A tibial prosthesis assembly can comprise a tibial tray and a tibial insert. The tibial tray can have an inferior bone engaging surface, a superior surface, and a first retaining feature. The tibial insert can have an inferior tray engaging surface, a superior bearing surface, and a second retaining feature. The first and second retaining features can cooperate to inhibit substantial lift-off of the tibial insert away from the superior surface of the tibial tray while permitting a predetermined amount of rotation of the tibial insert around the superior surface in an assembled position.
