This application relates to a device for enlarging a stent of a joint, in particular to an enlarged tibia prosthesis knee joint, which comprises a sleeve (10) (11) which surrounds the channel which extends through the sleeve (1 0).The sleeve (10) is formed by a porous material (2) for the ingrowth of the bone material, comprising a sleeve (10) inside an outer Face (14) and (15).The sleeve (10) also includes a Wall (3) surrounding the channel (11), while the Wall (3) Made of Solid material and the Wall (3) forming a sandwich structure with Porous material (2), where (3) form a Partition wall between the Inner Face (14) and the Outer Face (15).With this measure, the partition Wall (3) Stop the entry of any Cement through the sleeve (10) from the inside to the outside (14) and (15). The Porous material (2) by the Outer Face (15) will remain free of Cement, being reliably preserved in their capacity to promote the ingrowth of bone material.Enlargement devices are preferably provided as a set that has different sizes and funds straight or staggered to enhance its Versatility and preserve the natural Bone material.La presente solicitud se refiere a un dispositivo de agrandamiento para una endoprótesis de articulación, en particular un agrandamiento de tibia para una endoprótesis de articulación de rodilla, que comprende un manguito (10) que circunda el canal (11) que se extiende a través del manguito (10). El manguito (10) está formado por un material poroso (2) para el crecimiento hacia adentro del material óseo, comprendiendo el manguito (10) una cara interior (14) y una cara exterior (15). El manguito (10) comprende además una pared (3) que circunda el canal (11), estando la pared (3) constituida de material sólido y formando la pared (3) una estructura sándwich con el material poroso (2), en donde la pared (3) forma una mampara entre la cara interior (14) y la cara exterior (15). Con esta medida, la pared de mampara (3) detendrá el ingreso de cualquier cemento a travé
