The development of kinematic and kinetic multisegment foot models for gait analysis

多年来，使用运动捕捉系统和力学模型测量人体肌肉骨骼的运动和力一直是研究中常用的方法。到目前为止，大多数步态研究都将脚建模为包含两个旋转自由度的单个刚性分段，或者建模为具有一个自由度的矢量。这些简单化的模型限制了我们对脚部非常复杂的多关节结构的理解。为了增加我们对典型和非典型足部力学的了解，最近发展了多节段足部力学模型。这些模型将脚分为多个隔室或节段，从而可以测量节段之间的相对运动。到目前为止，大多数多段脚模型本质上都是运动学的。在这些模型中，使用的分段数和反射标记的位置差别很大。在解剖参照系的位置和方向以及用于计算角度的方法上还可以发现进一步的差异。由于缺乏标准化，很难在不同研究之间进行比较。对多种足部模型的比较研究将为定义和分析足部力学的最佳方法提供洞察力。到目前为止，对多种足部模型的比较研究很少，在足部模型的方法学设计上需要更大的一致性。 只有5项研究检验了运动性多节段足部模型。多节段运动学模型可以提供对典型和非典型足部力学的更深入的了解。这些研究受到样本量小、不同的足部模型和技术限制的限制。例如，在步态过程中同时测量剪切力、垂直力和压力的最佳方法存在很大争议(即，测力板不提供关于脚部位置或脚下载荷分布的信息)。相比之下，压力垫提供了足部位置、载荷分布和垂直反作用力的数据，但不能量化前后或内侧方向的剪切力)。对使用测力板与测力板和压力垫获得动力学数据的各种手段进行比较的研究，可以提供关于当前动力学模型基本假设的影响的重要信息。 由于多节段足部研究在生物力学中是一个相对较新的领域，影响足部运动的因素也没有得到很好的了解。关于年龄、步行速度、性别和弓形类型对步态中多节段足部力学的影响的研究很少。此外，必须解决建模和技术问题，以便在研究中广泛使用这些模型。由于脚有助于减震，并在行走过程中提供支撑和推进动力，因此研究人员必须更好地了解这一复杂部分的作用。这项研究的长期目标是：1)建立最佳的足部力学模型和测力技术，2)增加我们对典型人群中足部力学的理解。这项工作有四个短期目标：1)检查3个多节段足部模型对运动学和运动学步态测量的影响，2)比较3个多节段足部模型使用力板和力/压力垫计算的关节动力学，3)研究年龄、性别和弓形类型对步态中多节段足部力学的影响，4)研究步态中步行速度对多节段足部力学的影响。

The measurement of human musculoskeletal motion and forces using motion capture systems and mechanical models has been routinely used in research for many years. To date, most gait research has modeled the foot as a single rigid segment consisting of two rotational degrees of freedom, or as a vector with one degree of freedom. These simplistic models limit our understanding of the very complex multi-joint structure of the foot. To increase our knowledge of the mechanics of the typical and atypical foot, multisegment mechanical models of the foot have recently been developed. These models divide the foot into multiple compartments or segments allowing the relative motion between segments to be measured. To date, most multisegment foot models have been kinematic in nature. The number of segments used and the locations of reflective markers vary greatly across these models. Further differences can be found in the location and orientation of anatomical reference frames and the methods used to compute angles. This lack of standardization makes it difficult to compare across studies. A comparative study of multiple foot models would provide insight on optimal methods of defining and analyzing the mechanics of the foot. To date, few comparative studies of multiple foot models exist and a greater consistency in the methodological design of foot models is required. Only 5 studies have examined kinetic multisegment foot models. Multisegment kinetic models may provide greater insight into typical and atypical foot mechanics. These studies have been limited by small sample sizes, varying foot models, and technological limitations. For example, great controversy exists over the best way to simultaneously measure shear forces, vertical forces, and pressure during gait (i.e. force plates do not provide information on the location of the foot or the distribution of load under the foot). In contrast, pressure mats provide data on foot location, load distribution, and vertical reaction forces but do not quantify shear force in the anteroposterior or mediolateral directions). Studies that compare various means of obtaining kinetic data using force plates versus force plates and pressure mats could provide important information on the effects of the underlying assumptions of current kinetic models. As multisegment foot research is a relatively new field in biomechanics, the factors that affect foot motion are also not well understood. Very little research exists on the effects of age, walking speed, gender, and arch type on multisegment foot mechanics during gait. In addition, modeling and technological issues must be addressed in order for these models to be used extensively in research. As the foot aids in shock absorption and provides a base of support and propulsive power during walking, it is essential that researchers gain a greater understanding of the role of this complex segment. The long-term goals of this research program are to: 1) establish optimal foot mechanical models and force measurement techniques, and 2) increase our understanding of foot mechanics in typical populations. This work has four short-term objectives: 1) to examine the effects of 3 multisegment foot models on kinematic and kinetic gait measures, 2) to compare joint kinetics computed using force plates versus force/pressure mats for the 3 multisegment foot models, 3) to examine the effects of age, gender, and arch type on multisegment foot mechanics during gait, and 4) to examine the effects of walking speed on multisegment foot mechanics during gait.