Demystifying Osteogenesis Imperfecta (Brittle Bone Disease)

By Luke Kung’u

A spot check by the Newsline team gave a rather busy-than-normal day at the Orthopedic Technology Department. Curiosity drove the team to the Head of Department Mr. John Ondiege who expounded more on the day’s activities.

It was a clinic day for Osteogenesis Imperfecta patients, and the staff were busy issuing special wheelchairs. This is what Mr.Ondiege had to say about the disorder. Read on…

What is Osteogenesis Imperfecta?

Osteogenesis Imperfecta (OI) is a congenital and inheritable disorder that is caused by deficiencies in the synthesis of type 1 collagen in which bones are abnormally soft and brittle. It is also known as ‘Brittle Bone Disease’ or ‘Type 1 Collagen disease’. Although OI has prominent skeletal manifestations, other anatomical structures rich in Type 1 Collagen, such as joints, eyes, ears, skin, and teeth are affected as well.

OI is usually transmitted as an autosomal dominant, but in severe variants of the disease, the parents are normal and a fresh gene mutation or autosomal recessive inheritance is postulated. The hallmark feature is bone fragility, with a tendency to fracture from minimal trauma.

Kindly elaborate on the clinical features that it presents

Four major sub-types have been recognized:

Type I: Most common or mildest type; patient exhibits less collagen than normal, with little bone deformity, although the bones are nevertheless fragile. There may also be a bluish discoloration of the sclera of the eyes.

Type II: Most severe form, with improperly formed collagen. A baby has very short arms and legs, a small chest, and a soft skull. They may be born with fractured bones or may also have a low birth weight and lungs that are not well developed. Fractures are common; many babies usually die within weeks of birth.

Type III: Severe bone deformities, where infants are often born with fractures, however, discoloration of the sclera may not occur. It is compatible with long life, generally of below-average height. OI may have skeletal with or without respiratory problems and brittle teeth.

Type IV: Bones are fragile and sclera may be of normal color. The bone abnormalities are mild to moderate in severity, adults are shorter than average and may have brittle teeth.

In worst cases, the child is born with multiple fractures and does not survive. In less severe cases, fractures occur after birth, often from trivial violence. However, fractures unite readily, but in more severe cases marked deformities like curving of long bones, scoliosis, and short stature often develop.

What are the possible symptoms of OI?

The symptoms of OI vary greatly within and between types, they include:

• Easily broken bones

• Bone deformities, such as bowing of the legs

• Discoloration of the white of the eye (sclera), may be blue or grey

• A barrel-shaped chest

• A curved spine

• A triangle-shaped face

• Loose joints

• Muscle weakness

• Skin that easily bruises

• Hearing loss in early adulthood

• Soft, discolored teeth

How is OI diagnosed?

Diagnostic tests:

X-rays: These may show many changes such as weak or deformed bones and fractures.

Lab tests: Blood, saliva, and skin may be checked. The tests may include gene testing.

Dual Energy X-ray Absorptiometry scan (DXA or DEXA scan): A scan of the bones to check for softening.

Bone biopsy: A sample of the hipbone is checked. This test is performed under general anesthesia.

Are there possible treatments for OI?

The main goal of treatment is to prevent deformities and fractures. Optimal treatment improves the functional ability of the patient and promotes independence.

Some of the treatment procedures include:

Bisphosphonate medicines: These are medicines that help to strengthen bones, reduced bone pain, prevented new vertebral fractures, reshaped previously fractured vertebral bodies, and reduced the number of long-bone fractures. They may be administered orally or intravenously.

Fracture management: The lightest possible materials are used to cast and immobilize fractured bones. To prevent further problems, it is recommended that a child begin mobilizing the affected area as soon as possible.

Orthotic management: This may include bracing and splinting the affected extremities and spine.

Orthopedic treatment: e.g. Rodding. Metal rods are surgically inserted in the long bones to improve strength, hold them in place (stabilize) and prevent deformities of long bones.

Dental procedures: Treatments, including capping teeth, braces, and surgery may be needed.

Physical and occupational therapy: To address fine motor skills, such as buttoning your shirt or tying your shoes, increase muscle power, flexibility, and joint range of motion. Mobility devices: Wheelchairs, walkers, canes, or crutches can be prescribed to enhance mobility.