Brittle Bone Disease

Out of 100,000 people worldwide, about 6 to 7 people are affected by osteogenesis imperfecta (also known as brittle bone disease), a group of genetic disorders that mainly affects the bones. Relatively rare, this disorder causes a person to have fragile bones which may fracture easily, often from mild trauma or no apparent cause.

What causes osteogenesis imperfecta (OI) or brittle bone disease?

OI is caused by an abnormality in the genes that code for proteins that are involved in collagen production. As collagen is an important protein in our bones that keeps them strong, people with brittle bone disease have weak bones because they have poor quality collagen in their bones.

There are a few types of OI. The types can be distinguished by their signs and symptoms, although their characteristic features overlap. Increasingly, genetic factors are used to define the different forms of OI.

Who can get OI?

OI can be passed down by either one, or both parents to their child although there are some cases – usually with very bad OI – where OI is caused by a new genetic mutation. OI affects both girls and boys.

What are the signs and symptoms?

The main symptom of OI are broken bones, or fractures. Some babies with severe OI are born with fractures that have taken place in the womb or during delivery. Others have their first fracture soon after they are born.

Usually, young people with OI break bones easily. Just falling over can cause a fracture.

Thankfully, although the bones break very easily, they also mend easily. For reasons unknown, the risk of breaking bones becomes less as a person gets older.

Besides fractures, people with OI can also have :

* Loose joints/ ligaments
* Blue or grey colour of the ‘white’ of the eye - the sclera
* Discoloured or fragile teeth
* Lots of bruises
* Deafness from fractures of bones in the ear
* Hernias
* Excessive sweating

How is OI diagnosed?

The diagnosis is made by doctors from how many broken bones one has had. Other symptoms include blue or grey whites of the eyes. Sometimes someone with OI will have none of these symptoms and diagnosis can be very difficult.

X-rays can sometimes show up old fractures or changes in the bone structure that suggest the condition. But most of the time, x-rays and even bone density scans are surprisingly normal.

Genetic studies on skin samples (biopsies) can sometimes help confirm OI. But a 'negative' test does not rule the condition out. It just means you might have an unusual genetic change that has not been found before.

What are the treatments available?

Treatment is mostly good orthopaedic care when people with OI get a fracture. It is important that each fracture heals in a good position, and patients are encouraged to start moving around as soon as possible to keep their muscles and bone as strong as possible for a full recovery.

Bisphosphonates are being increasingly administered to increase bone mass and reduce the incidence of fracture.

For young people who get a lot of fractures, metal rods can be inserted into weak bones to help hold them together and stop them from breaking.

The care of OI patients is a multidisciplinary one. Team members may include an occupational therapist (OT), a physical therapist (PT), nutritionist, an audiologist, an orthopedic surgeon, neurosurgeon, lung specialist, and nephrologist, amongst others.