US Patent 7282165 Wear resistant hydrogel for bearing applications

A wear resistant hydrogel for use as a prosthetic implant, such as for cartilage, is made by forming a solution of polyvinyl alcohol in a solvent of DMSO/water. The solution is placed in a mold and is gelated by cycling the mold in a freeze-thaw cycle at a temperature at or below 4° C. for a period of 2 to 24 hours. The hydrogel so formed is washed in a saline solution, including potassium carbonate. The hydrogel is then dehydrated to 20 to 70% water content and thereafter irradiated with Gamma radiation. The surface of the hydrogel is then cross-linked using a boric acid solution preferably between 2.5 and 5% for about 1 minute. The hydrogel is then rinsed and sterilized.