Osteogenesis Imperfecta

Dr.Ijaz Wazir

Historical Background

Osteogenesis means formation of bone

Imperfecta is Spanish for not perfect

Found in Ancient Egyptian Mummy from 1000 BC

Osteogenesis Imperfecta first used in 1895

Also called

Brittle Bone disease

Glass Bone disease

Ekman Lobstein syndrome

Epidemiology

• OI is defined as a congenital disorder of type 1 collagen.The gene for OI is located on chromosome 17.There is amino acid substitution which makes the collagen defective.

• About 85 to 90 % cases are autosomal dominent and 10 to 15 % cases are autosomal recessive.

• Bones,teeth,ligaments,skin and sclera are affected.

Epidemiology

• In OI, defective collagen means that the bones are extremely fragile and can fracture as a result of everyday movements.

• Simple movements such as opening a door or turning over in one’s sleep can cause these fractures.

Inheritance of OIThe pattern of inheritance in many

families with OI is autosomal dominant.

Each and every child of an affected parent has a 50% chance of inheriting the faulty gene and of having OI.

However, there are several hundred different mutations which can give rise to OI and many people with OI have no family history of the condition. This can be a result of spontaneous genetic mutation or been inherited in a different way

Inheritance continued

About 85%-90% of OI cases that are inherited are inherited in dominant manner. There are some rare instances where the disorder is recessive an autosomal however. The different inheritance patterns may also deal with slightly different genes.

35% of OI cases are a result of spontaneous mutations, while the others come from parents affected by OI or parents who are carriers.

Incidence of OI

• The world wide incidence of OI is 1 in 20,000 live births per year.

• Its incidence is higher in certain areas of Zimbabwe,Nigeria and South Africa.

Clinical Features

• Multiple frequent fractures

• Joint laxity

• Muscle weakness

• Curved bones

• Scoliosis

• Brittle teeth

• Short stature

• Blue sclera

• Triangular head,hearing loss &fragile skin

Classification

• OI has been classified in eight different types;

• TYPE 1

• Mild,autosomal dominent

• Divided in type 1A and 1B on the presence of dentinogenesis imperfecta

• Life expectancy is slightly reduced due to fatal fractures like basilar invagination

Type 2

• Severe and usually lethal in perinatal period

• Autosomal dominent

• Fetal death & death in first year of life

• Divided in types A,B &C subtypes on radilogical basis

Type 3

• Progressive & deforming

• Autosomal dominent

• Life span may be normal but with severe handicapping

Type 4

• Deforming with normal sclera

• Autosomal dominent

• Subtypes A & B on the presence of dentinogenesis imperfecta

Type 5

• Autosomal dominent

• Same features as type 4

• Different histologically ( bone appears mesh like)

• Calcification of radio ulnar interosseous membrane

Type 6

• Same features as type 4

• Autosomal dominent

• Different histologiclly ( fish scale like bone)

Types 7 & 8

• Discovered in 2006

• Autosomal recessive

• severe to lethel

Methods of testing

1. x-rays

• Osteopenia,multiple fractures and malunion

2. DNA sequencing using a collagen sample from blood

3. Biochemical testing using a collagen sample from skin

4.Testing during pregnency ultrasonography and amniocentesis

5.DXA scan

Treatment

• There is no cure for OI

• Aims of treatment

Increasing overall bone strength & density to prevent fractures & maintain mobility.

Non operative treatment

1. Biphosphonates are used to increase bone mass

2. Calcium and vitamin D

3. Phsiotherapy

4. Physical aids like cruthes,wheelchairs

Physical Therapy for OsteogenesisImperfecta

• Regardless of the type of treatment they receive, maintaining or improving muscle and bone strength are goals for all children with osteogenesis imperfecta.

• In addition to improving the quality of daily life, physicaltherapy is an especially important component of care following rodding surgery or other procedures resulting from fractures.

• As OI patients reach adolescence there tends to be a reduction in fractures, although the reason for this is

not yet clearly understood.

Operative treatment

1. Intramedullary rods

2. Osteotomies

3. Spinal fusion

Intramedullary Fixation

Historically, orthopedists used rods of a fixed length to help fractures heal and avoid or correct deformity. However, as the child grew, he or she was at risk for fracturing the leg immediately below the rod.

Fixed Length Rods

Fassier-Duval Telescopic Intramedullary System

Fassier-Duval rods are secured on the far end of each growth plate and telescope, or extend, as growth in the bone occurs. Following the initial placement, there is often no need for surgical adjustment while the child grows. The patient is therefore less likely to develop the type of fractures associated with older, non-telescoping rods, and may require fewer surgeries as well.

The development of the Fassier Duval nails have helped transform the nature of surgery, as these telescoping rods “grow” along with the child.

Fassier Duval Telescopic Rods

Looking to the Future of OsteogenesisImperfecta

• over the last ten years the prognosis for children with osteogenesis imperfecta has improved considerably,

• Taking the longer view, stem cell therapy and gene manipulation may eventually lead to dramatic advances in OI treatment.

• Lauren Davidson, a patient with osteogenesisimperfecta who went on to become a swimming medalist

OI & MEDIA

• (2000) The film Unbreakable features a character played by Samuel L. Jackson named Elijah Price who suffers from OI and is nicknamed "Mr. Glass" due to the brittleness of his bones.

• (2005) The movie Fragile features a child with this condition.

Thanks