Background

Varus thrust during walking, visualized as excessive frontal plane knee motion during weight acceptance, is a modifiable risk factor for progression of knee osteoarthritis. However, visual assessment does not capture thrust severity and quantification with optical motion capture is often not feasible. Inertial sensors may provide a convenient alternative to optical motion capture. This proof-of-concept study sought to compare wearable inertial sensors to optical motion capture for the quantification of varus thrust.

Methods

Twenty-six participants with medial knee osteoarthritis underwent gait analysis at self-selected and fast speeds. Linear regression with generalized estimating equations assessed associations between peak knee adduction velocity or knee adduction excursion from optical motion capture and peak thigh or shank adduction velocity from two inertial sensors on the lower limb. Relationships between inertial measures and peak external knee adduction moment were assessed as a secondary aim.

Findings

Both thigh and shank inertial sensor measures were associated with the optical motion capture measures for both speeds (P < 0.001 to P = 0.020), with the thigh measures having less variability than the shank. After accounting for age, sex, body mass index, radiographic severity, and limb alignment, thigh adduction velocity was also associated with knee adduction moment at both speeds (both P < 0.001).

Interpretation

An inertial sensor placed on the mid-thigh can quantify varus thrust in people with medial knee osteoarthritis without the need for optical motion capture. This single sensor may be useful for risk screening or evaluating the effects of interventions in large samples.

中文翻译：

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使用可穿戴惯性传感器量化膝骨关节炎的内翻推力：概念证明

背景

行走过程中的内翻推力，表现为承受重量期间膝关节额面过度运动，是膝骨关节炎进展的一个可改变的危险因素。然而，视觉评估无法捕捉推力的严重程度，并且通过光学运动捕捉进行量化通常是不可行的。惯性传感器可以提供光学运动捕捉的便捷替代方案。这项概念验证研究旨在将可穿戴惯性传感器与光学运动捕捉进行比较，以量化内翻推力。

方法

二十六名患有内侧膝骨关节炎的参与者以自我选择的快速步态进行了分析。使用广义估计方程的线性回归评估了来自光学运动捕捉的峰值膝内收速度或膝内收偏移与来自下肢上的两个惯性传感器的峰值大腿或小腿内收速度之间的关联。惯性测量与峰值外膝内收力矩之间的关系被评估为次要目标。

发现

大腿和小腿惯性传感器测量值均与两种速度的光学运动捕捉测量值相关（P  < 0.001 至P  = 0.020），大腿测量值的变异性小于小腿测量值。在考虑了年龄、性别、体重指数、射线照相严重程度和肢体对齐后，两种速度下大腿内收速度也与膝内收力矩相关（均P  < 0.001）。

解释

放置在大腿中部的惯性传感器可以量化膝关节内侧骨关节炎患者的内翻推力，而无需光学运动捕捉。这种单一传感器可用于风险筛查或评估大样本干预措施的效果。