Evaluating accuracy and usability of Microsoft Kinect sensors and wearable sensor for tele knee rehabilitation after knee operation

The Microsoft Kinect sensors and wearable sensors are considered as low-cost portable alternative of advanced marker-based motion capture systems for tracking human physical activities. These sensors are widely utilized in several clinical applications. Many studies were conducted to evaluate accuracy, reliability, and usability of the Microsoft Kinect sensors for tracking in static body postures, gait and other daily activities. This study was aimed to asses and compare accuracy and usability of both generation of the Microsoft Kinect sensors and wearable sensors for tracking daily knee rehabilitation exercises. Hence, several common exercises for knee rehabilitation were utilized. Knee angle was estimated as an outcome. The results indicated only second generation of Microsoft Kinect sensors and wearable sensors had acceptable accuracy, where average root mean square error for Microsoft Kinect v2, accelerometers and inertial measure units were 2.09°, 3.11°, and 4.93° respectively. Both generation of Microsoft Kinect sensors were unsuccessful to track joint position while the subject was lying in a bed. This limitation may argue usability of Microsoft Kinect sensors for knee rehabilitation applications.