Radiological Features of Zoledronic Acid Therapy in Saudi Children with Osteogenesis Imperfecta

Abstract

Background: The majority of osteogenesis imperfecta (OI) cases have an autosomal dominant pattern of inheritance and are usually caused by mutations in genes encoding type I collagen. Patients with OI may have blue sclerae, dentinogenesis imperfecta, and growth deficiency. Zoledronic acid is a third-generation bisphosphonate which was reported to inhibit osteoclast-mediated bone resorption, improve bone density, and reduce incidence of fractures. Aim: To describe the radiographic features of cyclic Zoledronic acid administration on the growing skeleton in children with OI and to report the efficacy of Zoledronic acid on bone mineral density. Methods: We retrospectively reviewed the radiographs of 11 children treated with Zoledronic acid. The age of these children ranged from one to 13 years. Zoledronic acid was administrated intravenously at 6 months intervals at the Pediatric Endocrinology Day Medical Unit, King Faisal Specialist Hospital and Research Centre, and Security Forces Hospital, Riyadh, Kingdom of Saudi Arabia for 2 years. Results: During the course of treatment, a gradual increase in bone density was observed. The baseline mean lumbar BMDz score was -4.9SD + 1.3, which improved to a mean score of -2.7SD + 1.1, and a mean whole body BMDz score was -2SD +1.2 and improved to a mean score of -1.1SD + 1.3 by the end of therapy. Post treatment, there were multiple sclerotic metaphyseal bands seen in all children in the long bones paralleling to the growth plates and corresponding to the number of treatment cycles. Conclusion: Intravenous Zoledronic acid in children with osteogenesis imperfecta improved the bone mineral density and resulted in permanent sclerotic metaphyseal bands.