Osteogenesis imperfecta: radiological view on the pediatric patient

Osteogenesis imperfecta (OI) is a genetically and clinically heterogeneous disorder of bone and connective tissue characterized by osteoporosis, fragile bones, hyperextensible joints, dentinogenesis imperfecta, bluish coloration of the sclerae, and adult-onset hearing loss. Detailed medical history, careful physical examination, radiographic features of fractures, and biochemical analysis of skin collagen are the four cornerstones of accurate diagnosis. A radiology specialist should be aware of subtle changes seen on radiographs as well as of specific osteogenesis features (i.e. „popcorn” calcifications) and difficult differential diagnosis (i.e. hypertrophic callus formation versus osteosarcoma; child abuse fractures versus true osteogenesis imperfecta). About 300 different mutations have been identified within COL1A1 and COL1A2 genes that encode the chains of type I collagen. Depending on the location of the mutation within the collagen gene, these produce a variety of clinical pictures which range from mild OI type I, lethal OI type II to severely deforming OI type III and mildly deforming OI type IV, OI type V is moderate in severity and it is similar to OI type IV, OI type VI is extremely rare and two recessive types of OI, types VII and VIII, were identified in 2006. Each of the eight types has a common radiologic appearance that helps in establishing the diagnosis. The purpose of this article is to give an as comprehensive as possible review of the radiological picture of OI in pediatric patients. Special emphasis will be given to specific radiological prognostic features as well as to the differential diagnosis.

KEY WORDS:
osteogenesis imperfecta, dentinogenesis imperfecta, fracture, blue sclerae, collagen