Systems and corresponding methodologies that enable continuous, real-time or near real-time monitoring of joint activity of patients who are undergoing physical therapy is provided. A joint's motion patterns can be measured using a six degree of freedom combine accelerometer, magnometer and gyroscope sensors that are placed above and below (or in proximity of) the joint. The data is stored on a data logger that is carried by a patient, e.g., clipped to the patient's belt and can be uploaded onto a website when attached to a computer, e.g., via a USB cord. While portable sensors are available in the market for research or gaming purposes, one key feature of the device is to provide continuous monitoring of the injured joint and electronically relay this information to the therapist, for example, via the designated website. Thus, the therapist is always informed about the patient's joint and could recommend alterations to their treatment plan.