First approach to automatic measurement of frontal plane projection angle during single leg landing based on depth video

Knee alignment measurements are one of the most extended indicators of knee complex injuries such as anterior cruciate ligament injury and patellofemoral pain syndrome. The Frontal Plane Projection Angle (FPPA) is widely used as a 2D estimation of knee alignment. However, traditional procedures to measure this angle suffer from practical limitations, which leads to huge time investments when evaluating multiple subjects. This work presents a novel video analysis system aimed at supporting experts in the dynamic measurement of the FPPA in a cost effective and easy way. The system employs Kinect V2 depth sensor to track reflective markers attached to the patient leg joints to provide an automatic estimation of the angle formed by the hip, knee and ankle joints. Information registered by the sensor is processed and managed by a computer application that simplifies expert’s work and expedites the analysis of the test results.