Influence of test paradigm on loading dynamics during proximal femur fracture tests simulating sideways falls

Fall-related hip fractures are a serious public health issue in older adults. As most mechanistic hip fracture risk prediction models incorporate tissue tolerance, test methods that can accurately characterize the fracture force of the femur (and factors that influence it) are imperative. While bone...

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Bibliographic Details
Published in:Journal of the mechanical behavior of biomedical materials 2024-09, Vol.157, p.106631, Article 106631
Main Authors: Martel, Daniel R., Callaghan, Jack P., Mourtzakis, Marina, Willett, Thomas L., Laing, Andrew C.
Format: Article
Language:English
Subjects:
Accidental Falls
Aged
Aged, 80 and over
Biomechanical Phenomena
Bone biomechanics
Falls
Female
Femoral Fractures - physiopathology
Femur - physiology
Fracture force
Hip fracture
Humans
Impact
Loading rate
Male
Materials Testing
Mechanical Tests
Proximal Femoral Fractures
Stress, Mechanical
Weight-Bearing
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Summary:Fall-related hip fractures are a serious public health issue in older adults. As most mechanistic hip fracture risk prediction models incorporate tissue tolerance, test methods that can accurately characterize the fracture force of the femur (and factors that influence it) are imperative. While bone possesses viscoelastic properties, experimental characterization of rate-dependencies has been inconsistent in the whole-femur literature. The goal of this study was to investigate the influence of experimental paradigm on loading rate and fracture force (both means and variability) during mechanical tests simulating lateral fall loadings on the proximal femur. Six pairs of matched femurs were split randomly between two test paradigms: a ‘lower rate’ materials testing system (MTS) with a constant displacement rate of 60 mm/s, and a hip impact test system (HIT) comprised of a custom-built vertical drop tower utilizing an impact velocity of 4 m/s. The loading rate was 88-fold higher for the HIT (mean (SD) = 2465.49 (807.38) kN/s) compared to the MTS (27.78 (10.03) kN/s) paradigm. However, no difference in fracture force was observed between test paradigms (mean (SD) = 4096.4 (1272.6) N for HIT, and 3641.3 (1285.8) N for MTS). Within-paradigm variability was not significantly different across paradigms for either loading rate or fracture force (coefficients of variation ranging from 0.311 to 0.361). Within each test paradigm, significant positive relationships were observed between loading rate and fracture force (HIT adjusted R2 = 0.833, p = 0.007; MTS adjusted R2 = 0.983, p 
ISSN:1751-6161
1878-0180
1878-0180
DOI:10.1016/j.jmbbm.2024.106631