The invention relates to a knee joint prosthesis comprising a femoral component (1) and a tibial component (2), each having a front face constituting the joint and a rear face (4) facing the bone, and a polyethylene (PE) liner (3). In order to allow the knee joint prosthesis to be implanted without metal and without cement, the femoral component (1) and the tibial component (2) consist of a full ceramic material and both components (1, 2) have integrated porous osseointegrative rear faces (4) facing the bone.