Ability of a multi-segment foot model to measure kinematic differences in cavus, neutrally aligned, asymptomatic planus, and symptomatic planus foot types

Background Multi-segment foot models (MFMs) provide a better understanding of the intricate biomechanics of the foot, yet it is unclear if they accurately differentiate foot type function during locomotion. Research question We employed an MFM to detect subtle kinematic differences between foot types, including: pes cavus, neutrally aligned, and asymptomatic and symptomatic pes planus. The study investigates how variable the results of this MFM are and if it can detect kinematic differences between pathologic and non-pathologic foot types during the stance phase of gait. Methods Independently, three raters instrumented three subjects on three days to assess variability. In a separate cohort, each foot type was statically quantified for ten subjects per group. Each subject walked while instrumented with a four-segment foot model to assess static alignment and foot motion during the stance phase of gait. Statistical analysis performed with a linear mixed effects regression. Results Model variability was highest for between-day and lowest for between–rater, with all variability measures being within the true sample variance. Almost all static measures (radiographic, digital scan, and kinematic markers) differed significantly by foot type. Sagittal hindfoot to leg and forefoot to leg kinematics differed between foot types during late stance, as well as coronal hallux to forefoot range of motion. The MFM had low between-rater variability and may be suitable for multiple raters to apply to a single study sample without introducing significant error. The model, however, only detected a few dynamic differences, with the most dramatic being the hallux to forefoot coronal plane range of motion. Significance: Results only somewhat aligned with previous work. It remains unclear if the MFM is sensitive enough to accurately detect different motion between foot types (pathologic and non-pathologic). A more accurate method of tracking foot bone motion (e.g., biplane fluoroscopy) may be needed to address this question.

背景 多节段足部模型（MFMs）能更好地理解足部复杂的生物力学，但尚不清楚它们在运动过程中是否能准确区分足部类型的功能。 研究问题 我们采用一种多节段足部模型来检测不同足部类型之间细微的运动学差异，包括：高弓足、正常排列以及无症状和有症状的扁平足。该研究调查这种多节段足部模型的结果有多大差异，以及它是否能在步态的站立阶段检测出病理和非病理足部类型之间的运动学差异。 方法 三名评估者在三天内分别对三名受试者进行仪器测量以评估变异性。在另一个队列中，对每组十名受试者的每种足部类型进行静态量化。每名受试者在佩戴四节段足部模型的情况下行走，以评估步态站立阶段的静态排列和足部运动。采用线性混合效应回归进行统计分析。 结果 模型的变异性在不同日期之间最高，在不同评估者之间最低，所有变异性指标都在真实样本方差范围内。几乎所有静态测量指标（影像学、数字扫描和运动学标记）都因足部类型不同而存在显著差异。在站立后期，不同足部类型的后足与小腿以及前足与小腿的矢状面运动学存在差异，拇趾与前足的冠状面活动范围也存在差异。多节段足部模型在不同评估者之间的变异性较低，可能适合多名评估者应用于单个研究样本而不会引入显著误差。然而，该模型仅检测到少数动态差异，其中最显著的是拇趾与前足冠状面的活动范围。 意义：结果仅在一定程度上与先前的研究一致。目前仍不清楚多节段足部模型是否足够灵敏，能够准确检测足部类型（病理和非病理）之间的不同运动。可能需要一种更准确的追踪足部骨骼运动的方法（例如，双平面透视）来解决这个问题。