Why do I need rehabilitation? After an illness, injury, or surgery, the body will have certain deficits in function. A small percentage of these deficits may recover on their own. However, most of the functions can only be gradually restored or compensated after a certain period of time with timely and proper rehabilitation and functional exercises, so as to achieve the goal of restoring functions and returning to society. Post-operative rehabilitation is the guarantee of the surgical effect: good post-operative function comes from timely and correct rehabilitation of the patient’s own conditions and active cooperation. Therefore, rehabilitation is not just a passive treatment. Only with the active cooperation of the patient and the joint efforts of the doctor and the patient can we achieve the best possible results and avoid complications, sequelae and loss of function. The three basic principles of rehabilitation medicine are: functional exercise, full rehabilitation and social reintegration.