Abstract：
Hip fracture accounts for a large number of hospitalizations, thereby causing substantial economic burden. Majority (> 90%) of all hip fractures are associated to sideways fall. Studies on sideways fall usually involve loading at quasi-static or at constant displacement rate, which neglects the physics of actual fall. Understanding femur resonance frequency and associated mode shapes excited by dynamic loads is also critical. Two commercial extramedullary implants, proximal femoral locking plate (PFLP) and variable angle dynamic hip screw (VA-DHS), were chosen to carry out the preclinical assessments on a simulated Evans-I type intertrochanteric fracture. In this study, we hypothesized that the behavior of the implant depends on the loading types-axial static and transverse impact-and a rigid implanted construct will absorb less impact energy for sideways fall. The in silico models were validated using experimental measurements of full-field strain data obtained from a 2D digital image correlation (DIC) study. Under peak axial load of 3 kN, PFLP construct predicted greater axial stiffness (1.07 kN/mm) as opposed to VA-DHS (0.85 kN/mm), although the former predicted slightly higher proximal stress shielding. Further, with greater mode 2 frequency, PFLP predicted improved performance in resisting bending due to sideways fall as compared to the other implant. Overall, the PFLP implanted femur predicted the least propensity to adverse stress intensities, suggesting better structural rigidity and higher capacity in protecting the fractured femur against fall.
摘要：
髋部骨折导致大量住院，造成了巨大的经济负担。大多数（>90%）的髋部骨折与侧身跌倒有关。对侧向坠落的研究通常涉及准静态或恒定位移速率的载荷，忽略了实际跌倒的物理学。了解股骨共振频率和动态载荷激发的相关模式形状也很关键。两种商业髓外植入物，股骨近端锁定钢板（PFLP）和可变角度动力髋螺钉（VA-DHS），选择对模拟的Evans-I型股骨粗隆间骨折进行临床前评估。在这项研究中,我们假设植入物的行为取决于负载类型-轴向静态和横向冲击-刚性植入结构将吸收较少的冲击能量侧向下降。使用从2D数字图像相关（DIC）研究获得的全场应变数据的实验测量结果验证了计算机模型。在3kN的峰值轴向载荷下，PFLP结构预测更大的轴向刚度（1.07kN/mm），而不是VA-DHS（0.85kN/mm），尽管前者预测近端应力屏蔽稍高。Further,具有更大的模式2频率，PFLP预测，与其他植入物相比，在抵抗侧向跌落引起的弯曲方面的性能有所提高。总的来说,PFLP植入股骨预测不良应力强度的倾向最小，提示更好的结构刚度和更高的保护股骨骨折防止跌倒的能力。
