Growth of infants with osteogenesis imperfecta treated with bisphosphonate

Osteogenesis imperfecta (OI) is a heritable bone disease characterized by bone brittleness and various degrees of growth disorder. Cyclic pamidronate therapy is reportedly useful to prevent bone fracture in OI and in infants with OI, but, it remains unclear how infants with OI grow during bisphosphonate therapy. Height and weight measurements of OI infants treated with cyclic pamidronate therapy were taken before and every 6 months during therapy until 18 months. Vertebral morphometry and the concavity index were analyzed using X-ray films taken simultaneously. Among OI patients, those in the group for which the height z-score decreased tended to have more femur fractures than those of the group for which the height z-score increased. Morphometry of the lumbar spine showed that compression fractures occurred less during cyclic pamidronate therapy, by which the lumbar bone mineral density increased. Bisphosphonate preserved vertebral morphometry during 18 months after starting therapy in infants. Prevention of femur fracture during the infantile period might help prevent short stature; therapeutic strategies during infancy must better emphasize prevention of long bone fracture before the beginning of gait.