Osteogenesis Imperfecta

Key Features

• Rare genetic connective tissue disease;estimated incidence is 1 in 12,000–15,000

• Characterized by multiple and recurrent fractures

• There are several forms of osteogenesis imperfecta, designated type I to type XII

  • Types I–V are the result of autosomal dominant mutations

  • Types VI–XII are autosomal recessive

  • Each type is associated with a mutation of a different gene, varying levels of severity, and a range of characteristic features

• The severe fetal type (osteogenesis imperfecta congenita) is distinguished by multiple intrauterine or perinatal fractures

Clinical Findings and Diagnosis

• Characteristic findings

  • Blue sclerae

  • Thin skin

  • Hyperextensibility of ligaments

  • Otosclerosis with significant hearing loss

  • Hypoplastic and deformed teeth

• Clinical features lead to diagnosis in the majority of cases

• Moderately affected children have numerous fractures and exhibit dwarfism as a result of their acquired bone deformities and growth retardation

• Fractures begin to occur at different times and in variable patterns after the perinatal period, resulting in fewer fractures and deformities relative to severe cases

• Cortical thickness is reduced in the shafts of the long bones, and accessory skull bones that are completely surrounded by cranial sutures (wormian bones) are present in the skull

• Cardiovascular and respiratory problems are the most common causes of morbidity and mortality in adulthood

Treatment

• Surgical treatment involves deformity correction of the long bones

• Multiple intramedullary rods have been used to decrease the incidence of fractures and prevent deformity from fracture malunion

• Patients are often confined to wheelchairs during adulthood

• Bisphosphonates have been shown to decrease the incidence of fractures