The present invention relates to a spacer implant (I) for the temporary replacement of a knee prosthesis, said implant (I) having a femoral condyle (1) and a tibial plateau (2), the lower surface (7) of the femoral condyle (1) resting on the upper surface (8) of the tibial plateau (2), the lower surface (7) of the femoral condyle (1) having a convex shape while the upper surface (8) of the tibial plateau (2) has a concave shape, a stud (9) being supported by the tibial plateau (2) and penetrating into a receiving means (17) provided on the femoral condyle (1), the femoral condyle (1) comprising two flanges (12, 13) having different sizes and being joined together via a base (7) traversed by a notch (17) forming the receiving means, the shorter flange (13) consisting of two elements (15) referred to as condyles, which are spaced apart from one another by the extension of the notch (17), and a stabilizing bar (16) joining the two condyles (15) together at the free end of said flange (13).
