The cruciate ligaments (and the intercondylar eminence of the tibia) should be removed when the knee is replaced. A mechanically unlinked prosthesis can be designed which will then be capable of restoring "cruciate" stability, i.e., anteroposterior stability of the tibia in the flexed knee. A knee replaced with such a prosthesis will only be stable if the prosthesis is inserted using the correct instruments and technique. Stability depends as much on precise surgical technique as it does on prosthetic design.