The invention relates to a knee prosthesis (1) including a femoral part (2) connected to a tibial plate (3) by an intermediate meniscal plate (4) provided with an upper surface (5). The intermediate meniscal plate (4) and the tibial plate (3) are connected to each other by two planar joining surfaces, the tibial plate (3) including a central pivot pin (26) or at least one clipping/indexing finger (34, 35) which protrudes with respect to the tibial joining surface (11). The meniscal joining surface (12) of the meniscal plate (4) includes, in combination, a central hole (25) capable of engaging with the pivot pin (26) of the tibial plate in one case, and a locking recess (46, 47) capable of becoming embedded with the indexing finger (34, 35) of the tibial plate in the other one case, depending on whether the tibial plate comprises a pivot pin or an indexing finger.
