Patent ID: 7666225

Claim:
A spinal disc nucleus pulposus prosthesis comprising a hydrogel formed from a macromer and an amphiphilic comonomer, wherein the macromer has a poly(vinyl alcohol) (PVA) backbone having a molecular weight of about 100,000 to about 150,000, and pendant chains bearing crosslinkable groups in an amount of about 0.05 to 1.5 milliequivalents crosslinker per gram of backbone, wherein the comonomer is present at a concentration between about 40-60% by weight, and wherein the PVA backbone is modified with a hydrophobic modifier comprising acetaldehyde diethyl acetal (AADA) present in an amount of about 2.5 to 4.0 milliequivalents per gram (meq/g) of PVA.