An improved understanding of the mechanical properties of human femurs is a milestone towards a more accurate assessment of fracture risk. Digital image correlation (DIC) has recently been adopted to provide full-field strain measurements during mechanical testing of femurs. However, it has typically been used to measure strains on the anterior side of the femur, whereas in both single-leg-stance and sideways fall loading conditions, the highest deformations result on the medial and lateral sides of the femoral neck. The goal of this study was to measure full-field deformations simultaneously on the medial and lateral side of the femoral neck in a configuration resembling a fall to the side. Twelve female cadaver femurs were prepared for DIC measurements and tested in sideways fall at 5 mm/s displacement rate. Two pairs of cameras recorded the medial and lateral side of the femoral neck, and deformations were calculated using DIC. The samples exhibited a two-stage failure: first, a compressive collapse on the superolateral side of the femoral neck in conjunction with peak force, followed by complete femoral neck fracture at the force drop following the post-elastic phase. DIC measurements corroborated this observation by reporting no tensile strains above yield limit for the medial side of the neck up to peak force. DIC measurements registered onto the bone micro-architecture showed strain localizations in proximity of cortical pores due to, for instance, blood vessels. This could explain previously reported discrepancies between simulations and experiments in regions rich with large pores, like the superolateral femoral neck.

对人股骨力学性能的更好理解是朝着更准确评估骨折风险的里程碑。最近已采用数字图像相关（DIC）技术在股骨力学测试过程中提供全场应变测量。但是，它通常用于测量股骨前侧的应变，而在单腿姿势和侧向跌落载荷条件下，股骨颈内侧和外侧的变形最大。这项研究的目的是同时测量股骨颈内侧和外侧的全视野变形，其形状类似于侧面跌落。准备十二只女性尸体股骨用于DIC测量，并以5 mm / s的位移速率侧向跌落进行测试。两对照相机记录了股骨颈的内侧和外侧，并使用DIC计算了变形。样品表现出两个阶段的破坏：首先，在股骨颈的上外侧发生压缩性塌陷并伴有峰值力，然后在弹性后阶段的力下降处股骨颈完全断裂。DIC测量通过报告在直至最大力的情况下，颈部内侧没有超过屈服极限的拉伸应变，证实了这一观察结果。记录在骨骼微结构上的DIC测量结果显示，由于血管等原因，应变在皮质孔附近定位。这可以解释先前报道的模拟和实验之间的差异，该差异在具有大孔的区域（如股外侧颈）中出现。