Which physical findings are characteristic of osteogenesis imperfecta (OI) type III?

Updated: Feb 24, 2020
  • Author: Manoj Ramachandran, MBBS, MRCS, FRCS; Chief Editor: Harris Gellman, MD  more...
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Of all types of OI, type III is the one that orthopedic surgeons see most often. Babies with type III OI are born with severe bone fragility and suffer multiple fractures at birth, though birth weight tends to be normal. The bone fragility may lead to joint hyperlaxity, muscle weakness, chronic unremitting bone pain, and skull deformities (eg, posterior flattening). In utero fractures are common.

The sclerae are bluish at birth but fade over the years, becoming white in adulthood. Dentinogenesis imperfecta is frequently seen. The presence of dentinogenesis imperfecta is independent of the severity of the OI. Patients may have a triangular face with frontal bossing. Malocclusion is common.

The chest and rib cage are usually spared, with few or no fractures of the ribs. Bowing of the limbs is common with growth, and multiple fractures may be seen later in life. The result is a short skeleton and a relatively less affected barrel-shaped chest, with a pectus carinatum deformity. Deformities of upper limbs may compromise function and mobility. Affected children tend to become wheelchair-bound and nonambulatory.

The classic radiographic appearance is that of popcorn bones, in which fractures of the physes in several locations result in several islands of endochondral ossification. With age, these ossifications tend to disappear, leaving an enlarged radiolucent epiphysis. The axial skeletal is also involved, with progressive platyspondyly and kyphoscoliosis. Eventually, the wide rib cage overlaps the narrow pelvis.

Basilar invagination is an uncommon but potentially fatal occurrence in OI. Vertigo is common in patients with severe OI. The incidence of congenital malformations of the heart in children with OI is probably similar to that in the healthy population. Hypercalciuria may be present in about 36% of patients with OI but does not appear to affect renal function. Constipation and hernias are also common in people with OI.

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