This prosthesis (1) includes two plates (2, 3) and an intermediate damping core(4) placed between both of these plates (2, 3), this core (4) comprising a first shell (6) and a flexible element (11) placed between this first shell (6) and a part (5 2) for receiving this core, said first shell (6) and said first receiving part (5 2) comprising means (18, 26) for guiding their mutual movement for bringing them closer or moving them away from each other. According to the invention, -said receiving part (5 2) comprises a cavity (19) intended to snugly receive the flexible element (11), this cavity (19) being delimited by a first peripheral wall (18) and by a bottom wall, said first peripheral wall (18) having an external peripheral face and -said first shell (6) has a second peripheral wall (26) forming an internal face, this internal face, when said first shell (6) and the receiving part (5 2) are in their assembling condition, coming into close proximity to said external peripheral face and being able to slide along the latter.
