Assessment of Bone Density in Osteogenesis Imperfecta in Pediatric and Adolescent Age Group: Can the Metacarpal Index Play a Role?

Abstract

Osteogenesis Imperfecta (OI), an inherited genetic disorder affecting 1 in 20,000 people worldwide, is currently treated with bisphosphonates for moderate and severe forms. Dual-energy X-ray absorptiometry (DXA) is the standard method for assessing the improvement in bone quality in OI but due to the unavailability of DXA in some places, hand radiographs can be used to calculate the second metacarpal index (MCI) to assess the bone quality in many osteoporotic disorders. In this study we evaluated the feasibility of using metacarpal index to assess the bone quality in OI in children. We evaluated the MCI values in 37 children aged 1-18 years at baseline (before intervention), and following pamidronate treatment in 18 children with type III or type IV OI. A decrease in MCI was noted with ageing as anticipated in the OI population, and we also observed an increase in MCI among the younger cohort (under 8 years) receiving pamidronate compared to the older cohort (above 8 years). The change in MCI after pamidronate therapy was monitored, and those who were initiated on pamidronate at a younger age showed more improvement in MCI than those who were started at a later age. Our study suggests that when DXA measurements are not feasible, MCI can be a potential tool to assess bone quality and evaluate bisphosphonate therapy in the OI population.