Many people think that having a knee replacement means removing the entire knee joint and replacing it with a stainless steel one. They think it is a big operation and are filled with fear and anxiety. In fact, the knee replacement that I currently perform is a surface knee replacement. Various types of arthritis in the knee joint cause cartilage damage and subchondral bone lesions in the knee joint. This is a procedure that completely removes the cause of the disease. Previously, knee replacements were considered major surgeries with high surgical risks. However, with advances in surgical techniques and improvements in surgical equipment, surface knee replacement is no longer considered major surgery, but only moderate compared to some spinal orthopedic and tumor removal surgeries. Even so, I have always been very strict in my knowledge of the indications for knee surface replacement surgery. Indications for surface knee replacement. That is, if a patient with osteoarthritis or rheumatoid arthritis has a condition that meets all six of the following criteria, the patient should have a surface knee replacement. These six conditions are: 1. The pain, swelling, and weakness of the knee joints in the knee joints, such as going up and down stairs, have affected the daily life and necessary activities, and the treatment with Chinese and Western medicines has been ineffective. 2, the knee joint has “O” leg or “X” leg, that is, the knee inversion or knee valgus and other deformation changes. 3. Narrowing of the medial or lateral joint space of the knee joint. 4. Restriction of knee flexion and extension. The angle of flexion or extension of the knee has begun to affect daily life and work. 5. Severe bone formation and osteochondral destruction are visible on MRI (magnetic resonance imaging) or x-ray. 6. Age is 55 years or older.