A tibial anchoring assembly comprising a tibial tray and an anchor. The tibial tray comprises an upper surface for engagement with a femoral component and a lower surface for engagement with a tibia bone. The lower surface defines at least one retaining aperture. The anchor is adapted to compressively couple the tibial tray to the tibia bone. The anchor comprises a longitudinally extending base, a top section coupled to the base and having a shape to be received into the retaining aperture of the tibial tray, and a flexible blade member protruding from the base. The flexible blade member is adapted to be flexed in tension while being inserted into the tibia bone, thereby exerting a compressive force between the tibial tray and the tibia bone. A deforming fixture may be used to shape the flexible blade member. Methods of affixing an implant to a bone structure are also provided.