Does a knee replacement involve replacing the entire knee joint? This is a misconception. Many people mistakenly believe that joint replacement means replacing all of the joint, but in fact, joint replacement, also known as surface replacement, is the equivalent of replacing parts of the joint. Specifically, because the cartilage on the surface of the knee joint is worn out, a joint replacement only replaces this layer of cartilage, which is a very thin layer on the surface, and then a metal joint is placed over it, which is similar to putting a brace on a broken tooth. Finally, a “plastic pad”, a high-density polyethylene joint surface, is added between the two metal joints for shock absorption. This allows the patient to regain normal joint function and reduces pain. After knee replacement, will I be able to function like a normal person? To what extent can I recover? The goal of knee replacement is to reduce pain and restore basic function to the joint. After surgery, normal walking and basic living are fine, but kneeling and squatting are only possible for patients who have recovered exceptionally well, and most patients are unable to squat or move vigorously after surgery. Most patients are unable to squat or do strenuous activities after surgery. Especially if the patient performs strenuous activities like an athlete after surgery, it will increase the wear and tear on the joint. Will I still have pain and other symptoms after surgery? There are two stages of post-operative pain. In the first stage, pain occurs after the anesthesia has passed, which is caused by the surgery and will disappear over time. In particular, this post-operative pain is much less severe than the pain caused by the disease before surgery, and the surgeon will use various methods, such as analgesics, to eliminate the pain during the process. In the second stage, after the postoperative joint function is restored, the pain will gradually disappear in more than 95% of patients. According to my experience, about 1/3 of the patients feel that the new artificial joint is as suitable as their own joint one year after surgery, and they do not feel any pain; 1/3 of the patients occasionally feel a little discomfort and pain when it is rainy or cloudy after surgery, which is also normal, because it is an artificial joint after all, and it has a wear and tear process with itself; and 1/3 of the patients have pain because of joint adhesion or functional exercise. In another 1/3 of patients, the pain is caused by joint adhesions or untimely functional exercises, but this pain is much less than the joint pain before surgery and basically does not affect life. What are the problems if I don’t have a knee replacement? The first thing we need to understand is why we need a joint replacement. The surface of the knee joint has a layer of cartilage, which is often called “brittle bone”, and it has no nerves. For a variety of reasons, such as rheumatoid arthritis, ankylosing spondylitis, and joint injury, the cartilage wears away, exposing the bone beneath the cartilage. Unlike cartilage, there are nerves inside the bone, and when the bone wears away, the patient feels pain, and this pain can have an impact on life. In the early stages, the pain may only be felt when there is more movement, and for patients in their 50s and 60s, they may be hesitant to have surgery. By the time the disease has progressed to an advanced stage, the patient may feel pain even at rest, which has become a serious disruption to life. At this point, the patient may be 70 years old, and if joint replacement is still not performed, the joint wear will become more and more severe, and eventually the joint will become deformed and stiff, and the patient will be confined to a wheelchair. In the beginning, only one side of the joint may need to be replaced, but in the later stages, both joints will be worn out more severely and may require treatment.