a hydrogel - metal assembly is provided . an intervening polymer network is used to bond together a water - swollen hydrogel layer and a biocompatible surface - modified metallic layer . the hydrogel layer is a water - swollen hydrogel layer of at least two interpenetrating polymers . the surface of the biocompatible surface - modified metallic layer is surface - modified with an inorganic material . the intervening polymer network has been chemically grafted to the inorganic material of the biocompatible surface - modified metallic layer through bi - functional linker molecules . the intervening polymer network is further physically or chemically cross - linked with the polymers of the water - swollen hydrogel . the hydrogel - metal assembly can be adapted to form a medical device , medical implant , an artificial implant , an orthopedic implant , or at least as part of a joint . the hydrogel - metal assembly is attractive for use as such implants or devices due to its characteristics such as , for example , low coefficient of friction , impact - absorption capacity or strength , and / or biocompatibility .