Abstract: By implanting two prosthetic disc capsules side-by-side into a damaged disc of a human spine, both height and motion, including front-to-back bending, can be maintained. Each prosthetic disc capsule has a bladder enclosing a fluid containing a therapeutic material that is slowly diffusible through a semi-permeable membrane of the bladder. The fluid filling the semi-permeable membrane preferably is an aqueous solution that has gel-like properties that afford a viscosity and velocity-shear behavior imitating the natural rheology of intradiscal nuclear tissue. Those properties are obtained when the aqueous solution is of a mucopolysaccharide such as hyaluronic acid or soldium hyaluronate.

Abstract: By implanting two prosthetic disc capsules side-by-side into a damaged disc of a human spine, both height and motion, including front-to-back bending, can be maintained. The prosthetic disc capsules have an outer layer of strong, inert fibers intermingled with a bioresorbable material which attracts tissue ingrowth, a bladder enveloped by the layer, and a thixotropic gel filling the bladder. The prosthetic disc capsules can be surgically implanted by (1) jacking apart the vertebrae adjacent a damaged disc, (2) forming a substantially sagital bore in the damaged disc near each of its lateral edges, and (3) inserting one of the capsules axially into each bore.