Biomechanical load sharing in the foot during dynamic, load-bearing activity

脚在结构上是多余的。它不像大腿或小腿，那里只有一到两块大骨头，生物力学负荷只有一种传递方式。相反，脚是一个由26块骨头组成的复杂结构，每块骨头都承受着生物力学的负荷。一个有趣的事实是，大约四分之一的骨头在整个人体的两个脚。这使得足部在身体和地面之间传递负荷时具有极大的灵活性。但人们对脚是如何做到这一点的却知之甚少。连接踝关节和地面的是五根骨头，从脚跟（跟骨）开始，到每个脚趾终止。第一根射线也被称为内侧纵弓，第五根射线是外侧纵弓。每条射线将一部分生物力学总载荷从人体传递到地面。但由于足部的结构冗余，无法确定地计算出每根射线承受的总载荷的比例。每条射线有多少负荷，负荷分担是否总是相同的，负荷分担是否每一步都在变化，负荷分担是否在每一步都在变化，负荷分担是否在不同的人之间是相同的，这些问题仍然是一个悬而未决的问题。本研究计划探讨足部负荷分担的问题。它使用两种互补的方法，直接测量健康的测试对象执行动态任务和足部解剖，鞋类和矫形器的有限元（FE）建模。使用透视放射立体分析（fRSA）技术测量健康受试者足部骨骼的运动。该系统使用x射线对骨骼成像，同时测试对象执行动态任务，如直走和改变方向。在鞋内，使用鞋内压力传感系统直接测量鞋与脚的顶部和底部之间的压力。身体的整体运动是用光学动作捕捉来测量的。这三种系统以前从未被用于足部的研究。这个研究项目将大大提高我们对脚如何保持直立和活动的理解，以及鞋类和矫形器如何促进我们的活动。

The foot is structurally redundant. It is unlike the thigh or the lower leg where there are only one or two large bones and really only one way for biomechanical loads to be transmitted. The foot is instead a complex structure of 26 bones that each bear biomechanical load. An interesting fact is that about one quarter of the bones in the entire human body are in the two feet. This gives the foot a tremendous flexibility in how it transmits loads between the body and the ground. But how the foot does so is poorly understood. Connecting the ankle joint to the ground are five rays', or columns, of bones that start at the heel (calcaneus) and terminate at each of the toes. The first ray is also known as the medial longitudinal arch, the fifth ray is the lateral longitudinal arch. Each ray transmits a portion of the total biomechanical load from the body to the ground. But what proportion of the total load each ray bears cannot be calculated deterministically due to the foot's structural redundancy. It remains an open question how much load goes through each ray, whether the sharing of load is always the same, whether it changes from step to step, whether it changes during a step and whether it is the same between different people. This research program addresses the question of load sharing in the foot. It uses two complementary approaches, direct measurement on healthy test subjects performing dynamic tasks and finite element (FE) modeling of the foot anatomy, footwear and orthotics. The motion of the bones of the foot in healthy subjects is measured using the technique of fluoroscopic radio-stereometric analysis (fRSA). This system uses x-rays to image the bones while the test subject is performing dynamic tasks such as walking straight ahead and change directions. Within the shoe, the pressure between the footwear and the top and bottom of the foot is measured directly using an in-shoe pressure sensing system. The overall motion of the body is measured using optical motion capture. These three systems have never been combined for the study of the foot before. This program of research will significantly improve our understanding of how the feet keep us upright and mobile, and how footwear and orthotics can facilitate our mobility.