Many patients with knee disease often require knee replacement surgery in the advanced stages of the disease to obtain a pain-free and functional knee, but most patients do not really understand the relationship between the surgery and the expected outcome and believe that everything is fine once the surgery is successful and that a pain-free and functional knee has been “made”. This perception is very detrimental to a good surgical outcome. In fact, the essence of knee arthroplasty is twofold: 1) to replace the diseased and necrotic articular cartilage surface, and 2) to correct the lines of force to eliminate the existing deformity in order to obtain a normal anatomical relationship of the knee. Therefore, to be precise, knee arthroplasty itself only eliminates the lesion, corrects the deformity, and creates the “hardware” basis for a well-functioning and pain-free knee joint in the future, but to really achieve this goal, it needs the “software” of hard functional exercises after surgery. “to achieve this goal. Due to the surgical trauma and the pre-existing soft tissue lesions around the knee joint, the post-operative muscles and ligaments around the knee joint have been thoroughly loosened, resulting in edema and inflammation, so many patients are afraid to exercise after surgery for fear of pain, and always keep the knee joint in one position for a long time. Once the scar is formed, you can imagine that the knee joint will not be able to move anymore and will be stiff. At this point, it is safe to say that the surgery was done well for nothing. This is a race against the scarring of the soft tissues around the knee, and the earlier and more thorough the joint exercises, the better the postoperative results. The general requirement is that the knee should be able to flex at least 90 degrees and fully straighten within 2 weeks after knee replacement. Patients who are afraid of pain should exercise in conjunction with anti-inflammatory and analgesic medications. If good range of motion is still not obtained 3 months after surgery, you should promptly see your doctor for further management.