Abstract
Patients suffering from knee joint damage are generally only provided with subjective, qualitative feedback form physicians. This research sets the foundation for providing a quantitative, non-invasive feedback for knee joint damage by finding the center of rotation (CoR) of the knee joint. Knee joint motion analysis is usually performed through camera based optical tracking systems. Although these standard technologies allow a complete 3-D kinematics of knee, they require a dedicated laboratory. In this research a novel method of utilizing IMUs to obtain knee CoR is proposed. The merits of utilizing IMUs derives from its compact size, short diagnose time, thus putting less burden on patients. With IMU, acceleration and angular velocity can be measured. IMUs were fixed to the thigh and shank to measure the instantaneous CoR of the knee. Since the instantaneous CoR of the knee is different during normal and damaged condition, by obtaining the instantaneous CoR of the knee, one can quantitatively evaluate the conditions of the knee and provide outcome evaluation after surgery. It was found that for extension motion, good correlation coefficient was obtained from IMU and camera. However flexion motion showed much larger result than camera. This is assumed as the effect of inertia. In addition, calculating a 3D motion in a 2D plane may be a crucial reason effecting results. However it can be concluded that utilizing IMUs to diagnose knee function is adoptable in clinical fields for its easy accessibility and less burdens on patients.
