About osteogenesis imperfecta
Osteogenesis imperfecta is an inherited condition characterized by
the fragility of the skeletal system and a susceptibility to fractures
of the long bones or vertebral compressions. Osteogenesis imperfecta
(OI) also called as brittle bone disease is the most common genetic
cause of osteoporosis.
Osteogenesis imperfecta: Incidence, age and sex
Osteogenesis imperfecta is an autosomal dominant disorder that occurs
in all racial and ethnic groups. The incidence of OI that is
detectable in infancy is about 1 / 20, 000.
Signs and symptoms of osteogenesis imperfecta: Diagnosis
Osteogenesis imperfecta has the triad of fragile bones, blue sclerae
and early deafness. There are four types based on clinical and
radiographic criteria. Other connective tissue abnormalities include
easy bruising, joint laxity and mild short stature compared with family
members. Fractures result from mild to moderate trauma and decrease
after puberty. In type II (Perinatal /Lethal) the infants may be
stillborn or die in the 1st year of life due to extreme fragility of the
skeleton and other connective tissue. Type III (Progressive
Deforming) is the most severe nonlethal form of osteogenesis imperfecta
and results in significant physical disability. Virtually all type III
patients have scoliosis and vertebral compression. Type IV (Moderately
Severe) patients present at birth with in-utero fractures or bowing of
lower long bones. They may also present with recurrent fractures after
ambulation. Severe osteogenesis imperfecta can be detected prenatally
by ultrasonography as early as 15 weeks of
gestation. In the neonatal period, the normal to elevated alkaline
phosphatase levels present in OI distinguishes it from hypophosphatasia.
Causes and prevention of osteogenesis imperfecta
A genetic mutation results in structural or quantitative defects in
type I collagen. Classical osteogenesis imperfecta is an autosomal
dominant disorder. Some familial ocurrences of osteogenesis imperfecta
are caused by parental mosaicism for dominant collagen mutations.
Osteogenesis imperfecta: Complications
The morbidity and mortality of OI are due to cardiopulmonary
complications. Recurrent pneumonias and declining pulmonary function
occur in childhood and cor pulmonale is seen in adults. Neurologic
complications include basilar invagination, brainstem compression,
hydrocephalus, and syringohydromyelia.
Osteogenesis imperfecta: Treatment
There is no cure for osteogenesis imperfecta. For severe non-lethal
osteogenesis imperfecta active physical rehabilitation in the early
years, allows children to attain a higher functional level than does
orthopedic management alone.
Long leg plastic braces, gait aids and a programme of swimming and
conditioning helps to improve quality of life. Severely affected
individuals require a wheelchair for community mobility but can acquire
self-care skills. Teens with osteogenesis imperfecta may require
psychological support with body image issues.
Orthopedic management of osteogenesis imperfecta is aimed at fracture
management and correction of deformity to enable function. Growth
hormone improves bone histology in growth hormone-responsive children. A
short course of treatment of children with osteogenesis imperfecta with
bisphosphonates (IV pamidronate or oral olpadronate) confers some