Hydrogel Intervertebral Disc Nucleus with Diminished Lateral Bulging

摘要

A prosthetic nucleus (10) for a vertebral disc is made of a hydrogel material. The hydrogel prosthetic nucleus has a shape generally conforming to the natural nucleus pulposus, and it exhibits diminished lateral bulging under high compressive loads. The hydrogel has a water content of from 30% to 90% and has a compressive strength of 4NM-2 or greater. When the hydrogel material is dehydrated, it has a dimension of less than half ofthat of the hydrated hydrogel nucleus. The prosthetic nucleus may be formed of two or more pieces of hydrogel material (42, 44) which pieces, when combined, have a shape generally conforming to the natural nucleus. The prosthetic nucleus may have a stiff posterior periphery (24) and/or a thickened anterior wall (28). IMAGE