An intervertebral prosthetic disc for replacing a damaged natural disc includes upper and lower vertebral body engaging surfaces, an exterior wall and one or more generally vertically oriented bone channels of limited cross-sectional area to allow bone to form and fuse into continuous or discontinuous struts between the bodies. The stiffness of the disc, while supporting the bodies, allows the distance therebetween to narrow sufficiently when subjected to a predetermined load such as the patient standing, walking, etc., to transfer sufficient energy to the bone struts to create one or more nonunion joints or pseudoarthrosis at locations along the struts. The disc includes stops to limit the movement thereof to an amount sustainable by the disc without resulting in fatigue failure.