An arthroplasty spinal prosthesis with first and second vertebra contacting members that are configured for engaging opposing vertebrae An articulation is supportively associated with the contacting members to allow relative pivotal and translational motion therebetween over anterior-posterior and lateral pivotal axes, and over anterior-posterior and lateral translational axes. This motion allows the opposing vertebrae to pivot and translate with respect to each other. The articulation is configured to permit translational movement substantially uncoupled from the pivoting movement.