In the development of modern cemented total knee arthroplasty, the posterior stabilized knee prosthesis was designed to substitute for the function of the posterior cruciate ligament. Implant designs include the Insall Burstein posterior stabilized knee and the Legacy posterior stabilized knee. The primary feature of these prostheses is the femoral cam and tibial spine mechanism, which prevents posterior tibial subluxation and enhances knee kinematics. Another important feature is the relatively conforming round on round articular geometry that mitigates edge loading and reduces polyethylene damage. In concert, these features have produced a lineage of implants with unsurpassed clinical results, predictable kinematics and durability, which have been reproducible and well documented.