MicroPort Orthopedics Inc. (MPO) plans to market the EVOLUTION® NitrX™ Non-Porous Keeled Tibia and EVOLUTION® NitrX™ CS/CR Non-Porous Femur with the EVOLUTION® Cruciate Sacrificing (CS) Tibial Insert globally, including in the European Union (EU). MPO is conducting this post market clinical follow-up (PMCF) study to evaluate the safety and effectiveness of the EVOLUTION® NitrX™ Non-Porous Keeled Tibia and EVOLUTION® NitrX™ CS/CR Non-Porous Femur. These components are used along with the EVOLUTION® Cruciate Sacrificing (CS) Tibial Insert components that is marketed in the European Union (EU). This type of data collection is required by regulatory authorities for all TKA devices that do not have medium to long-term clinical evidence available.