Changes in apatite crystal size in bones of patients with osteogenesis imperfecta.

Apatite crystal size in compact bone of children (age less than 11 years) and adolescents (age greater than 12 years) with osteogenesis imperfecta (OI) was analyzed by X-ray diffraction. Eight type I, 4 type II, 11 type III, and 14 type IV OI patients were studied along with 9 controls. The crystal size was most significantly reduced in type II patients, all of whom had died at birth. Crystal size was also diminished in both children and adolescents with types III and IV, whereas with type I OI, crystal size was reduced in children only, returning to normal in adolescence. There was a trend toward increased bone crystal size with age in both OI patients and controls.