There are currently four subtypes of prosthesis being used in North America: composite, hydraulic, elastic, and mechanical discs. The type of disc chosen is up to the surgeon and his or her preferences.
A composite prosthesis is made of three parts, the two outer parts and the center that acts as a buffer, allowing the patient's replacement to act as a lumbar disc. The hydraulic prosthesis contain a gel-like core, which is dehydrated and made as small as possible before it is implanted into the spine. After implantation, it reconstitutes itself with the spinal fluid. The elastic discs work with two titanium plates with an rubber or silicone substance in the middle. Finally, the mechanical disc is more like the traditional joint prosthesis and is composed of metal-hinged plates or a ball and socket design.