RESUMO
INTRODUCTION: Osteogenesis imperfecta (OI) is a genetic disorder caused by a mutation in the genes that encode the chains of type I collagen. Clinical manifestations include increased bone fragility and blue sclerae. OI type III is the most severe form with fractures occurring already in utero. Fracture immobilisation and orthopaedic surgery are the mainstay of treatment for patients with OI, and are combined with rehabilitation and bisphosphonate therapy. PATIENTS AND METHODS: The study involved 8 children with osteogenesis imperfecta type III, aged 1 month to 6 years. All of them were treated with cyclic intravenous infusions of pamidronate. Laboratory studies conducted before and after each 3-day cycle of pamidronate therapy included complete blood count, serum calcium, phosphorus, magnesium, osteocalcin, and calcium/creatinine index in morning urine and collagen type I cross-linked N-telopeptide (NTx). Infant total body densitometric scans were obtained in 5/8 patients. RESULTS: Patients were treated for periods of 3-58 months. Fracture rates decreased with treatment in all patients compared to the prenatal period. Pamidronate also slowed down bone turnover, and particularly the resorption rate. The most common side effects during treatment included hypocalcaemia (7/8 patients) and fever (up to 39 degrees C) after the first cycle of treatment. CONCLUSION: Symptomatic bisphosphonate therapy in children with osteogenesis imperfecta ameliorated the clinical course (decreased bone pain and reduced incidence of fractures). Pamidronate therapy had a positive impact on functional parameters such as independence in everyday activities and better mobility. The treatment was safe.