Background

Although commonly used to study knee osteoarthritis (OA), relatively little is known about the reliability and validity of three-dimensional (3D) gait biomechanics derived from treadmill-based systems.

Research question

Using a treadmill-based gait analysis system, our objectives were to: 1) estimate the test-retest reliability of frontal and sagittal plane knee angles and moments in knee OA patients; 2) examine concurrent validity by estimating the associations between treadmill-based and overground (gold standard) measures; and 3) examine known-groups validity by comparing measures between knee OA patients and matched healthy controls.

Methods

34 patients and 16 controls completed 3D gait analyses using treadmill-based and overground systems. Treadmill walking speed was matched to self-selected overground speed. Marker set, knee angle and moment calculations were consistent for both systems. Patients completed a second test session using the treadmill-based system <24 h later but within 1 week of the first test session. Variables calculated from knee angle and moment gait waveforms during stance were evaluated using Bland and Altman plots, Intraclass Correlation Coefficients (ICC), Pearson correlations (r) and t-tests.

Results

Visual inspection of the Bland and Altman plots did not reveal any systematic differences between test and retest sessions; however, limits of agreement (LoA) were larger for the sagittal plane than the frontal plane. Mean differences between sessions for knee angles were <0.25 degrees and <0.18 %BW*ht for knee moments. ICCs ranged from 0.57-to-0.93 for test-retest reliability. Pearson correlations between treadmill and overground systems ranged from 0.56-to-0.97. Although highly associated, there were substantial differences in the moments, emphasizing they cannot be used interchangeably. Patients had greater first peak knee adduction moments (KAM) than controls [mean difference (95 %CI): 0.55 (−1.07, −0.04), p = 0.03].

Significance

Results suggest frontal and sagittal plane knee angles and moments in patients with knee OA evaluated using a treadmill-based system are reliable and valid.

中文翻译：

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使用基于跑步机的步态分析系统，对骨关节炎患者膝关节角度和力矩的可靠性和有效性进行分析。

背景

尽管通常用于研究膝关节骨关节炎（OA），但对基于跑步机系统的三维（3D）步态生物力学的可靠性和有效性知之甚少。

研究问题

使用基于跑步机的步态分析系统，我们的目标是：1）评估OA膝关节前额和矢状面膝关节角度和力矩的重测信度；2）通过估计跑步机和地面（金标准）措施之间的关联来检验并发有效性；3）通过比较膝盖OA患者和相匹配的健康对照者之间的措施，检查已知人群的有效性。

方法

34位患者和16位对照使用基于跑步机和地面的系统完成了3D步态分析。跑步机的行走速度与自行选择的地面速度相匹配。两种系统的记号设置，膝盖角度和力矩计算均一致。患者使用基于跑步机的系统完成了第二次测试，少于24小时，但在第一次测试的1周内。使用Bland和Altman图，类内相关系数（ICC），Pearson相关（r）和t检验评估从站立时的膝盖角度和步态步态波形计算出的变量。

结果

目视检查Bland和Altman的图并没有发现测试和重测之间的系统差异。但是，矢状面的一致性极限（LoA）大于额面。膝关节弯度之间的平均差异为<0.25度和<0.18％BW * ht。ICC范围从0.57到0.93，以确保重测的可靠性。跑步机和地面系统之间的Pearson相关性介于0.56-0.97之间。尽管联系紧密，但时刻之间还是存在很大差异，强调它们不能互换使用。患者的第一膝关节内收峰值（KAM）高于对照组[平均差异（95％CI）：0.55（-1.07，-0.04），p = 0.03]。

意义

结果表明，使用基于跑步机的系统评估的膝骨关节炎患者的额面和矢状面膝关节角度和力矩是可靠且有效的。