What is OI ?

What is Osteogenesis Imperfecta (OI)?

Osteogenesis Imperfecta (OI) is a genetic disorder that makes the bones of an individual break easily with little trauma or without any apparent reason.

The term Osteogenesis Imperfecta simply means Imperfect Bone Formation. Another name is Brittle Bone Disease.

Both male and females in all racial groups can be affected with this condition and the severity ranges from mild, moderate to severe.

The major cause of OI is as a result of a mutation (change) in the gene that produce the tissues responsible for bone formation and bone strength. This tissue is called Type I Collagen and makes up about 90% of bone. This tissue, Type I Collagen, is found not just in bones but in almost every organ of the body in varied proportions. You have greater amounts in the eye and teeth. Hence, although the chief manifestation of OI has got to do with bone problems, you have other manifestation in other organs- blue sclera, dentogenesis imperfecta, and hearing loss.
For bone problems, their bones break easily and they tend to suffer a lot of bone deformities. These deformities can affect any bone in the body.

Usually, bones of OI individuals experience frequent breaks during infancy through to puberty and decrease as the individual grows to adulthood.

Currently it has no cure but with good medical management and supportive mechanisms, individuals with OI live healthy productive lives.

How Is OI Inherited?

Osteogenesis imperfecta (OI) is a genetic disorder where there is a mutation (change) in the gene that produce Type I collagen. Most of the cases (90%) arise from a mutation of the gene that affects the protein in the main structure of Type I Collagen- Situation A. For the other cases (10%), there is a mutation in the gene that produces proteins that help in the formation of the structure of Type I Collagen- Situation B. Mutations of Situation A are inherited in a dominant manner whereas mutations in Situation B are inherited in a recessive manner. There is also the tissues responsible for bone formation and bone strength.

General Symptoms

Signs and symptoms of the most common forms of OI can be present at birth, or later in childhood.
There are chiefly 4 major symptoms:

  • Bone problems

These are due to a reduction in the mineral density of the bones.

  1. Fractures– that can occur in any bone but is common in the ribs, bones of the arms and legs. Comes with a lot of pain.
  2. Bone deformities
  • Chest- Barrel chest
  • Spinal curvature- Kyphosis, scoliosis
  • Pelvis- Coxa vara
  • Legs- Loss of funneling of the legs.
  • Eye problems

Blue Sclera(ie blue pigments on the normal white area of the eyeball)commonest eye finding. Others are Refractive errors, glaucoma

  • Brittle teeth (called Dentinogenesis Imperfecta or DI) are seen in 50% of people who have OI
  • Hearing loss

Other manifestations are respiratory and cardiovascular problems, brain invagination, short stature, triangular facies, loose joints, ligament laxity and muscle weakness are common.

How is OI Diagnosed?

OI can be diagnosed by

  • History- symptoms and signs
  • Physical examination
  • Investigations- X-rays, Genetic testing, skin biopsy, ultrasound scans (prenatally)

How is OI Treated?

There is no cure for OI, but there are ways to manage the symptoms to minimize fractures, bone pain and promote good health.

Management for OI takes a multidisciplinary approach. This is because of the different issues they could have.

Personnel include the Paediatrician/Internist, Orthopedic Surgeon, Ophthalmologist, ENT Surgeon, Physiotherapist, Occupational Therapist, Clinical Psychologist, Geneticist, Dietician, Nurse.

Symptomatic management

Fracture Care. Fracture Care includes casting, splinting and bracing broken bones can help them heal properly and reduce pain.

Surgery. Surgery is mainly used to correct bone deformities such as bowing in OI. The surgical procedure, known as rodding (metal rods insertion) of long bones, is used to control fractures and improve deformities that interfere with function. Both non-expandable and expandable rods are available.

Medications. Drugs that increase bone mineral density in children are used. These drugs are called Bisphosphonates and they have been proven to help reduce bone fractures and pain.

Healthy Nutrition. Healthy balanced diet is very important in the general health of an OI individual. Adequate intake of nutrients, such as Vitamin D and calcium is necessary to maintain bone health. Bad habit such as smoking, excessive alcohol and Caffeine should be avoided by OI individuals since it reduces bone density. Obesity and overweight should also not be encouraged in OI since it attributes to health issues.

