always sure what triggers them, but they do know that any kind of injury, even a small one, can cause a flare-up. For someone with FOP, a fall is not just a fall and the typical bumps & bruises of daily life are a major threat to the mobility and independence. If a person with FOP bumps his elbow or knee, bone could begin to grow there and lock the arm or leg for the rest of the life.

In general, for FOP patients, extra bone formation almost always starts at the neck, spine and shoulders. Only then does it move to the other joints. Eventually, people with FOP will probably lose most of their mobility. Joints lock and bones can twist into odd positions. Some people with FOP develop ‘scoliosis’— their spine twists. Often, the jaw fuses together either spontaneously or as a result of an injection for dental work, which makes eating and brushing teeth extremely difficult.

The skeleton will fuse into one position and in that posture the person with FOP will stay in for the rest of his or her life.

Any attempt to remove the extra (heterotopic) bone only leads to extra bone formation.

Only 700 people worldwide are known to have FOP, which makes this disorder extremely rare [source: IFOPA].

The skeleton of Harry Eastlack, (1933 – 1973), suffered from FOP [from the collections of the Mütter Museum, College of Physicians of Philadelphia] © A.B. Shafritz et al., New Eng. J. Med. 1996, Massachusetts Medical Society.