Bone Abstracts

Background: Osteogenesis imperfecta (OI) is a clinically heterogenous heritable connective tissue disorder with increased bone fragility. Intravenous bisphosphonate therapy is the most widely used medical approach. This treatment leads to an increase of the bone mineral density and reduces the fracture rate.

Presenting problem: We present our experience with five OI patients (one female, four males) between 2005 and 2016 who had bone fractures either in utero or in their first month of life. Targeted genetic testing identified causative mutation in 4/5 patients, three in COL1A2 and one in COL1A1 gene. Children have been treated with cyclic intravenous pamidronate, the mean age of treatment initiation was 6.6 weeks.

Clinical management: Children were clinically defined as OI type IV (patient 1), OI type I (patient 2), and OI type III (patients 3, 4, 5). Moderate side effects of pamidronate were observed only during the first infusion - temporary granulocytopenia was documented in patient 1; flu-like reaction with fever in patients 3 and 5. Treatment for 30.6 months on average reduced the rate of fractures and improved mobility of patients. Lumbar spine areal bone mineral density showed a rapid increase. Repeated intramedullary roding surgery has been performed in patient 1 and 3. The patients 2 and 3 developed pectus excavatum. All children are short for age (−3.48±1.78 S.D.). The patient 1 is able to walk short distances with aids, the patients 2, 3, 4, 5 are able to walk short distances independently. All patients show normal mental development.

Discussion: Mutations in genes COL1A1 and COL1A2 are mostly inherited through an autosomal dominant pattern. They could be associated with moderate to severe phenotype OI – type I, II, III, and IV. Bone fractures and deformities documented before or early after birth call for an urgent intervention. Early treatment with intravenous pamidronate seems to be safe and efficient. Only moderate side effects were observed. Most of the patients show very good mobility in spite of their severe perinatal status. Early pharmacotherapy, long-lasting rehabilitation, and corrective surgery significantly improve quality of life in children with a manifestation of multiple OI fractures immediately after birth.

Disclosure: The authors declared no competing interests.