In a tibial component comprising an anchor portion for being fixed in bone and a tray for a sliding plate of polyethylene, the tibial component cooperating with a femoral component which rests on the sliding plate by curved articulation surfaces, it is provided that the sliding plate (1) has an attachment (2) which extends inside the anchor portion (5) of the tibial plateau component (4) and which, distally of the tibial plateau component, is non-rotatably joined to the anchor portion (5) by positive fit.