School of Kinesiology and NutritionThe University of Southern Mississippi Hattiesburg MS 39402 USA.
Department of Kinesiology and Health ScienceUtah State University Logan UT 84322 USA.
IEEE J Transl Eng Health Med. 2022 Dec 1;11:80-86. doi: 10.1109/JTEHM.2022.3226153. eCollection 2023.
Hip and knee flexion joint motions are frequently examined in clinical practice using camera based motion capture (CBMC) systems; however, these systems require elaborate setups and dedicated space. Inertial measurement unit (IMU) based systems avoid these disadvantages but require validation before widespread adoption. Moreover, it is important for clinical practice to determine the stability of these systems for prolonged evaluation periods. The purpose of this study was to assess the validity of a three-sensor inertial measurement unit system for calculating hip and knee flexion angles during gait by comparing with a gold standard CBMC system. Validity was also examined before and after a treadmill walking session.
Twenty healthy participants were tested. Twenty seconds of gait at preferred walking speed were analyzed before and after thirty-two minutes of treadmill walking using previously validated CBMC methods and with a custom IMU model. Measurement validity for the IMU system was evaluated using Bland & Altman 95 percent limits of agreement, linear regression, mean absolute error and root mean square error. The effects of a measurement zeroing calibration strategy were also investigated.
Strong measurement agreement was observed for both hip and knee flexion angles, although overall agreement for the hip exceeded that for the knee. Linear regressions between the datasets for each participant illustrated strong (> 0.94) relationships between IMU and CBMC measurements. More significant changes between timepoints were observed for the knee than for the hip. Error values were generally reduced when zeroing calibration was implemented.
The IMU system presented in this study is a convenient and accessible technique to measure joint angles. The protocol described in the current study can be easily applied in the clinical setting for evaluation of clinical populations. Additional development work on sensor placement and calibration methods may further increase the accuracy of such methods. Clinical translation statement: The IMU system presented in this study is a convenient and accessible technique to measure joint angles. Additional developmentwork on sensor placement and calibration methods may further increase the accuracy of such methods.
在临床实践中，常使用基于相机的运动捕捉 (CBMC) 系统来检查髋关节和膝关节的屈伸运动；然而，这些系统需要精心的设置和专用空间。基于惯性测量单元 (IMU) 的系统避免了这些缺点，但在广泛采用之前需要进行验证。此外，对于临床实践来说，确定这些系统在长时间评估期间的稳定性非常重要。本研究的目的是通过与黄金标准 CBMC 系统进行比较，评估三传感器惯性测量单元系统在步态中计算髋关节和膝关节屈伸角度的有效性。还在跑步机行走前后检查了有效性。
对 20 名健康参与者进行了测试。使用先前验证的 CBMC 方法和定制的 IMU 模型，在跑步机行走 32 分钟前后，分析了 20 秒的自然行走速度步态。使用 Bland & Altman 95%一致性界限、线性回归、平均绝对误差和均方根误差评估 IMU 系统的测量有效性。还研究了测量零点校准策略的效果。
观察到髋关节和膝关节屈伸角度的测量结果具有很强的一致性，尽管髋关节的整体一致性优于膝关节。每位参与者的数据集之间的线性回归表明，IMU 和 CBMC 测量之间存在很强的关系（>0.94）。与髋关节相比，膝关节的时间点之间的变化更为显著。实施零点校准后，误差值通常会降低。
本研究中提出的 IMU 系统是一种方便、可及的测量关节角度的技术。当前研究中描述的方案可在临床环境中轻松应用于临床人群的评估。进一步开发传感器放置和校准方法可能会进一步提高此类方法的准确性。
本研究中提出的 IMU 系统是一种方便、可及的测量关节角度的技术。进一步开发传感器放置和校准方法可能会进一步提高此类方法的准确性。
