The invention relates to medicine, and specifically to traumatology and orthopaedics, and can be used for the endoprosthetic replacement of a knee joint. The knee joint endoprosthesis includes a femoral component, a tibial component with a supporting stem enabling fixation in the epiphyseal cartilage of a shin bone, and a detachable polymer insert. The insert has a congruent surface for sliding contact with the joint surface of the femoral component and a rotating tapered stem for sliding contact with a tapered cavity in the supporting stem of the tibial component. Open pore channels, measuring between 0.1 and 200 microns, are provided on the surface of the insert, said surface being in contact with the joint surface of the femoral component, and cover between 5 and 25% of the sliding surface area. The technical result achieved by implementation of the claimed knee joint endoprosthesis, consists of increasing the quantity of synovial fluid between rubbing surfaces, which makes it possible to lower the coefficient of friction, to increase the wear resistance of the rubbing surfaces, and in addition, to reduce the quantity of wear particles in the area of friction, which reduces the wear rate of the polymer insert, reduces the likelihood of osteolysis developing and increases the service life of the endoprosthesis.