A prosthetic disc for insertion between adjacent vertebrae includes a core having upper and lower curved surfaces and upper and lower plates. At least one of the curved surfaces of the core is metallic, and in some embodiments the entire core is metallic. Each plate has an outer surface which engages a vertebra and a metallic inner curved surface which is shaped to slide over one of the curved surfaces of the core. In some embodiments, the center of rotation of the core is free to move relative to the upper and lower metallic plates. In some embodiments, one or more channels extend across one or both of the curved surfaces of the core for allowing passage of bodily fluid to promote lubrication between the core and at least one of the plates.