J Allergy Clin Immunol Pract 2021 Mar 17. Epub 2021 Mar 17.
Associate Professor, Division of Environmental & Occupational Health Sciences, Department of Medicine, National Jewish Health, 1400 Jackson St, Denver, CO 80206; Division of Environmental & Occupational Health, University of Colorado School of Medicine, School of Public Health, 13001 E 17th Place, Mail Stop B119, Aurora, CO 80045. Electronic address:
Background: Over 90% of 1 million yearly US joint replacements are highly successful. Nonetheless, 10% do poorly, attributed to infection or mechanical issues. Many implant components are sensitizers, and sensitization could also contribute to implant failure.
Objective: Determine the prevalence of implant sensitization in joint failure patients, their clinical characteristics, and implant revision outcomes. We hypothesized that sensitized patients should improve when revised with non-'allergenic' materials.
Methods: We prospectively enrolled n=105 joint failure patients referred by their orthopedic surgeon who had already excluded infection or mechanical causes. Patients provided informed consent, completed a history & physical exam, patch testing to metals and bone cement, and a Nickel lymphocyte proliferation test (Ni-LPT). A study coordinator was able to contact 64% (n=67) 9-12 months later to evaluate outcomes.
Results: 59% were sensitized to an implant component: 32% to metal and 37% to bone cement. The Ni-LPT was 60% sensitive and 96% specific in diagnosing nickel sensitization. Most sensitized subjects reported no or uncertain histories of reactions to the specific material(s). Implant sensitized patients were younger, reported previous eczema, joint itching, and implant loosening. 9-12 months later, most patients with a revised implant ('revised') described significant improvement (16/22 revised for sensitization, p=0.0003, vs. 9/13 revised without sensitization, p=0.047) compared to patients without implant revision). All revised patients with sensitization used components to which they were not sensitized. Pain (p=0.001), swelling (p=0.035), and instability (p=0.006) were significantly reduced in the revised sensitized group.
Conclusions: Sensitization to implant components is an important cause of unexplained joint replacement failure. Joint revisions based on sensitization information resulted in significant improvements.