The Authors, taking into account the fact that hip prosthetic implant mobilization frequently occurs due to excessive stress exerted on bone-prosthesis interface, suggest using prosthesis having stress-breakers, capable in reducing the loads exerted on the implant. There are some hip prosthesis in design which have a descharge force system in the cotyloid, in the neck and in the prosthetic stem. Some technical problems are not yet solved, expecially concerning the wear and tear, the friction and the lubrication of the stress-breakers.
