FIG. 1 is a perspective view of a concave intervertebral disc prosthesis showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a side elevation thereof;

FIG. 5 is a side elevation of the side opposite that shown in FIG. 4;

FIG. 6 is an end elevation thereof;

FIG. 7 is an end elevation of the end opposite that shown in FIG. 6;

FIG. 8 is a perspective view of a modified embodiment of the design shown in FIGS. 1 through 7;

FIG. 9 is a top plan view thereof;

FIG. 10 is a bottom plan view thereof;

FIG. 11 is a side elevation thereof;

FIG. 12 is a side elevation of the side opposite that shown in FIG. 11;

FIG. 13 is an end elevation thereof; and,

FIG. 14 is an end elevation of the end opposite that shown in FIG. 13.