The present invention comprises a polymer and/or polymer composite based sleeve to be fitted between an extended body, such the neck, trunnion, and/or stem of a hip implant, and a receiving body, such as a femoral head in a hip implant, that reduces wear, decreases toxic material from wear debris, enhances the mechanical connection of the extension and receiving body, reduces or eliminates impingement with receiving body, delocalize stress concentrations, and may also serve as a modifying junction between an extension and receiving body of unmatched size. The polymeric based sleeve presently disclosed comprises an inert and/or biologically favorable material which may be used in its virgin form or contain biocompatible additives. In order to best match patient and implant requirements, modifications may be made in the length, thickness, composition, as well as the presence of a taper, or lack thereof, in order to be compatible with existing devices.