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IN-VITRO STRAIN DISTRIBUTION DURING SIDEWAYS FALL IN THE PROXIMAL HUMAN FEMUR
Presentation 1499 − Topic 26. Injury biomechanics
S351
IN-VITRO STRAIN DISTRIBUTION DURING SIDEWAYS FALL IN THE PROXIMAL HUMAN FEMUR Lorenzo Zani (1), Luca Cristofolini (1,2), Mateusz Juszczyk (1,2), Marco Viceconti (1,3)
1. Medical Technology Lab, Rizzoli Orthopaedic Institute; 2. Engineering Faculty, Univ. of Bologna, Italy; 3. Dept. Mechanical Engineering, Univ. of Sheffield, UK
Introduction
Results and Discussion
There is a significant interest about failure process leading to hip fractures in sideways falls. Previous works have focused on determining failure load and how the crack starts and propagates during the fracture process [de Bakker,2009]. The scope of this work was to provide a better understanding of the strain distribution, and of its correlation, exploring a wide range of loading direction.
Consistently with previuos studies [de Bakker, 2009; Lotz, 1995], the largest compressive strain was observed on the superior lateral region of the neck: 1712±379 microstrain, while the largest tensile strain was observed in the medial region: 907±229 microstrain. Furthermore, compressive strains were generally found to be more than two times the tensile ones (Fig.2). Increasing the adduction angle all strains increased in terms of magnitude. Increasing the internal rotation only the principal compression strains increased. Conversely, a minimum was found at 15° for tensile strains probably due to the compensation of the antero-version of the neck. In conclusion, this study confirms that during sideways fall the supero-lateral region of the neck is most stressed and is possibly the failure initiation site.
Methods Ten cadaver femurs were instrumented with 16 strain rosettes at four levels (head, neck, lesser trochanter, diaphysis) for each side (anterior, posterior, medial, lateral). Since sideway fall is an unpredictable event, a wide cone of loading direction was explored for a total of twelve loading configurations, as a combination of three values for the internal rotation (0°, 15°, 30°) and four values for the adduction (0°, 10°, 20°, 30°) using a validated experimental setup [Zani,2010] (Fig. 1).
References. de Bakker et al, J Biomech, 42: 1917–1925, 2009. Zani et al, 17th ESB Congress, Abstract 0526, 2010. Lotz et al, Osteoporos Int., 5: 252–261, 1995 Acknowledgements: EC grant “Osteoporotic Virtual Physiological Human, VPHOP” (FP7ICT2008-223865).
Fig. 1: In-vitro setup used to explore a range of loading directions during sideways fall.
Fig. 2: Tensile strain was found on the medial side. Compressive strain was found on the lateral side (in the plots this is reported in absolute value). ESB2012: 18th Congress of the European Society of Biomechanics
Journal of Biomechanics 45(S1)
S351
IN-VITRO STRAIN DISTRIBUTION DURING SIDEWAYS FALL IN THE PROXIMAL HUMAN FEMUR Lorenzo Zani (1), Luca Cristofolini (1,2), Mateusz Juszczyk (1,2), Marco Viceconti (1,3)
1. Medical Technology Lab, Rizzoli Orthopaedic Institute; 2. Engineering Faculty, Univ. of Bologna, Italy; 3. Dept. Mechanical Engineering, Univ. of Sheffield, UK
Introduction
Results and Discussion
There is a significant interest about failure process leading to hip fractures in sideways falls. Previous works have focused on determining failure load and how the crack starts and propagates during the fracture process [de Bakker,2009]. The scope of this work was to provide a better understanding of the strain distribution, and of its correlation, exploring a wide range of loading direction.
Consistently with previuos studies [de Bakker, 2009; Lotz, 1995], the largest compressive strain was observed on the superior lateral region of the neck: 1712±379 microstrain, while the largest tensile strain was observed in the medial region: 907±229 microstrain. Furthermore, compressive strains were generally found to be more than two times the tensile ones (Fig.2). Increasing the adduction angle all strains increased in terms of magnitude. Increasing the internal rotation only the principal compression strains increased. Conversely, a minimum was found at 15° for tensile strains probably due to the compensation of the antero-version of the neck. In conclusion, this study confirms that during sideways fall the supero-lateral region of the neck is most stressed and is possibly the failure initiation site.
Methods Ten cadaver femurs were instrumented with 16 strain rosettes at four levels (head, neck, lesser trochanter, diaphysis) for each side (anterior, posterior, medial, lateral). Since sideway fall is an unpredictable event, a wide cone of loading direction was explored for a total of twelve loading configurations, as a combination of three values for the internal rotation (0°, 15°, 30°) and four values for the adduction (0°, 10°, 20°, 30°) using a validated experimental setup [Zani,2010] (Fig. 1).
References. de Bakker et al, J Biomech, 42: 1917–1925, 2009. Zani et al, 17th ESB Congress, Abstract 0526, 2010. Lotz et al, Osteoporos Int., 5: 252–261, 1995 Acknowledgements: EC grant “Osteoporotic Virtual Physiological Human, VPHOP” (FP7ICT2008-223865).
Fig. 1: In-vitro setup used to explore a range of loading directions during sideways fall.
Fig. 2: Tensile strain was found on the medial side. Compressive strain was found on the lateral side (in the plots this is reported in absolute value). ESB2012: 18th Congress of the European Society of Biomechanics
Journal of Biomechanics 45(S1)