Augments systems and methods for attaching two or more augments to an underside (50) of a tibial baseplate (16) are disclosed. An augment system (100) can include a first augment (102) having a superior surface (106) and an inferior surface (108), the superior surface configured for attachment to the underside of the tibial baseplate. The augment system can include a second augment (104) having a superior surface (110) and an inferior surface (112), the superior surface configured for attachment to the inferior surface of the first augment. The first and second augments can be formed of different materials. One or more additional augments can be used with the first and second augments, and the augment system can be stacked on a resected surface of the tibia. In an example, the augment that directly contacts the resected surface of the tibia can be formed of a porous material, such as to facilitate bone growth.
