The knee prosthesis system according to the invention may be used for revisionary or tumor prosthesis operations, and contains a tibial component provided with a stem and a femoral component provided with a stem and fitting to said tibial component. The point of the invention is that the tibial component (8) is provided with a knee cap (9) connected to the corresponding stem (7) and having two spherical segments (13, 14) at the two sides thereof. The femoral component (2) is provided with two ball-heads (4) to be fitted in said spherical segments (13, 14) of the knee cap (9) and to be connected to the corresponding stem (1). The ball-heads (4) are provided with inner holes receiving self locking conical pins (3) connected to the tibial stem (7). The system contains several ball-heads (4) having inner holes of different lengths and stems (1, 7) of different lengths, wherein the angle (β) between the conical pins (3) and the corresponding stem (1) is 120-150°. The height (h) of the front side of the knee cap is the half height of the ball-head, and the back side of the knee cap is provided with a cutout of about the quarter of the height of the ball head, in an angle (α) preferably 45°. There are inserts between the stems (1, 7) and the tibial/femoral components, for adjusting the lengths. ˙La présente invention concerne un système de prothèse du genou pouvant être utilisé pour des opérations de révision ou de prothèse tumorale. Ledit système contient un composant tibial pourvu dune tige et un composant fémoral pourvu dune tige et sinsérant dans ledit composant tibial. Le composant tibial (8) selon linvention est pourvu dune rotule (9) reliée à la tige (7) correspondante et possédant deux segments sphériques (13, 14) sur ses deux côtés. Ledit composant fémoral (2) est pourvu de deux têtes sphériques (4), devant être ajustées dans lesdits segments sphériques (13, 14) de la rotule (9) et être reliées à la tige (1) correspondante. Les têtes sphériques (4) sont pourvues d
