tibial post which can occur in cruciate substituting designs application_number US 201615351288 A description fig2 a through 2c illustrate one embodiment of the invention fig2 a shows the configuration in extension fig2 b shows the system at 90 degrees flexion and fig2 c illustrates flexion of 120 degrees or more in addition to a conventionally placed cam at 101 two additional points of cam action are preferably provided in particular a feature at 201 acts to prevent translation from extension into the initiation of the flexion feature 201 preferably disengages as conventional cam 101 is engaged as the knee follows through a range of motion to 90 u00b0 of flexion and beyond cam 101 disengages and feature 202 engages if necessary to prevent dislocation of the component in fig2 b the cam which is usually present at 101 is engaging the tibial post cam 201 has disengaged and cam 202 has not yet engaged but is available for engagement on further flexion in fig2 c cam 202 is now engaged the post in the presence of additional flexion cam 101 can now disengage cam 201 had disengaged earlier fig2 d illustrates the alternative use of interconnected cams with physically separate contact points in fig2 a through 4 the features depicted to provide the various stages of cam pivoting function are depicted as bars which cross the intercondylar recess or box portion of a cruciate substituting design knee however although the terms u201c cam u201d or u201c bar u201d are used to reference the stages of cam action it should be understood that the responsible structures may be.