A device for augmenting a tibial stem for a human knee, the tibial stem is coupled to a distal side of a tibial platform (120), a proximal side of the tibial platform coupled to the articulation surface with a femoral component, the tibial platform from a medial side (124) and a lateral side (122), the device comprises: a tibial augmentation (100) configured to engage the tibial platform (120) near a distal side of the tibial platform, the tibial augmentation includes a medial side (106) for attachment to the medial side of the tibial platform, the medial side of the tibial augmentation has a conical part (118) medial on at least a part of its periphery that extends inward in a distal direction, and a lateral side (104) for attachment to the lateral side of the tibial platform, the lateral side of the tibial augmentation has a conical part (116) lateral on at least a part of its periphery extending inward in one direction distal n； wherein at least a portion of the medial conical part is different from at least a portion of the lateral conical part； and in which the medial conical part (118) is constant on the periphery of its medial side (106) of the tibial augmentation； and wherein the lateral conical part (116) is constant on the periphery of the lateral side (104) of the tibial augmentation.Un dispositivo para aumentar un vástago tibial para una rodilla humana, el vástago tibial se acopla a un lado distal de una plataforma (120) tibial, un lado proximal de la plataforma tibial acoplado a la superficie de articulación con un componente femoral, la plataforma tibial de un lado (124) medial y un lado (122) lateral, el dispositivo comprende: un aumento (100) tibial configurado para acoplarse a la plataforma (120) tibial próxima a un lado distal de la plataforma tibial, el aumento tibial incluye un lado (106) medial para unión al lado medial de la plataforma tibial, el lado medial del aumento tibial tiene una parte cónica (118) medial sobre por lo menos una parte de
