Experimental Validation of Subject-Specific Dynamics Model for Predicting Impact Force in Sideways Fall

Masoud Nasiri Sarvi,Jun Ouyang,Yunhua Luo,Peidong Sun

doi:10.4236/jbise.2014.77043

Abstract

Sideways fall has been identified as the most critical situation for the elderly to develop hip fractures. The impact force onto the greater trochanter is the key factor for predicting fracture risk. For the elderly, the impact force can only be determined by dynamics simulations, and the dynamics model must be first validated by experiments before it can be applied in clinic. In this study, subject-specific whole-body dynamics models constructed from dual energy X-ray absorptiometry (DXA) images of the subjects were validated by controlled and protected fall tests using young volunteers. The validation results suggested that subject-specific dynamics model is much more accurate in predicting impact force induced in sideways fall than conventional non-subject-specific dynamics model. Therefore, subject-specific dynamics model can be applied in clinic to improve the accuracy of assessing hip fracture risk.

Highlights

Statistical studies show that more than 90% of hip fractures are caused by falls [1] [2]
A two-degree-of-freedom dynamics model was constructed by Kim using parameters obtained by system identification techniques [11]
Anthropometric and dynamics parameters of body segments are extracted from a whole body dual energy X-ray absorptiometry (DXA) image of the subject and used in constructing a subject-specific whole-body dynamics model

Summary

Introduction

Statistical studies show that more than 90% of hip fractures are caused by falls [1] [2]. Van den Kroonenberg proposed a three-link dynamic model for studying sideways fall from standing height [9]. Laing and his colleagues attempted to identify hip stiffness by studying experimentally obtained force-deflection relation of the pelvis affected by a lateral impact to the hip [10]. Groen studied the effects of hand arrest, impact velocity and trunk orientation on hip impact force [14]. Zijden and his co-workers investigated the effectiveness of fall techniques in reducing impact force induced in sideways fall [15]

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Conclusion