One concern about ceramic heads is that they have been known to break or fracture in the past. Newer ceramics and production protocols have significantly lowered this possibility. This combination places two extremely smooth surfaces in contact with one another, and this can result in significantly less wear and wear debris. In addition, ceramic is biologically inert and its wear debris may be less harmful than wear debris from other surfaces. This combination has been used in the past and has shown promising results.
Metal is harder than plastic.
The hard surface of metal theoretically leads to less wear. Currently studies are underway to evaluate its efficacy. Finally, modifications on the traditional polyethylene, highly cross-linked polyethylene have been developed in order to decrease the amount of wear in hip replacements. In laboratory tests, highly cross-linked polyethylene has been shown to have significantly less wear than traditional polyethylene. Advocates of highly cross-linked polyethylene feel that this technique is a less drastic departure from the traditional hip replacement.