Implant assemblies, systems, and methods for replacing a knee joint may include a method of revising a knee joint prosthesis implanted in a knee of a patient to provide increased stability to the knee joint prosthesis by replacing a first tibial insert with a second tibial insert that provides more constraint that the first tibial insert. A knee joint prosthesis system and kit are also provided that may include a tibial baseplate component, a femoral component, and a tibial insert that is selectively interchangeable with other tibial inserts to provide varying levels of constraint and stability to the knee joint prosthesis.