Prevalence of allergic reactions to implant materials in total hip and knee arthroplasty

Introduction: Several case reports have been published on allergic reactions like eczema, urticaria, persistent swelling, sterile osteomyelitis or aseptic implant loosening in the context of orthopaedic implants. There is, however, a lack of data concerning incidence or prevalence of allergies in this special group of patients. The aim of this study was to analyse a consecutive series of patients with a total hip or knee arthroplasty to gain information about prevalence of allergic reactions to constituents of the alloys or bone cement. Material and Method: Between February and September 2005, a consecutive series of 300 patients after total hip (THA) or total knee (TKA) arthoplasty were interviewed during regular follow-up using the standardised questionnaire of the working group 20 Implant and Allergy of the DGOOC with respect to allergies, especially to different metals or constituents of bone cement. In this study 100 males and 200 females with 214 THA and 86 TKA were included. The mean follow-up time was 33.3 months (min: 3, max: 174). Results: Different allergies were found in 39 patients. In 12 cases (4%) allergic reactions against nickel, in 4 cases (1.3 %) against cobalt, in 2 cases (0.7 %) against chromium and in 2 cases (0.7 %) against benzoyl peroxide were detected by means of epicutaneous testing. One patient each suffering from a nickel allergy showed signs of osteolysis or recurrent effusion after THA with a metal-on-metal bearing. One patient each suffering from recurrent effusion or eczemafolllowing TKA showed allergic reactions to benzoyl peroxide. In all the other patients with allergies to the alloy constituents, the follow-up was uneventful. Conclusion: The prevalence of allergic reactions in an unselected group of orthopaedic patients is significantly lower in comparison to that in dermatological studies. Most patients suffering from allergies tolerated the implant uneventfully. Further studies are needed to identify those groups of patients with allergies who may not tolerate the implant in order to provide better care or use special implants.