ESPE Abstracts

Introduction: Osteogenesis Imperfecta (OI) is a group of rare hereditary collagen disorders. Vertebral compression fractures and vertebral deformities are well-known complications of OI. Intravenous zoledronic acid is widely used to improve the bone mineral density in children with OI. This study aimed at assessment of the changes in vertebral compression and shape in children who received regular zoledronic acid infusions.

Methods: This was a prospective study that ran over approximately 5 years recruiting infants, children and adolescents with OI attending the Paediatrics Endocrinology Clinic of Ain Shams University (PECASU). It included 23 patients with OI who completed the required follow up. All participants had full history taken and detailed examination including anthropometric measurements and laboratory assessment. Clinical follow up and zoledronic acid infusions were done at 3 monthly intervals for those < 3 years and at 6 monthly intervals for older children. All patients were prescribed the recommended daily doses of calcium and vitamin D. Lateral X-rays of the thoracic and lumbar spine were done for each patient at initial enrolment then each year till they reached the minimum X-ray score then no further X-rays were done. The Score of Spine Morphology (SSM) by Koerber et al., 2012 was used to assess the effect of Zoledronic acid infusions on thoracolumbar spine morphology. The SSM relied on three criteria: vertebral compression, thoracolumbar kyphosis and deformity type to formulate a severity classification which was then used to develop a severity score.

Results: The mean age of the included patients was 5.3 ± 0.9 years, their length/height SDS was -3.42±0.61 and their BMI SDS was -0.82±0.46 at inclusion in the study. The severity score showed significant improvement across the follow up period (P = 0.001). The maximum and average point values for spine compression showed significant improvements with treatment (P = 0.026 and P = 0.008 respectively). However, the angle of kyphosis on lateral thoracolumbar spine X-ray showed no significant difference (0.067). The maximum and average point values for spine deformity showed non significant results (P = 0.252 and P = 0.054 respectively).

Conclusion: Regular Zoledronic acid infusions in children with OI improved the severity score of spine morphology without significant adverse effects or electrolyte disturbances. Zoledronic acid infusions were associated with a significant reduction in vertebral compression with less remarkable effects on vertebral shapes and the angle of kyphosis.