An artificial vertebral joint for interposition between a superior vertebra and an inferior vertebra comprises a pair of bilateral joint subcomponents. Each joint subcomponent includes a superior component including a superior vertebra engaging surface and an inferior component including an inferior vertebra engaging surface. Each joint subcomponent further includes a spacer extending between the superior component and the inferior component. The spacer includes a first modulus of elasticity and a second modulus of elasticity. The first modulus transitions to the second modulus with a gradient change.