Effect of Femur Geometry on Hip Protectors Testing System

Abstract

There have been different types of simplified femoral geometry incorporated into test systems for testing the biomechanical effectiveness of hip protectors. However, the effect of the simplification of femoral geometry in simulated sideways impact experiment has not been reported. In this study, an actual femoral geometry was fabricated and examined along with a simplified femoral geometry in a surrogate hip arrangement to mimic the fracture-causing situation in a sideways fall. A pendulum impact testing machine was used to evaluate the impact force response of both the femoral geometries at various velocity and constant residual impact energy for both geometries. The result showed that the peak impact force varied only 9% between actual and simplified geometries after normalizing the weight for both femurs in testing without a hip protector. However, a higher distinction of the impact force responses of both femurs was observed when testing with a hip protector. This findings at this moment suggest that the femur geometry affects the performance of a testing system. Therefore, the simplified femur geometry may not accurately substitute for the actual femur geometry in comparison of the impact attenuation of a hip protector in a simulated sideways fall.