Radiographic long bone appearance in a child administered cyclical pamidronate

The appearance of this radiograph caused considerable concern in the casualty department. It shows the left wrist of an 11 year old girl and was taken following suspicion of a fracture. She had been treated for two years with cyclical pamidronate for type 1 osteogenesis imperfecta (OI). There are multiple linear areas of increased bone density at the metaphysis of the distal radius and ulnar, thickened cortices, with evidence of background osteopenia and no fracture. It is likely that the areas of increased bone density correspond to the timings of the pamidronate infusions.The use of pamidronate for childhood OI has increased because of its proven benefits of increased bone density, reduced fracture rates, and improved bone pain.1,2 For the first time the effects of pamidronate on bone tissue in growing children have been elucidated from bone histomorphometric studies, thus aiding the explanation for the radiographic appearance.3 Treatment leads to a marked reduction in bone remodelling activity of trabecular bone which is predominantly found in the metaphysis of long bones. The lines of increased bone density are likely to be the result of an increase in both the number of trabeculae and the amount of residual calcified cartilage within the secondary spongiosa. The thickened cortices result from preserved modelling directed bone formation coupled with inhibition of bone resorption.3Children with OI are likely to present to the casualty department. This radiograph shows the appearance that might be expected in such individuals treated with pamidronate, and does not require further investigation