ESPE Abstracts

Introduction: Vertebral fractures (VFs) are a common and severe finding in secondary and primary osteoporosis. VFs in patients with osteogenesis imperfecta (OI) are an important factor of morbidity and mortality and their presence serves as supportive evidence to initiate bisphosphonate (BP) therapy. In children, VFs have the potential to reshape and regain their original configuration. Vertebral reshaping is regarded a desired effect of BP therapy in children with OI who have sufficient remaining growth potential. Spontaneous vertebral body reshaping (i.e., medication-unassisted) has been reported in patients with secondary osteoporosis. To our best knowledge, spontaneous reshaping has not been reported in children with OI.

Case Report: This 17-year-old female had been diagnosed with OI type I aged 5 years (COL1A1 mutation) and had sustained more than 40 fractures. She had received regular physiotherapy but, due to parental reservations about medication, never received BP therapy or any other bone active medication. At the time of the first consultation, the patient had not sustained any fractures since age 15y, no back pain or other body pain. She had grown and matured normally. She had blue sclera but no dentinogenesis imperfecta and no skeletal deformity apart from a slight right-convex scoliosis. A lateral spine X-ray demonstrated transparent bones, with a mild anterior reduction in the height of vertebral bodies T6 and T7. A bone density scan demonstrated total BMD HAZ -2.1, subtotal BMC for Height -1.3, lumbar spine BMAD -1.1. Of great interest were previous spine X-rays taken at age 6 years at an external institution, which showed four VF at thoracic spine with moderate to severe deformities (Grade 2-3, modified Genant Semi-Quantitative Classification). Therefore, the two lateral spine x-rays, taken 11 years apart, demonstrate that substantial spontaneous vertebral reshaping had occurred during puberty.

Discussion: To date, vertebral reshaping in children with OI has been largely attributed to the effect of BP therapy in children who have sufficient remaining growth potential. This unusual case demonstrates that spontaneous reshaping of VF can also occur in BP-naïve OI patients. We hypothesize that natural growth plate activity of vertebrae, pubertal hormones, physiotherapy and avoidance of trauma may have contributed to the spontaneous reshaping in this case. Undoubtedly however, the persistent low bone mass predisposes this patient to future fractures