Loading Effects: Geometry versus Intrinsic Forces in Injury Risk Assessment of the Femur in Children with Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is a rare genetic disorder but is the most common disorder of bone etiology with little known about the impact of physiologic factors on fracture risk. Finite element analysis (FE) models of OI bone have been previously developed to examine fracture risk during ambulation and various daily activities of the femur and tibia. This study aims to further investigate the impact of long bone deformity and muscle activation forces in children and adolescents with OI. Pediatric femoral FE models of normal, OI type I, and OI type III bone material properties assessed effects of lateral bowing versus increased gluteus medius and gluteus maximus force production on bone injury risk. Models incorporating increased lateral bowing and muscle forces showed up to 7.56% higher stress levels than the standard model with no bowing and normal muscle forces, with muscle forces having a greater impact than lateral bowing. This study provides quantitative information to help establish methodology for FE analysis to assess femoral fracture risk in individuals with OI.