Knee replacement The knee prosthesis is the replacement of the superficial component of the joint. That which is removed is only the final part of the bone and is performed with the special masks, designed by engineers, that are applied on the bone surfaces. In this way the squares are made by cutting, only and exclusively, the damaged portion of the bone. The final result will be to encapsulate, replacing it, the joint surface with two metal components, for what concerns the femur, which will float on a plastic component (ultra high molecular weight polyethylene), at the level of th