| abstract |
An elongated, pillow shaped prosthetic spinal disc nucleus body (10) for implantation into a human intervertebral spinal disc (32), made of a hydrogel core (12) and a flexible constraining jacket (14) surrounding the hydrogel material core (12) that permits the hydrogel core (12) to expand and contract. The hydrogel core (12) has a length approximating the sagittal diameter of a nucleus of the human disc, a width less than the length, and a height less than the length or width. The hydrogel core will expand (See fig. I) and contract in a desired fashion as it imbibes and expels fluids in response to various loads placed upon the spinal tract. The constraining jacket (14) is porous to allow fluids to pass through to the hydrogel core (12), but prevents the hydrogel (12) from escaping, thus fostering the natural physiology of the human invertebral disc. By implanting two prosthetic spinal disc nucleus bodies (10) side-by-side into a damaged disc (32) of a human spine, both height and motion can be maintained. |