Mijailovie et al. combined the use of an accelerometer and two gyroscopes for determining the mobility of the spinal column. Toa et al. [4] proposed a method for home-based rehabilitation using vision and inertial sensors to track the arm movement. In [5], Bin Ambar et al. proposed the use of sensors combination (flex sensor, force sensitive sensor and accelerometer) for developing a wearable arm rehabilitation monitoring device. Cifuentes et al. [6] presented a tool for assessment and therapy in post-stroke upper-limb rehabilitation. The wireless wearable sensor system consists of a ZigBee network, IMU and surface Electromyography sensors. Pnadilha et al. [7] proposed a method for sensor calibration. In the study, a 3-axis accelerometer, a 2-axis gyroscope and Kinect are used for joint angle estimation. Online calibration was developed based on Kalman filtering to combine the data from both inertial sensor and Kinect to improve the overall estimated motion. Many research studies reported that senaor-based tools for rehabilitation is still not 100% accurate, however, an error of ±5° in goniometry measures is suggested as an acceptable range for several clinical circumstances [8].