Rapid increase in grip force after start of pamidronate therapy in children and adolescents with severe osteogenesis imperfecta.

OBJECTIVE To examine changes in grip force during pamidronate therapy in children and adolescents with severe osteogenesis imperfecta (OI). METHODS Maximal isometric grip force of the nondominant hand was prospectively determined in 42 patients (age at the start of the study: 7.3-15.9 years; 18 girls) with severe forms of OI. Patients were treated with intravenous pamidronate infusions given in 4 monthly cycles, each cycle consisting of 3 infusions (1 mg pamidronate/kg body wt) on 3 successive days. RESULTS At the start of pamidronate therapy, grip force was low compared with age-specific reference data (age z score mean +/- standard deviation: -2.7 +/- 2.1) but was normal for weight (weight z score: -0.1 +/- 1.8). Four months after the first pamidronate infusion cycle, grip force had increased significantly, whether related to age (age z score: -2.0 +/- 1.8) or to weight (weight z score: 0.6 +/- 1.5). At 2 years after the start of therapy, grip force z scores were not significantly different from the 4-month results. CONCLUSIONS Maximal isometric grip force markedly increases after a single cycle of intravenous pamidronate in children with severe forms of OI, and this gain in grip force is maintained for at least 2 years.