Bone Abstracts

Objective: Osteogenesis imperfecta is characterized by hereditary skeletal fragility. Bisphosphonates are the first line medical treatment in moderate and severe OI types III/IV. There is no consensus regarding treatment beginning and treatment regimen in the first years. Objective of the presented project was the evaluation of the therapeutic effect of 1 year of bisphosphonate treatment (BP; neridronate i.v. 2 mg/kg body weight every 3 months) on vertebral shape and mobility in children with severe OI.

Methods: Matched pair analysis of 12 children with OI depending on time of initiation of bisphosphonate treatment (early starters 0–3 months; late starters 3–5 months). Areal Bone mineral density (BMD) of the lumbar spine (L2-L4) was assessed via DXA (GE Lunar iDXA). Vertebral shape was assessed by x-ray of the lateral spine (Morphometry score ‘Körber’). Mobility was analysed by age when children reached motor milestones.

Results: Early starters (n=6, 4 females; OI type III n=4; OI IV n=2; age at start of BP treatment 0.65±0.35 months) and late starters (n=6; 3 females; OI type III n=3; OI IV n=3; age at start of BP 3.8±1.7 months) presented with a reduced mean lumbar BMD at start of treatment and after one year (early starters: 0.230 g/cm² vs 0.244 g/cm²; late starters 0.131 g/cm² vs 0.236 g/cm²). Vertebral morphometry score changed from 1 to 24.8 and from 57.25 to 53.8 demonstrating a much more severely affected spine in the late starters. Motor function assessment revealed ‘pulling to stand‘ with 13.6 months vs 15.0 months and ‘first supported steps’ with 17.0 vs 22.5 months.

Conclusion: Patients starting during the newborn period with i.v. neridronate treatment showed less deterioration of vertebral shape and tended to have a better motor function development than children starting at the mean age of 3.8 months. Therefore one can assume that an early antiresorptive treatment might be beneficial for the development of the affected children. Further trials are needed to outweigh risk and benefit especially regarding the long term course of the patients.

Disclosure: The authors declared no competing interests.