acet prosthesis shown in FIGS. 11 and 12; [0042]FIG. 15 is a cranial view of the alternative implanted left superior facet prosthesis shown in FIGS. 11 and 12; [0043]FIG. 16 is a perspective view of the alternative left superior facet prosthesis shown in FIGS. 11 and 12; [0044]FIG. 17 is a perspective view of an alternate bearing surface for the superior facet prosthesis shown in FIG. 16; [0045]FI