Background

Hop tests are commonly used in clinical environments to measure function after sport-related knee injuries. Joint angle measurement during hopping is feasible in research-based environments equipped with motion-capture systems. Employing these systems in clinical research settings is inefficient, given the associated cost, preparation time, and expertise required to administer and interpret the findings. Therefore, this study aimed to introduce a wearable system comprising three inertial measurement units for 3D joint angular measurement during horizontal hop tests, validate the joint angles against a camera-based system, and evaluate its applicability in clinical research environments.

Methods

Ten able-bodied participants were outfitted with three inertial measurement units during triple single-leg hop trials. 3D knee and ankle angles were calculated using the strap-down integration method, and results were compared with camera-based joint angles. Additionally, knee and ankle range of motions (RoMs) during bilateral triple single-leg hop trials were compared for 22 participants with unilateral sport-related knee injuries and 10 uninjured participants.

Findings

Estimated angles had root-mean-square and RoM error medians of less than 2.3 and 3.2 degrees for both joints, and correlation coefficients of above 0.92 when compared with the camera-based system, for all hop phases. Injured participants had smaller sagittal ankle RoM (P = .008) on their injured side, during the third hop. Concurrently, they demonstrated smaller knee RoM symmetry indices (P = .017) and injured knee sagittal RoMs (P = .009) compared to uninjured participants.

Interpretation

The introduced system had appropriate accuracy to highlight post-injury modifications in hopping kinematics and reveal noteworthy differences in RoM of clinical samples.

中文翻译：

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仪器式三重单腿跳跃测试：一种使用惯性传感器动态测量踝关节和膝盖角度的有效方法。

背景

跳跃测试通常在临床环境中用于测量与运动有关的膝盖受伤后的功能。在配备运动捕捉系统的基于研究的环境中，跳跃期间的关节角度测量是可行的。考虑到相关的成本，准备时间以及管理和解释研究结果所需的专业知识，在临床研究环境中使用这些系统效率低下。因此，本研究旨在介绍一种可穿戴系统，该系统包括三个惯性测量单元，用于水平跳测试中的3D关节角度测量，针对基于相机的系统验证关节角度，并评估其在临床研究环境中的适用性。

方法

在三重单腿跳试验中，有十个身体健全的参与者配备了三个惯性测量单元。使用捷联积分法计算3D膝盖和踝关节的角度，并将结果与​​基于摄像头的关节角度进行比较。此外，比较了22例单侧与运动相关的膝盖受伤参与者和10例未受伤参与者的双边三重单腿跳跃试验期间的膝盖和踝关节活动范围（RoM）。

发现

对于所有跃点阶段，两个关节的估计角度的均方根和RoM误差均值均小于2.3和3.2度，与基于摄像头的系统相比，相关系数均大于0.92。 在第三跳期间，受伤的参与者受伤侧的矢状踝RoM较小（P = 0.008）。同时， 与未受伤的参与者相比，他们的膝盖RoM对称性指数更小（P  = .017），受伤的膝盖矢状RoMs（P = .009 ）。

解释

引入的系统具有适当的准确性，可以突出显示跳跃运动学中的损伤后修改，并揭示临床样品的RoM方面的显着差异。