A selected augment, shown as a tibial augment, is secured at an augmentation location on a prosthetic implant component, shown as a tibial implant component, by a securing element assembled with the body of the augment for displacement relative to the augment body to selectively engage an abutment located on a depending structure of the implant component, adjacent the augmentation location, so as to establish a securing force between the securing element and the depending structure for urging the augment against the implant component, and thereby secure the augment to the implant component at the augmentation location. In the tibial augment, a distal surface includes surface portions extending in anterior-posterior directions and oriented essentially normal to medial-lateral directions.