A prosthetic device for lateral insertion into an intervertebral space is provided. The device includes a first component for engaging a first vertebral body, a second component for engaging a second vertebral body, and an articulation member positioned between the first and second components. The first and second components each have a length that extends upon cortical bone of opposing sides of an apophyseal ring of the corresponding vertebral body and a width that is smaller than the length. A ratio of length to width for each of the first and second components can be in the range of 1.3:1 to 1.7:1.