Beneficial effects of intravenous pamidronate treatment in children with osteogenesis imperfecta under 24 months of age.

Osteogenesis imperfecta (OI) is an inherited disorder characterized by bone fragility and low bone mass. Low bone density and fracture is a cause of morbidity. Limited data exists on bisphosphonate treatment in patients under 24 months of age. The objective of the study was to examine the safety and efficacy of pamidronate in children under 24 months with OI. To do so, we carried out a retrospective chart review and analysis of OI patients started on intravenous pamidronate under 24 months of age. Pamidronate was administered in three-day cycles. Growth, the number of fractures, and lumbar bone mineral densities were recorded both prior to and after treatment initiation. A total of 18 patients were reviewed. Five were classified as OI type I, seven were type III, and six were type IV. The mean age at treatment initiation was 12 months (range 11 days to 23 months). The mean lumbar z score at baseline was -3.63, which improved to -1.53 at one year (P < 0.01) and 0.79 (P < 0.01) at the end of the study. The fracture rate improved from 68 fractures in 209 months (0.32 fractures/patient-month) before treatment to 41 fractures in 1,248 months (0.03 fractures/patient-month) post-treatment (P < 0.05). Height standard deviation score (SDS) was conserved from baseline to end of study (-2.12 ± 2.45 vs. -2.45 ± 2.73) (P = 0.05) with an average follow-up of 73 months. The only adverse effect recorded in six infants was fever during the initial pamidronate infusion. Treatment with intravenous pamidronate is safe, significantly improves lumbar bone mineral density (L-BMD), and reduces fracture rates in young infants with OI while preserving linear growth.