Purpose The aim of this study was to establish the concurrent validity and reliability of four different two-dimensional (2D) video-based techniques for quantifying frontal plane knee kinematics during a 40 cm double-legged drop jump. Participants and methods A convenience sample of 16 healthy participants (nine males and seven females; age: [mean ± standard deviation] 25.5±2 years; body mass index: 24.33±2.98 kg/m2) participated in this investigation. A total of five trials during a 40 cm drop jump maneuver with a countermovement jump were used as the functional task. Four knee valgus measures, such as two different frontal plane projection angle measures, knee-to-ankle separation ratio (KASR), and knee separation distance (KSD), were measured using 2D and three-dimensional (3D) systems. To generalize to the greater population of possible evaluators, the testers performing the biomechanical analyses were three novice physical therapists. Intra- and intertester intraclass correlation coefficients (ICCs) were estimated for 2D analysis variables. ICCs were estimated for all measures between systems to determine concurrent validity of the 2D system. Results All four 2D measures showed good to excellent reliability (ICC: 0.89–0.99). KASR and KSD showed excellent correlation (ICC: 0.96; 95% CI: 0.82–0.98 and ICC: 0.94; 95% CI: 0.90–0.96, respectively) with the 3D system, while both methods of frontal plane projection angle showed poor to moderate correlation (ICC: 0–0.57) with the 3D system. Conclusion 2D KASR and KSD measures are cost effective, reliable, and highly correlated with the same measures using 3D techniques for the evaluation of knee valgus.

中文翻译：

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跳跳过程中膝外翻的二维和三维评估之间的可靠性和并行有效性

目的这项研究的目的是要建立四种不同的基于二维（2D）视频的技术的并发有效性和可靠性，这些技术用于量化40厘米双腿摔跤过程中额平面膝关节运动学。参与者和方法本研究以16名健康参与者（9名男性和7名女性；年龄：[平均值±标准差] 25.5±2岁；体重指数：24.33±2.98 kg / m2）的便利样本参加。在一次40厘米的跳跳动作中以反跳动作进行的总共5次试验被用作功能任务。使用2D和3D（3D）系统测量了四个膝外翻测量值，例如两个不同的额平面投影角度测量值，膝踝分离比（KASR）和膝分离距离（KSD）。为了推广到更多可能的评估人员，进行生物力学分析的测试人员是三位新手物理治疗师。对于2D分析变量，估计了测试者内部和测试者内部的类内相关系数（ICC）。对系统之间所有措施的ICC进行估算，以确定2D系统的并发有效性。结果所有4个2D度量均显示出良好至极好的可靠性（ICC：0.89–0.99）。KASR和KSD与3D系统显示出极好的相关性（ICC：0.96； 95％CI：0.82-0.98和ICC：0.94； 95％CI：0.90-0.96），而两种方法的前平面投影角均显示差至中等与3D系统的相关性（ICC：0–0.57）。结论2D KASR和KSD措施经济高效，可靠，