Osteogenesis Imperfecta (Brittle Bone Disease)
What Is Osteogenesis Imperfecta (OI)?
Osteogenesis imperfecta (OI) is a genetic disorder that prevents the body from building strong bones.
People with OI might have bones that break easily, which is why the condition is commonly called brittle bone disease.
What Causes Osteogenesis Imperfecta (OI)?
Osteogenesis imperfecta (os-tee-oh-JEN-uh-sis im-pur-FEK-tuh) happens because of a defect in the gene that makes the protein collagen. Collagen is an important building block of bones.
People who have OI are born with it. They either don't have enough collagen in their bones or have collagen that doesn't work as it should. This makes their bones weaker and more brittle than normal bones. It can also lead to bone deformities. (Deformed bones do not have normal shapes.)
The defect in the gene can be inherited from a parent. Kids with OI often have a parent who has the condition. Sometimes, the defect in the gene happens spontaneously at the time of conception.
What Are the Signs & Symptoms of Osteogenesis Imperfecta (OI)?
The severity of osteogenesis imperfecta can vary. Some people won't know they have it until they fall and break a bone. For them, the only symptom of OI might be an occasional broken bone. Other people can have many bone breaks without any obvious cause.
Signs of OI include:
- bones that break with no known cause or from very minor trauma
- bone pain
- bone deformity (such as scoliosis or bowlegs)
- a shorter stature
- brittle teeth (called dentinogenesis imperfecta)
- a blue, purple, or gray tint to the sclera (the whites of the eyes)
- triangular face shape
- hearing loss in adulthood
- loose joints
What Are the Types of Osteogenesis Imperfecta (OI)?
Doctors classify the different types of OI based on how severe the condition is. To date, 15 types of OI have been identified.
Most cases of OI have symptoms that fall into one of these four classifications:
Type I osteogenesis imperfecta — people with type I OI have less collagen than normal. This makes their bones fragile, but they don't have bone deformities. The first break usually happens when a child starts walking. Fractures typically decrease after puberty.
Type II osteogenesis imperfecta — babies with type II OI usually are born with many fractures, are very small, and have severe breathing problems. As a result, most will not survive.
Type III osteogenesis imperfecta — people with type III OI usually will be shorter than their peers, and may have severe bone deformities, breathing problems (which can be life-threatening), brittle teeth, a curved spine, ribcage deformities, and other problems.
Type IV osteogenesis imperfecta — people with type IV OI can have mild to serious bone deformities, short stature, frequent fractures (which may lessen after puberty), and a curved spine.
How Is Osteogenesis Imperfecta (OI) Diagnosed?
Besides a family history of OI, doctors look for frequent or unexplained bone fractures, dental problems, blue sclera (the white part of the eye), short stature, and other symptoms as signs that a child has OI.
They might also order tests like:
- X-rays, which can show fractures or healed breaks
- DNA tests, to identify the collagen gene mutation
- blood tests or urine tests, usually to make sure that other conditions, such as rickets, aren't causing the symptoms
- biochemical testing, which may include a skin sample to examine the collagen
How Is Osteogenesis Imperfecta (OI) Treated?
There's no cure for osteogenesis imperfecta. Treatment is based on a child's specific symptoms, and can include physical therapy and mobility aides, occupational therapy, medicine, and surgery. The goal is to prevent fractures, treat them properly when they do happen, preserve mobility and independence, and strengthen bones and muscles.
The treatment team might include a primary care doctor, an orthopedist, rehabilitation specialists, an endocrinologist, a geneticist, a neurologist, and a pulmonologist.
Preventing Broken Bones
Preventing bone fractures is key for people with OI. They can lower their risk of broken bones by:
- avoiding activities that put them at risk for a fall or collision, or put too much stress on the bones
- doing low-impact exercises (such as swimming) to build muscle strength and mobility and increase bone strength
When bones do break, it's important to treat them right away with casts, splints, and braces. Orthopedists (doctors who specialize in treating bone problems) might recommend using lightweight versions of these devices that allow some movement during healing.
Physical therapy (PT) can be helpful for many kids with OI. It can build muscle strength, which helps maintain function, promote aerobic fitness, and improve breathing. Kids who need them can learn how to use mobility aides and assistive devices. In younger kids, PT can help with motor skill development.
Doctors might prescribe bone-strengthening medicines to increase bone density and further reduce the chances of fractures. Some people will need treatment to maintain bone strength for the rest of their lives.
Sometimes, surgery is needed to repair a broken bone or fix a deformity. Surgeons also might place metal rods into long bones (like the femur, tibia, and humerus) to prevent breaks. Surgery also can correct dental problems from brittle teeth, and help with hearing problems.
Bone breaks due to OI usually lessen in early adulthood, although they can start happening again later in life.
Taking steps to prevent fractures — along with early, ongoing medical care — will help most people with OI lead healthy, productive lives.
For more information about osteogenesis imperfecta, visit the Osteogenesis Imperfecta Foundation (OIF) website.