Sensitization to Implant Components Is Associated with Joint Replacement Failure: Identification and Revision to Nonallergenic Hardware Improves Outcomes

BACKGROUND: Over 90% of one million annual US joint replacements are highly successful. Nonetheless, 10% do poorly owing to infection or mechanical issues. Many implant components are sensitizers, and sensitization could also contribute to implant failure. OBJECTIVE: To determine the prevalence of implant sensitization in joint failure patients, their clinical characteristics, and implant revision outcomes. We hypothesized that sensitized patients would improve when revised with nonallergenic materials. METHODS: We prospectively enrolled 105 joint failure patients referred by orthopedic surgeons who had already excluded infection or mechanical causes. Patients provided informed consent, completed a history and physical examination, patch testing to metals and bone cement, and a nickel lymphocyte proliferation test. A study coordinator was able to contact 64% of patients (n = 67) 9 to 12 months later to evaluate outcomes. RESULTS: A total of 59% were sensitized to an implant component: 32% to metal and 37% to bone cement. The nickel lymphocyte proliferation test was 60% sensitive and 96% specific in diagnosing nickel sensitization. Most sensitized subjects reported no or uncertain histories of reactions to a specific material. Implant sensitized patients were younger and reported previous eczema, joint itching, and implant loosening. By 9 to 12 months later, most patients with a revised implant (revised) described significant improvement (16 of 22 revised for sensitization [P = .0003] vs 9 of 13 revised without sensitization [P = .047]) compared with patients without implant revision). All revised patients with sensitization used components to which they were not sensitized. Pain (P = .001), swelling (P = .035), and instability (P = .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. (C) 2021 American Academy of Allergy, Asthma & ImmunologyY

Automated summary

The study found that 59% of joint failure patients were sensitized to implanted components, with a higher risk in younger patients, while most patients had no clear history of reactions to allergenic materials. Revisions using non-sensitizing materials for sensitized patients resulted in significant improvements in symptoms.