Artificial knee arthroplasty is a very effective surgery with an excellent rate of >90%, but patients should not simply place the success of the surgery on the skill of the surgeon, but should also pay attention to post-operative functional rehabilitation and observation of the post-replacement knee, which directly affects the future use of the joint. Some patients are not prepared for the normal reactions that often occur after artificial knee replacement, and they often mistake some normal phenomena in the postoperative rehabilitation process as “something wrong”, which increases many unnecessary worries and in some cases even directly affects the patient’s desire for rehabilitation and delays the normal conduct of rehabilitation training. Some of them even directly affect the patient’s desire for rehabilitation, delaying the normal rehabilitation training, which is not conducive to the maintenance of the patient’s improved joint function after surgery and further affects the improvement of quality of life. We have summarized some regular phenomena that occur in the rehabilitation process of patients after total knee arthroplasty, some of these signs are normal phenomena that are bound to occur and will surely get better gradually, while others should be alerted enough to draw the attention of patients and help them to put down their ideological “baggage”. 1, around the wound appears “numbness” or “over the electricity-like” scurrying pain. This is due to the regeneration of the neurocutaneous branch that governs the skin on the outside of the surgical incision, and when the nerve regeneration process breaks through the scar, it produces an “over-electric” pain sensation. 2. The affected knee joint has swelling and heat sensation. Within 3 months after surgery, the affected knee joint is often. This is due to the inflammation caused by the body’s reaction to the prosthesis or the stimulation of knee joint activities during functional training. This inflammation is not caused by bacterial infection, but it also has the characteristics of redness, swelling, heat and pain; a small amount of joint effusion facilitates the lubricating effect of joint activities. These symptoms can gradually disappear and return to normal within six months after surgery. If there is significant swelling, heat, redness or fluid in the affected knee, you should pay attention to it and consult your doctor to determine if there is a late post-operative infection. 3. The affected knee always feels tight around the joint. This is mainly due to the formation of the postoperative scar, which is gradually “pulled apart” and released through functional exercises. This is mainly due to the scar formation after surgery. 4. The affected knee is painful or sore at night and has a stiff feeling when waking up in the morning. During the postoperative rehabilitation process, as the intensity and frequency of training increases, some patients may experience soreness in the affected knee at night and stiffness in the knee when they wake up in the morning, especially after greater activity during the day. This is a normal response during the rehabilitation process after total knee replacement. The degree of pain is related to the patient’s preoperative functional status of the knee, and the lower the preoperative functional score of the knee, the more pronounced the pain due to training may be. If activity and exercise are more intense during the day, an oral pain medication similar to fenbendazole can be taken after dinner or a topical analgesic and anti-inflammatory drug such as fotarine emulsion can be used to inhibit soft tissue edema and pain. On the basis of excluding other complications, patients should build up confidence to overcome the disease and achieve the best functional rehabilitation through active exercises. 5. Stiffness or unnaturalness when walking. After arthroplasty, as long as the patient can take care of daily activities without joint pain, and the joint flexion and extension reach the expected level, the expected result can be considered. Early postoperative stiffness is normal and can be relieved to varying degrees in 6-8 weeks with effective functional exercises, with further improvement with functional exercises. In addition to soft tissue scar formation and unrecovered soft tissue edema, there are many causes of post-operative knee stiffness, which are related to the incomplete recovery of the muscles around the joint, and are often most apparent in the morning when walking on the ground. Whether or not the stiffness of the joint is relieved can be used as an indicator to assess the effectiveness of rehabilitation, which is normal during the above mentioned time. 6. The “gurgling sound” during post-operative knee activities. This sound is generally due to the fact that the soft tissue around the newly installed prosthesis is still flaccid, the muscles are weak, and there is a lack of sufficient strength to maintain balance. The above-mentioned rattling sound occurs during the postoperative activity of the prosthesis, especially when there is a collision between the patella and the femoral condyle prosthesis. This ringing is rarely accompanied by clinical symptoms, but can cause tension in the patient. Over time, after the soft tissues have repaired and balanced themselves, the rattling of these patients’ joints will gradually disappear and no special treatment is required. If the symptoms are very pronounced, consult a physician to rule out problems such as poor patellar trajectory. 7. Joint flexion and extension exercises. Straightening exercises: you can use sandbags to press the leg for 20-30 minutes three times a day; flexion exercises should be trained 8-10 times a day, striving to exceed 90° each time. If trained properly, it is possible to achieve 120° of knee flexion. Some discomfort may occur during functional exercise, including swelling, mild pain, and fever; this is normal as long as it is not severe. The amount of training should be small to large and gradual, so as not to cause significant discomfort in the affected knee. It should last for more than six months. 8. The above is normal. What phenomenon must I see the doctor immediately? Late postoperative infection is the most serious complication after artificial joint replacement, and in severe cases, the prosthesis even has to be removed, thus easily leading to complete failure of the artificial joint. Symptoms of infection are usually significant localized warmth, redness or a large amount of fluid in the affected knee. When a patient has a cold or other acute infection, antibacterial agents should be given to prevent infection; if you find local redness, swelling or a “red bag” protruding from the affected knee, you should go to the hospital immediately and not to a non-specialized clinic to avoid delay or wrong treatment. Recommendations: In addition to taking advantage of the outpatient review opportunity to receive professional advice on the prosthesis and functional recovery of the affected knee after discharge, patients should consult with a medical professional to identify any other problems that may arise during the late recovery process.