Rehydration and restoration of intervertebral discs with polyelectrolytes

A method for bulking up an intervertebral disc having a nucleus pulposus and an annulus fibrosis, using one or more polyelectrolyte materials, comprising:

• mixing the polyelectrolyte materials and an additive with a non-aqueous fluid to make the polyelectrolyte materials and the additive flowable, wherein the polyelectrolyte materials are not more than about 15% cross-linked, thereby having a low gel strength, and are capable of attracting an amount of fluid at least about ten times the weight of the polyelectrolyte materials in their dry form under atmospheric pressure, wherein polymer chains comprising the polyelectrolyte materials are cross-linked after polymerization of the chains by reaction with a cross-linking agent;
• introducing the polyelectrolyte materials and the additive into the intervertebral disc space having an intact and competent annulus fibrosis without removing nucleus pulposus or annulus fibrosis material;
• and
• introducing a cross-linking agent into the intervertebral disc space to react with the polyelectrolyte materials and the additive form an aggregate cross-linked material within the intervertebral disc space comprising the polyelectrolyte materials and the additive cross-linked by the cross-linking agent, thereby accomplishing at least one of an increase in the disc height, an increase in the disc volume, and an increase in the intra-discal pressure.