Musculoskeletal Functional Outcomes in Children with Osteogenesis Imperfecta: Associations with Disease Severity and Pamidronate Therapy

Background: Intravenous pamidronate has been used off-label in the treatment of severe osteogenesis imperfecta (OI) for almost 20 years. Previous studies have found correlations between function and bone density in patients with OI, but have not studied the functional outcomes of these patients after bisphosphonate therapy with a validated outcome measure. The goal of this investigation is to describe the functionality and comfort of children with OI. We hypothesize that function is impaired in children with severe OI as measured using the Pediatric Outcomes Data Collection Instrument (PODCI) and that improvements in the function of children with severe OI may be observed in association with intravenous bisphosphonate therapy.

Methods: A total of 25 patients with OI were evaluated, of those, 15 received pamidronate therapy. Children with >2 long bone fractures per year were classified as having severe OI and were eligible for pamidronate therapy. Functional evaluation was performed using the PODCI for children who qualified for pamidronate therapy (severe OI) and those who did not qualify for pamidronate therapy (mild OI). PODCI evaluation was also performed after treatment with pamidronate in the group that qualified for pamidronate therapy.

Results: There was a statistically significant difference at baseline between patients with "mild" and "severe" OI in the sports/physical functioning scale (P=0.0032). Among the children who received bisphosphonate therapy, PODCI scores in the sports/physical functioning domain were significantly improved after pamidronate therapy (P=0.0364).

Conclusions: This study indicates that children with mild forms of OI can be differentiated from their more severe counterparts by their ability to participate in high-level play activities. Furthermore, patients with "severe" OI show a significant improvement in their ability to participate in high-level play after 1 year of pamidronate.

Level Of Evidence: Level IV.