Development of an electronic platform to quantify human knee function

Abstract

The purpose of the presented study is to determine whether wearable motion analyzers are suitable for monitoring and measuring human knee function. This study focuses on the selection and placement of sensors that can provide data on knee function during daily living activities at home, such as Activity 3: Standing and sitting, putting on shoes, and climbing and descending hills and stairs. Once the biomechanics of the knee and the types of measurements needed to monitor knee function were introduced, it was decided that we needed to measure knee joint angle, knee joint angular velocity, and ground reaction force. A sensor platform was developed to collect data for wearable motion analysis. Accelerometers were used to measure knee joint angle, gyroscopes were used to measure knee joint angular velocity, and Velostat force sensors were used to measure heel and forefoot ground reaction forces. Fifteen participants were recruited for this study, but only thirteen of them were available for knee angle and knee angular velocity data and eight for ground reaction force data. Knee joint angles, knee joint angular velocities, and ground reaction force data were collected for everyday activities like tying shoelaces, standing/sitting, climbing/descending slopes, climbing/descending stairs, and walking. Knee joint angle and knee joint angular velocity results were compared with the Qualysis motion capture system for validation. For validation, the ground reaction force was compared with force plates. The results obtained for knee joint angle and knee joint angular velocity are very similar to those of the Qualyisis motion capture system, which may be useful for everyday motion capture, but based on our analysis of the effectiveness of the sensor platform, it is not ready yet for clinical application while the device is in early stages development and thus requires adjustments. Ground reaction force data obtained from the sensor platform varies greatly. Some areas of the force curve have similar mean values as that of the force plates, but the force readings from the sensor platform vary too much to be reliable for everyday use.