Total knee replacement is nowadays a surgical technique that has reached maturity and is used as frequently as total hip replacement. It is mainly aimed at patients suffering from knee osteoarthrosis when it becomes invalidating and painful and does not respond anymore to medical conservative treatment and physiotherapy. Long term results are excellent in patients aged over 70 years old. They are still amenable to improvement in young patients who are more active and who put under stress their implants in a longer and more intense way. Infection, loosening and malpositioning of the implants are the most common complications.