Sheridan Gerard A, Keenan Gráinne, Beverland David E
Department of Orthopaedics, Musgrave Park Hospital, Belfast, Ireland.
Arthroplast Today. 2022 Jan 17;14:205-209.e2. doi: 10.1016/j.artd.2021.11.012. eCollection 2022 Apr.
Virtual patient assessment will inevitably require smartphone technology to remotely measure knee range of motion. We conducted an experiment to analyze the impact of observer position relative to the flexed knee on the perceived angle measured using an electronic application (Dr. Goniometer) for iPhone. Two observers measured the apparent knee flexion angle from 7 different positions at 3 different heights relative to the center of the knee joint. Intraclass correlations were calculated to evaluate the intraobserver and interobserver variability using two-way mixed-effects models. The intraclass correlation for interobserver variability was excellent at 0.804 (95% confidence interval 0.663-0.889). When the observer was greater than 15° from the knee perpendicular, the true angle of knee flexion (90°) was not observed in any of the measurements. This was the case when observed from both proximal (range 95°-121°) and distal (range 92°-108°) directions. Ideally the camera lens should be perpendicular to the long axis of the lower limb in the proximal-distal direction and at the same height. However, if the camera lens is within 15° of the perpendicular, then at 90° of true flexion, the perceived angle will not be greater than 95° in 94% of cases.
虚拟患者评估将不可避免地需要智能手机技术来远程测量膝关节活动范围。我们进行了一项实验，以分析观察者相对于屈曲膝关节的位置对使用适用于iPhone的电子应用程序（角度计博士）测量的感知角度的影响。两名观察者在相对于膝关节中心的3个不同高度处，从7个不同位置测量了明显的膝关节屈曲角度。使用双向混合效应模型计算组内相关性，以评估观察者内和观察者间的变异性。观察者间变异性的组内相关性极佳，为0.804（95%置信区间0.663 - 0.889）。当观察者与膝关节垂线的夹角大于15°时，在任何测量中均未观察到膝关节真正的屈曲角度（90°）。从近端（范围95° - 121°）和远端（范围92° - 108°）方向观察时都是如此。理想情况下，相机镜头应在近端 - 远端方向上与下肢长轴垂直且处于同一高度。然而，如果相机镜头与垂线的夹角在15°以内，那么在真正屈曲90°时，94%的情况下感知角度不会大于95°。
