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.

1 . (canceled) 
     
     
         2 . An orthopedic implant comprising a hydrogel and having a first surface and a second surface, the hydrogel having an equilibrium water content of at least 15% and a modulus of at least about 1 MPa, and the first surface having a coefficient of friction in aqueous solution of less than 0.2. 
     
     
         3 . The orthopedic implant of  claim 2 , wherein the orthopedic implant is at least 1 mm in thickness. 
     
     
         4 . The orthopedic implant of  claim 2 , wherein the first and second surfaces are different. 
     
     
         5 . The orthopedic implant of  claim 2 , wherein the implant is configured for cartilage replacement in a joint. 
     
     
         6 . The orthopedic implant of  claim 5 , wherein the joint is selected from a hip, a shoulder, a knee, an elbow, a finger, a joint of the hand and a joint of the foot. 
     
     
         7 . The orthopedic implant of  claim 2 , wherein the implant is a cartilage replacement implant and wherein the first surface is a bearing surface that is adapted to articulate with an additional bearing surface upon implantation. 
     
     
         8 . The orthopedic implant of  claim 7 , wherein the additional bearing surface is a natural cartilage surface or an implanted device surface. 
     
     
         9 . The orthopedic implant of  claim 7 , wherein the second surface is adapted for anchoring the implant to bone. 
     
     
         10 . The orthopedic implant of  claim 7 , wherein the second surface is adapted for anchoring to an acetabular cavity, a tibial plateau, an inner aspect of a glenoid, a femoral head, or a distal femur. 
     
     
         11 . The orthopedic implant of  claim 7 , wherein the first surface has a primarily concave shape and the second surface has a primarily convex shape. 
     
     
         12 . The orthopedic implant of  claim 11 , wherein the primarily convex shape of the second surface is adapted to mate with an acetabular cavity or an inner aspect of a glenoid. 
     
     
         13 . The orthopedic implant of  claim 7 , wherein the first surface has a primarily convex shape and the second surface has a primarily concave shape. 
     
     
         14 . The orthopedic implant of  claim 13 , wherein the primarily concave shape of the second surface is adapted to mate with a femoral head or distal femur. 
     
     
         15 . The orthopedic implant of  claim 9 , wherein the second surface is adapted to interact with adjacent bone to allow for anchoring via osteointegration over time. 
     
     
         16 . The orthopedic implant of  claim 2 , wherein the hydrogel has a permeability coefficient ranging from 1 e −18  to 1 e −12  m 4 /Nsec. 
     
     
         17 . The orthopedic implant of  claim 2 , wherein the hydrogel is immersed in an aqueous salt solution having a neutral pH. 
     
     
         18 . The orthopedic implant of  claim 2 , wherein the hydrogel is negatively charged at neutral pH. 
     
     
         19 . The orthopedic implant of  claim 2 , wherein the hydrogel comprises sulfonic acid groups. 
     
     
         20 . An arthroplasty procedure, wherein an orthopedic implant in accordance with  claim 2  is implanted in a joint. 
     
     
         21 . The method of  claim 20 , wherein the orthopedic implant is implanted on one side of the joint in a hemi-arthroplasty procedure. 
     
     
         22 . The method of  claim 20 , wherein the orthopedic implant is implanted on both sides of the joint in total arthroplasty procedure. 
     
     
         23 . The method of  claim 22 , wherein the joint is selected from a hip, knee, shoulder, elbow, a finger, a joint of the hand, or a joint of the foot.