Inclusion Criteria:  Signed patient informed consent Implantation of a GEMINI SL Fixed Bearing PS knee prosthesis Age between 18 and 80 years  Exclusion Criteria:  Body Mass Index (BMI) > 40 kg/m² Foreseeable life expectancy under 5 years Comorbidities and known medical circumstances which would affect the clinical or functional outcome after implantation of the knee prosthesis (e.g. neurological or musculoskeletal diseases) at the time of implantation Patient who is mentally not able to understand the study and the study conduct Patients who will be foreseeable non-compliant to the planned routine interventions and study related follow-ups Prisoner Pregnant women