Robotic knee surgery makes it possible to adopt different alignment philosophies in total knee arthroplasty. The classical operation where the knee is placed in a neutral manner, the so called mechanical alignment, has been used for decades. The kinematical alignment has recently won popularity. With this technique the focus is to render the natural knee anatomy even if this means to end up with a varus or valgus position. In this study, the investigators will compare the mechanical alignment and kinematical alignment and test the patients clinically and with a special CT scan to see if this technique gives equal or better longevity of the implants.