The goal of this scientific study is to determine whether there are differences in early migration and prosthesis-near bone density when a standard knee prosthesis is fixed with Refobacin Bone Cement R or with Refobacin Plus Bone Cement. Migration will be evaluated with RSA and bone density around the prosthesis with DEXA. The study will be successful if the prosthesis is fixed and remains in place throughout the entire period of the study, that is, that there is no increasing migration as measured by RSA. The cement type that ensures the largest number of solidly fixed prostheses during the two-year evaluation period will be "the best".