Osteoporosis imperfecta (OI) is a genetic disorder characterized by fragility of bone, deafness, blue sclerae; and laxity of joints. Four types of OI are distinguished by clinical findings. Although mutations affecting collagen I are responsible for the disease in the most patients, the mechanism by which the genetic defects cause abnormal bone development has not been well established. Therefore we evaluated static and dynamic bone histomorphometry of type I OI in the case study of a 15 year old boy with OI who had blue sclerae, a history of frequent fracture and a familial history of blue sclerae. Biopsy of the ilium showed loss of connection between the cortical bone and trabecular bones. The Harversian system in the cortical bone was poorly developed. In the trabecular bones, the lamellar pattern was poorly developed. Mineral apposition rate of the cortical bone was 1.0 m/day and of the trabecular bone was 0.79 m/day. Thus OI might be regard as a disease whereby abnormal collagen synthesis interferes with bone strength by multiple mechanisms.
Adolescent ; Biopsy ; Bone Development ; Collagen ; Deafness ; Humans ; Ilium ; Joints ; Male ; Osteogenesis Imperfecta* ; Osteogenesis* ; Osteoporosis ; Sclera