Implant the tibia of a prosthesis of the knee joint comprising a support plate (1), and a tibial base (2) and means for assembling and fixing the plate (1) on the base (2), comprising a rear stop (4) on the one - ci, adapted to immobilize a rim (5) the rear of the plate (1), a front flange (7) that - latter is able to clip into a form that is compatible (6) of the base (2), and the guide means are arranged two by two laterally on either side of the upper surface (172) of the base (2), open at least on the front of that - latter, and on either side of the lower surface (171) of the support plate (1), the said guide means (3, 13) being able to cooperate with one another during the sliding with a continuous contact of the support plate (1) on and against the base (2), and said compatible shape (6) being disposed at a given distance under the upper surface of contact (172) of the base (2), said front edge (7) of the support plate (1) being itself - same offset with respect to the lower surface (171) of the support plate (1) of the same distance in order to cooperate with the said shape compatible (6).
