AND THE ANSWER IS . . . 1 Discussion In the early days of artificial hip surgery, the femoral head prosthesis and usually the receptacle cup were made of stainless steel, subject to wear and tear with release of metallic components into the joint. As a result, immune reactions to metallic components developed in some patients and were thought to play a role in loosening of the joint. Although systemic adverse effects have been blamed by some patients and investigators on such immune reactions, there is no convincing evidence that pathogenic IgE-mediated responses, including asthma were a result. Indeed, the immune responses appear to be predominantly cell-mediated. Over succeeding years this "metal to metal" approach was replaced by various modifications, particularly use of plastics in the receptacle cup instead of metal. Ceramics have also been used. As a result, there was less evidence of immune reactions to metallic components and a lower incidence of loosening. However, with continued use, the wear and tear effects on the plastic led to release of very small fragments of the plastic with resultant local irritation in some cases. Therefore, a metal to metal approach is now again being used in some centers. However, the current metal parts made of titanium, chromium and nickel appear to be less susceptible to wear-induced liberation of microscopic metal constituents that can induce immune reactions. Reference Br J Dermatol. 2003;148:1089-93 Please tell us what you think of this site. © Copyright 1997-2009 American Academy of Allergy, Asthma & Immunology All rights reserved