Hypersensitivity to implant debris

Abstract

Total Joint Replacements (TJR) have been extremely successful over the past 50 years, restoring mobility and function to millions of people each year. However, over time these implants need replacing for a number of reasons, such as infection or increasing immune reactivity to implant debris. All implant metals degrade in vivo, and the released products biologically interact locally and systemically. Local and/or systemic immune reactivity to implant debris may become excessive, specifically to one or more of the materials (metals) used in the implant alloys. When this excessive reactivity to implant debris involves the adaptive immune system where lymphocytes respond to specific stimuli it can be characterized as a sensitivity or hypersensitivity response. Dermal hypersensitivity reactions to metals (such as Nickel) are common and affect approximately 10-15% of the population in USA and Europe. In its extreme form, metal sensitivity exists as a relatively rare complication in only a few highly susceptible patients with joint replacements (i.e., less than 1% of joint replacement recipients). However, the role of implant-related metal sensitivity in implant performance is likely underreported due to the scarcity of diagnostic testing. The person-dependent mechanism(s) by which metal sensitivity occurs in some people and not others has not been completely explored with current hypersensitivity testing techniques. This issue is becoming increasing popular due to recent failures of metal-on-metal hips and increasing numbers of joint replacement procedures, worldwide. Better materials and availability of appropriate immunologic testing (e.g., LTT) will likely enhance future assessment of patients susceptible to hypersensitivity responses.