The present invention relates to an implant for flexibly linking a first vertebra to a second vertebra of a spine of a patient, comprising a deformable portion (12) for interconnection to the first vertebra and the second vertebra, the deformable portion (12) including interior sidewalls (56) around an interior region (24), the interior sidewalls (56) including a sloped interior surface (54) oriented at an angle (θ), said angle (θ) less than about 90 degrees relative to a plane aligned with a posterior side of the deformable portion (12) wherein when implanted posteriorly in the patient, the deformable portion (12) allows controlled bending motion while limiting sagittal translation of the first vertebra relative to the second vertebra with lengthening and shortening of the deformable portion (12).
