Zebra lines of pamidronate therapy in children

Background: Pamidronate therapy is increasingly used in children for the treatment of low bone mineral density and increased bone fragility resulting from a spectrum of conditions. The aim of the present study was to determine and describe the radiographic features associated with cyclical bisphosphonate therapy in the growing skeleton. Methods: A retrospective review of the radiographs of thirty-five children who had been managed with cyclical pamidronate was carried out. The physeal growth rates were estimated by measuring the band intervals on radiographs and the corresponding time intervals between the administered doses of pamidronate. Results: Metaphyseal bands, which we call zebra lines, were observed with band intervals that were dependent on the age of the patient, the rate of growth, and the dosing regimen. Epiphyseal and apophyseal bands were also observed in some patients. A distinction was made between Harris growth arrest lines and zebra lines. There was no evidence to suggest a deceleration in bone growth in children managed with pamidronate. Conclusions: The term zebra lines is proposed as a descriptive term for the characteristic pattern of metaphyseal banding seen on the radiographs of children receiving cyclical bisphosphonate therapy.