Osteogenesis imperfecta

Osteogenesis imperfecta (OI), also known as brittle-bone disease, is a genetic (inherited) disorder characterized by bones that break easily without a specific cause. An estimated 20,000 to 50,000 people in the US have this disease.

Causes 

The cause of osteogenesis imperfecta (OI) is believed to be due to a genetic defect that causes imperfectly-formed, or an inadequate amount of, bone collagen - a protein found in the connective tissue.

The disorder occurs in one out of 20,000 to one out of 60,000 live births. OI can affect males and females of all races.

Symptoms

The following are the most common symptoms for osteogenesis imperfecta (OI). However, each child may experience symptoms differently. Although symptoms may vary, generally they are used to classify the four forms of OI, each of which represents varying grades of severity of the condition.

According to the Osteoporosis and Related Bone Diseases National Resource Center, part of the National Institutes of Health (NIH), the types of OI and their symptoms include:

Type I:

• Most common
• Bones fracture easily
• Can usually be traced through the family
• Near normal stature or slightly shorter
• Blue sclera (the normally white area of the eye ball)
• Dental problems
• Hearing loss beginning in the early 20s and 30s
• Most fractures occur before puberty; occasionally women will have fractures after menopause
• Triangular face
• Tendency toward spinal curvatures

Type II:

• Newborns severely affected; frequently lethal
• Usually resulting from a new gene mutation
• Very small stature with extremely small chest and under-developed lungs

Type III:

• Tend to be isolated family incidents
• Very small in stature
• Fractures at birth very common
• X-ray may reveal healing of fractures that occurred while in the uterus
• Severe early hearing loss
• Loose joints and poor muscle development in arms and legs
• Barrel-shaped rib cage

Type IV:

• Can frequently be traced through the family
• Bones fracture easily - most before puberty
• Normal or near-normal colored sclera
• Teeth may or may not be involved
• Spinal curvatures
• Loose joints

The symptoms of OI may resemble other bone problems or medical conditions. Always consult your child's physician for a diagnosis.

Diagnosis

In addition to a complete medical history and physical examination, diagnostic procedures for OI may include a skin biopsy to evaluate the amount and structure of collagen. However, this test is complicated and not many qualified facilities are available to perform the procedure. It is not unusual for results of the biopsy to take up to six months.

Additional diagnostic tests include:

• X-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film
• An examination of the ear, nose, and throat to detect hearing loss

Treatment:

Specific treatment for osteogenesis imperfecta (OI) will be determined by your child's physician based on the following:

• Your child's age, overall health and medical history
• The extent of the condition
• The type of condition
• Your child's tolerance for specific medications, procedures or therapies
• Expectations for the course of the condition
• Your opinion or preference

To date, there is no known treatment, medicine, or surgery that will cure OI. The goal of treatment is to prevent deformities and fractures and allow the child to function as independently as possible. Treatments for preventing or correcting symptoms may include the following:

• Care of fractures
• Surgery
• Rodding (a procedure to insert a metal bar the length of a long bone to stabilize it and prevent deformity)
• Dental procedures
• Physical therapy
• Assistive devices, such as wheelchairs, braces, and other custom-made equipment

Management:

Management of the disease includes focusing on preventing or minimizing deformities and maximizing the child's functional ability at home and in the community. Management of OI is either non-surgical or surgical. Non-surgical interventions may include one or more of the following:

• Physical therapy
• Positioning aids - used to help the child sit, lie or stand
• Braces and splints - used to prevent deformity and promote support or protection
• Medications
• Psychological counseling

Surgical interventions may be considered to manage the following conditions:

• Fractures
• Bowing of bone
• Scoliosis - a condition that causes the back bones to curve
• Heart problems

Surgery may also be considered to maintain a child's ability to sit or stand.

Long-term outlook:

Osteogenesis imperfecta (OI) is a progressive condition that needs life-long management to prevent deformity and complications.

The interdisciplinary healthcare team helps the family to improve the child's functional outcomes and to provide support to the parents as they learn to care for their child's needs.

The Osteogenesis Imperfecta Society can be an important resource for parents of children with OI.