Osteogenesis imperfecta (OI) is a skeletal disease characterized by unusually fragile bones that break easily, often under loads that normal bones bear daily. This inherent weakness of the bones is due to a malfunction in the body’s production of the protein collagen. Collagen, of which there are at least 10 identifiable subtypes, is found in the connective tissues of the body and makes up a large portion of the bones and cartilage. It is the substance that holds the tissues together, providing strength and mass to the bones. For a person with OI, either the amount of collagen being produced is too little, or the quality being produced is poor. Either way, the bones of a person with OI are less dense and break easily. It is estimated that OI affects between 20,000 and 50,000 people in the United States.
OI is a genetic disease. The inheritance pattern is usually autosomal dominant. This means an affected person will have OI even though only one faulty gene has been passed along. This faulty gene can come from either parent, and it can affect either sex. Each child of an affected parent will have a 50 percent chance of developing OI.
Occasionally, a person will develop OI even though neither parent carried the faulty gene. This is called a spontaneous mutation. A person who develops OI will have the same chance of passing it on to a child as does someone who inherited the autosomal dominant gene.
There are four types of OI:
Type I:
This is the most common and mildest form of OI. It is autosomal dominant in its inheritance, but it may also result from a spontaneous mutation. People with Type I OI average nearly 40 fractures before puberty; however, they experience only a few fractures after puberty. The collagen in Type I OI is normal, but the amount produced is less than normal. Some features of Type I OI include:
- Fragile bones
- Triangular-shaped face
- Blue sclerae (whites of the eye)
- Hearing loss beginning in their 20s
- Scoliosis (curvature of the spine)
- Thin, smooth skin
- Loose joints
- Low muscle tone
- Brittle teeth
Type II:
Affecting approximately 10 percent of people with OI, Type II is the most severe form of this disease. The result of a spontaneous gene mutation, the collagen in Type II OI is improperly formed. The bones of people with Type II OI are extremely fragile and often have severe deformities. Type II OI frequently causes death at or shortly after birth.
Type III:
Type III OI affects 20 percent of the people who have OI. Usually the result of a spontaneous mutation, it is common for a person with this type to have experienced 100 fractures by the time he or she reaches puberty. There are often fractures present at birth and X-rays may even show healed fractures that occurred before birth. The collagen in Type III OI is improperly formed. Some of the characteristics of Type III OI include:
- Short stature (some people only grow three feet tall)
- Sclera have a blue, purple, or gray tint
- Soft bones that not only break easily but also bend
- Loose joints
- Poor muscle development
- Barrel-shaped ribcage
- Triangular face
- Scoliosis
- Poor tooth development, often causing teeth to be brittle and discolored
- Possible hearing loss
- Possible respiratory problems
Type IV:
The severity of this type of OI falls between Type I and Type III. It is inherited in an autosomal dominant manner, although it can also result from a spontaneous mutation. Fractures are most common in OI Type IV before puberty. The exception to this is in women, who after menopause experience a resurgence in the number of fractures. Typical characteristics of OI Type IV include:
- Below average height
- Scoliosis
- Mild to moderate bone deformity
- Triangular face
- Barrel-shaped ribcage
- Possible hearing loss
- Possible brittle teeth
- Loose, easily overstretched joints
Diagnosis
A doctor can often make the diagnosis of OI after a thorough physical examination using the above symptoms as guides, as well as a review of a family’s medical history. However, sometimes it is necessary to perform laboratory tests in order to confirm the disease. These tests will either be biochemical to test the collagen or molecular to examine the genetic pattern of the disease. The results of the lab test often take several weeks.
Treatment and management
The cure for OI has yet to be found. Because of this, treatment for the disease focuses on managing the symptoms, preventing complications, and developing and maintaining bone mass and muscle strength.
Immobilizing fractures:
Proper care and immobilization of fractures is essential to ensuring that bones heal properly. There are many methods for immobilizing fractures, including casting, bracing, splinting, and traction. Traction applies force to an affected body part, aligning the bone and holding it in position prior to casting or surgery. Traction is rarely used except for short (less than a day) periods of time. It can be used long-term, although this is rare. Your doctor will provide instructions on properly caring for your cast, brace or splint, so the bone may heal as quickly as possible.
Internal Fixation/Rodding Surgery:
Rodding surgery involves the insertion of metal rods through the length of long bones such as those in the leg. This is done to strengthen them and to correct and prevent deformities. This surgery is usually only performed on children when OI is severe enough to prevent walking.
Pain management:
Coping with and managing pain are essential if a person with OI is to lead a happy and productive lifestyle. The pain associated with fractures, joint deformities, and muscle contractures can be treated in a number of ways.
Heat/ice:
Cold packs can numb an area, decrease inflammation, and provide relief, while heat packs can bring relief to stiff muscles. Neither heat nor cold should be applied to a body part for more than 20 minutes at a time. Never apply ice directly to the skin.
Transcutaneous Electrical Nerve Stimulation (TENS):
This form of pain management involves using a small machine that emits an electrical pulse to block pain signals from being sent to the brain. This can provide relief for several hours. TENS machines can be purchased or rented; however, they should only be used under the supervision of a doctor or physical therapist.
Over-the-counter medications:
These pain relievers include aspirin, ibuprofen, and acetaminophen and are very effective at relieving pain. However, complications such as upset stomach or delayed blood clotting time can result from prolonged or excessive use. A doctor should be consulted if you plan on using these drugs continuously for more than two weeks. The doctor can also evaluate how these drugs might interact with any other medications you are currently taking.
Prescription medications:
A variety of medications can be prescribed to combat pain including other non-steroidal inflammatory medications (NSAIDs), topical ointments, and antidepressants. Antidepressants have been shown to play a role in pain relief by elevating a person’s mood. Studies have shown that when depression improves, it can lessen a person’s perception of pain.
Nerve block:
A nerve block is an injection of pain-relieving medication into the tissue surrounding an affected nerve. Depending on the type of medication and the amount given, nerve blocks can relieve pain anywhere from a few hours to a few months.
Exercise:
Exercise is essential in maintaining and promoting bone and muscle strength, which in turn can help prevent fractures. It also helps maintain a healthy body weight. The most common exercises recommended for patients with OI are swimming and water therapy. These exercises cause little stress on the bones and help to increase or maintain joint-wide range of motion for a patient with little risk of fracture.
Nutrition and diet:
While no food or vitamin supplement has been shown to reverse or prevent the symptoms of OI, proper nutrition is nevertheless very important. Regardless of which type of OI a patient has, he or she will have a tendency to develop osteoporosis, a disease in which the bones become very porous and fragile. Proper calcium and vitamin D intake is essential to maintaining strong bones and can help prevent osteoporosis. Reducing caffeine and alcohol intake, as well as not smoking, will also benefit a person’s bones and ensure that fractures heal properly and in a timely manner. A healthy diet also contributes to maintaining a healthy weight and a person’s overall health.
For more information on osteogenesis imperfecta, contact the following organizations:
Osteogenesis Imperfecta Foundation
804 West Diamond Avenue, Suite 210
Gaithersburg, MD 20878
301.947.0083
National Institute of Arthritis and Musculoskeletal and Skin Diseases
Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, Maryland 20892-3675
Phone: 301.495.4484 or 877.22.NIAMS (toll free)
TTY: 301.565.2966
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 9/15/2005...#9500
