Patient-Reported Metal Allergy: A Risk Factor for Poor Outcomes After Total Joint Arthroplasty?

Background Metal sensitivity after total joint arthroplasty has been of increased concern, but the impact of a patient-reported metal allergy on clinical outcomes has not been investigated. The purpose of this study was to report the incidence and impact of patient-reported metal allergy after total knee arthroplasty (TKA) and total hip arthroplasty (THA). Methods This was a retrospective, institutional review board–approved investigation of patients undergoing a primary, elective total joint arthroplasty between 2009 and 2011. All patients completed a preoperative questionnaire asking about drug and environmental allergies. In January 2010, a specific question was added regarding the presence of a metal allergy. University of California at Los Angeles Activity, Short Form 12 (SF-12), Modified Harris Hip, and Knee Society scores were collected preoperatively and at most recent follow-up. Overall cohorts of metal allergy and nonmetal allergy patients were compared, and a 1:2 matching analysis was also performed. Results Nine hundred six primary THAs and 589 primary TKAs were included. The incidence of patient-reported metal allergy was 1.7% before January 2010 and 4.0% after (overall 2.3% of THAs and 4.1% of TKAs); 97.8% of metal allergy patients were female. After TKA, postoperative Knee Society Function, Symptoms, Satisfaction, and Expectation scores were all decreased in the metal allergy cohort (P <.001-.002). After THA, metal allergy patients had a decreased postoperative SF-12 Mental Component Score and less incremental improvement in their SF-12 Mental Component Score vs the nonmetal allergy cohort (P <.0001 and P =.001, respectively). Conclusion Patient-reported metal allergy is associated with decreased functional outcomes after TKA and decreased mental health scores after THA.