In typical knee repair or replacement surgery, a femoral implant includes a pair of convex condylar surfaces that can slide within corresponding concave bearing indentations on a tibial bearing surface. The tibial bearing surface is disposed on a proximal side of a tibial platform. A stem can extend distally from the tibial platform, and can attach to a cut proximal end of the tibia. A tibial augment can attach to the distal side of the tibial platform, and can reduce or eliminate a lateral overhang of the tibial platform with respect to the cut proximal end of the tibia. The tibial augment may have a tapered periphery. The taper may extend inward in a distal direction. The taper may vary along the periphery of the tibial augment, so that at least a portion of a medial taper is different from at least a portion of a lateral taper.