a composition having a hydrogel bearing side of a biostable polymer network , wherein the biostable polymer network comprises a first gradient of the biostable polymer , which biostable polymer network decreases in concentration from the hydrogel bearing side to a bone interface surface ; and a second gradient of a biostable polyurethane network , which polyurethane network increases in concentration from the hydrogel bearing side to the bone interface surface , the bone interface surface useful for an orthopedic implant .