Hydrogel arthroplasty device

Abstract

An arthroplasty device is provided having an interpenetrating polymer network (IPN) hydrogel that is strain-hardened by swelling and adapted to be held in place in a joint by conforming to a bone geometry. The strain-hardened IPN hydrogel is based on two different networks: (1) a non-silicone network of preformed hydrophilic non-ionic telechelic macromonomers chemically cross-linked by polymerization of its end-groups, and (2) a non-silicone network of ionizable monomers. The second network was polymerized and chemically cross-linked in the presence of the first network and has formed physical cross-links with the first network. Within the IPN, the degree of chemical cross-linking in the second network is less than in the first network. An aqueous salt solution (neutral pH) is used to ionize and swell the second network. The swelling of the second network is constrained by the first network resulting in an increase in effective physical cross-links within the IPN.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Patent Application 60 / 923,988 filed Apr. 17, 2007, which is incorporated herein by reference. This application is a continuation-in part of U.S. patent application Ser. No. 12 / 070,336, filed Feb. 15, 2008, which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to interpenetrating polymer network hydrogels. More particularly, the present invention relates to devices and materials useful for orthopaedic prostheses.BACKGROUND OF THE INVENTION[0003]With disease or damage, the normally smooth, lubricious cartilage covering joint surfaces progressively deteriorates, exposing bone and leading to arthritic pain that is exacerbated by activity and relieved by rest. Today, patients with osteoarthritis are faced with only one of two choices: either manage their pain medically, or undergo an effective but highly bone-sacrificing surgery. Medi...

AI Technical Summary

Benefits of technology

[0017]In still another example, the coefficient of friction of the bearing region of the strain-hardened interpenetrating polymer network hydrogel in an aqueous solution is less than 0.2. In still another example, one side of the device is modified with another polymeric material, other functional groups, or biomolecules using bifunctional crosslinkers. In one example, the biomolecules could be used to stimulate bone cell growth and / or adhesion. In yet another example, the device is comprised of stimulus-responsive polymeric materials that allow it to shrink or swell to conform to the convexity or concavity of an adjacent joint surface.

Problems solved by technology

However, if only one of the surfaces is damaged, then only one side can be capped, creating a cap-on-cartilage articulation.

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