Disposable modular spacer device (1) of the knee joint, comprising a tibial element (2, 2 ', 2' '), adapted to be immobilized at one end of the tibial bone in the vicinity of the knee joint, said tibial element (2, 2 ', 2' ') comprising a lower surface (7) and an upper surface (16, 16', 16 '') provided with a radius of curvature R2, and a femoral element (4, 4 ', 4' '), said femoral element (4, 4', 4 '') comprising an inner surface (14), adapted to be immobilized at one end of the femoral bone in the knee joint, and an outer convex surface (15, 15 ', 15' '), provided with a radius of curvature R1 and adapted to come into contact with said upper surface (16, 16', 16 '') of said tibial element (2, 2 ', 2' '), so that said tibial element (2, 2', 2 '') and said femoral element (4, 4 ', 4' ') have several dimensions or sizes, characterized in that said tibi element al (2, 2 ', 2' ') is configured to fit with any size of said femoral element (4, 4', 4 '') in order to adapt the dimensions of said modular spacer device (1) with the dimensions of the bone ends to which it should connect.Dispositivo espaciador modular desechable (1) de la articulación de una rodilla, que comprende un elemento tibial (2, 2', 2''), adaptado para quedar inmovilizado en un extremo del hueso tibial en las proximidades de la articulación de la rodilla, comprendiendo dicho elemento tibial (2, 2', 2'') una superficie inferior (7) y una superficie superior (16, 16', 16'') provista de un radio de curvatura R2, y un elemento femoral (4, 4', 4''), comprendiendo dicho elemento femoral (4, 4', 4'') una superficie interior (14), adaptada para quedar inmovilizada en un extremo del hueso femoral en la articulación de la rodilla, y una superficie convexa exterior (15, 15', 15''), provista de un radio de curvatura R1 y adaptada para entrar en contacto con dicha superficie superior (16, 16', 16'') de dicho elemento tibial (2, 2', 2''), de manera que dicho elemento tibial (2, 2', 2'') y dicho elemento femoral (4,
