Hypersensitivity: “Doc, Am I Allergic to My Implant?”

There is controversy regarding the clinical significance of metal hypersensitivity in total knee arthroplasty (TKA). Given the current state of the art, metal hypersensitivity, if it exists at all, is a diagnosis of exclusion. Clinical presentation may involve a cutaneous response, but current diagnostic methods do not have robust clinical validation and should be used with caution. The two most commonly used tests include cutaneous patch testing and in vitro lymphocyte transformation testing. Initially, conservative management is indicated and other more common causes of a symptomatic total knee replacement should be fully explored. In rare cases, device removal may be undertaken but this should be considered a last resort. Pre-operative testing prior to a primary total joint replacement may be helpful when there′s a patient-reported history of intolerance to jewelry or of an allergic reaction to a prior metal implant, but routine lab screening is not supported by the literature.