Since the artificial knee tibial spacer is a polyethylene material, the wear resistance has not yet reached perfection. Therefore, the age for artificial knee replacement is generally set at 55 years or older. Because the patient is not as active as a young person at this time and the joint is not as worn, surgery at this time can meet the needs of daily life while not having to worry about frequent re-replacement. However, the age is not absolute. If the knee pain is significant and conservative treatment does not work, the age can be relaxed, but the joint should be replaced with a better design and more wear-resistant material. Is there an upper age limit? Theoretically, there is not. As long as the medical condition can tolerate the surgery, it can be replaced. However, the older you are, the greater the risk of surgery and the less time you will have to enjoy the joint after replacement. Therefore, in this era of emphasis on quality of life, if it becomes necessary to replace the knee joint, early surgery is recommended. What factors are involved in the surgical outcome of knee replacement A common question asked by patients is why some people walk as fast as they can after surgery, while others still walk with crutches. As a joint surgeon, I know that the surgical technique is important for a good knee replacement surgery, but it is also important to have a well-designed and rigorous rehabilitation plan and to have the patient’s full cooperation. The result of surgery is “6 points of work, 4 points of practice”. If the joint is well designed, but not placed on the normal knee joint force line, the wear and tear of the prosthesis is bound to increase, shortening the life of the prosthesis, and making it easier for conditions such as anterior knee pain and patellar dislocation to occur. In addition, for artificial knee replacement surgery, the sterile environment of the operating room is very demanding, i.e., it is required to operate in a class 100 laminar flow operating room (<100 colonies per cubic meter). Otherwise, in case of infection, the replaced joint must be removed. Therefore, it is important to go to a major hospital for surgery. The surgery is perfect, and if the patient cannot cooperate with the surgeon in rehabilitation exercises, the range of motion of the replaced knee joint is limited and it will not meet the requirements. Rehabilitation exercises are tough and cannot be achieved without pain. Of course, there are analgesic measures available to reduce pain. Finally, the psychological factors of the patient are also important. Pre-operative communication between the doctor, patient and family is important. The determination to do the surgery should be made by the patient himself, and the patient should respond to the surgery with a normal mind before the surgery and not have too high expectations. The higher the expectations, the higher the disappointment when the postoperative recovery period is difficult. Relief of pain and improvement of knee function is the main goal of surgery.