Physical Therapy and Safe Exercise. Physical therapy is basically needed to increase muscle strength and increase mobility of an OI individual. It is very ideal to begin this therapy in infancy to help counteract the delay in motor skill development many children experience due to OI related muscle weakness. Adaptive devices may be needed. Swimming and water therapy are known to be an effective way to increase muscle strength and particularly well-suited for people with OI of all ages, as they allow independent movement with little fracture risk.

Orthotics: The use of Mobility aids such as walkers, crutches, canes and wheelchairs.

Hearing Aids: For those that end up with hearing loss, prescribed by the ENT Surgeon.

Crowning the teeth: For those with Dentinogenesis Imperfecta.

How Is OI Inherited?

Osteogenesis imperfecta (OI) is a genetic disorder. Most cases (90 percent) are caused by a faulty gene that reduces either the amount or the quality of type 1 collagen throughout the body. These mutations are inherited in a dominant manner. The other 10 percent of cases are caused by mutations in other genes that are inherited in either a dominant or a recessive manner.

Types of OI

Type I

  • Most common and mildest type of OI.
  • Bones fracture easily. Most fractures occur before puberty.
  • Normal or near-normal stature.
  • Loose joints and muscle weakness.
  • Sclera (whites of the eyes) usually have a blue, purple, or gray tint.
  • Triangular face.
  • Tendency toward spinal curvature.
  • Bone deformity absent or minimal.
  • Brittle teeth possible.
  • Hearing loss possible, often beginning in early 20s or 30s.
  • Collagen structure is normal, but the amount is less than normal.

Type II

  • Most severe form.
  • Frequently lethal at or shortly after birth, often due to respiratory problems. 
  • Numerous fractures and severe bone deformity.
  • Small stature with underdeveloped lungs.
  • Tinted sclera.
  • Collagen improperly formed.

Type III

  • Bones fracture easily. Fractures often present at birth, and x-rays may reveal healed fractures that occurred before birth.
  • Short stature.
  • Sclera have a blue, purple, or gray tint.
  • Loose joints and poor muscle development in arms and legs.
  • Barrel-shaped rib cage.
  • Triangular face. 
  • Spinal curvature.
  • Respiratory problems possible.
  • Bone deformity, often severe.
  • Brittle teeth possible.
  • Hearing loss possible.
  • Collagen improperly formed.

Type IV

  • Between Type I and Type III in severity.
  • Bones fracture easily. Most fractures occur before puberty.
  • Shorter than average stature.
  • Sclera are white or near-white (i.e. normal in color).
  • Mild to moderate bone deformity.
  • Tendency toward spinal curvature.
  • Barrel-shaped rib cage.
  • Triangular face.
  • Brittle teeth possible.
  • Hearing loss possible.
  • Collagen improperly formed

Type V

  • Clinically similar to Type IV in appearance and symptoms of OI.
  • A dense band seen on x-rays adjacent to the growth plate of the long bones.
  • Unusually large calluses (hypertrophic calluses) at the sites of fractures or surgical procedures. (A callus is an area of new bone that is laid down at the fracture site as part of the healing process.)
  • Calcification of the membrane between the radius and ulna (the bones of the forearm). This leads to restriction of forearm rotation. 
  • White sclera.
  • Normal teeth. 
  • Bone has a “mesh-like” appearance when viewed under the microscope. 
  • Dominant inheritance pattern

Type VI

  • Clinically similar to Type IV in appearance and symptoms of OI.
  • The alkaline phosphatase (an enzyme linked to bone formation) activity level is slightly elevated in OI Type VI. This can be determined by a blood test. 
  • Bone has a distinctive “fish-scale” appearance when viewed under the microscope.
  • Diagnosed by bone biopsy.
  • Whether this form is inherited in a dominant or recessive manner is unknown, but researchers believe the mode of inheritance is most likely recessive.
  • Eight people with this type of OI have been identified.

Recessive Forms of OI
Researchers have identified two forms of OI that are inherited in a recessive manner.

Type VII

  • Sometimes symptoms of this type are similar to Type IV OI in many aspects of appearance and symptoms.


  • Similar to l Type II or Type III OI in appearance and symptoms Normal white sclera.

Suggested OI support organization websites for more information includes: