Knee replacement age is usually for the elderly, mostly around 60 to 75 years old. This is because the health conditions, compliance, longevity and post-operative functional exercises are more appropriate in all aspects for this age group. However, with the advancement of science and technology, the development of surgical materials, as well as doctors’ deeper knowledge of the disease, there is actually no strict limitation on the age requirement for knee replacement. 1. For example, total knee replacement, mostly for rheumatoid diseases, can be performed around the age of 30. Unicondylar replacement, on the other hand, is mostly used for osteoarthritis and is generally recommended by doctors for people over the age of 50. 2. Because the life span of the joint is relatively limited, if the age is around 50 years old, during the life span of the joint, the patient’s activity will also be significantly reduced, so in the joint replacement, usually choose to be a little older. 3. However, there is no absolute limit to the age of the patient, and it is more important to choose the treatment means and methods according to the degree of the patient’s disease. Knee replacement can relieve knee pain and improve knee function. It provides long-term stability. It is suitable for knee diseases that are ineffective with conservative treatment, but the specific treatment needs to be based on the doctor’s judgment of the patient’s condition.