09-05-2025
Prepare Implant Patients for Potential Allergic Reactions
Individuals scheduled for total knee replacements and other implant surgeries had higher than average reactions to nickel and cobalt, which were the top causes of allergic reactions in posttransplant patients as well, according to data presented at the 2025 meeting of the American Contact Dermatitis Society.
The North American Contact Dermatitis Group (NACDG) has collected data on reactions to implants since 2016, Amber R. Atwater, MD, of Duke University Medical Center, Durham, North Carolina, and colleagues wrote in their abstract.
Although many patients receive implants every year, and concerns about implant-related reactions are ongoing, large population studies on implant-related hypersensitivity are limited, Atwater said in an interview.
She and her coauthors reviewed NACDG implant patch testing results from 2016 to 2022. The data included 128 adults who underwent preimplant patch testing, and the top three implant sites were the knee, hip, and heart (46.8%, 15.9%, and 9.5%, respectively). The postimplant study population included a total of 170 adults.
Nickel was tested at 5% and 2.5% concentrations, which accounted for the most common reactions (43% and 29.1%, respectively), followed by vanadium (14.3%), and cobalt (11%).
Reactions were assessed in four categories of dermatitis sites: 'None,' 'at implant site,' 'scattered,' and 'other' (45.3%, 29.8%, 14.9%, and 9.9%, respectively). Among the postimplant patients, 18 received a diagnosis of 'allergic contact dermatitis at the implant site due to implant.'
Overall, the results were not surprising, but two findings were particularly interesting, Atwater told Medscape Medical News .
First, patients who underwent preimplant testing had significantly higher nickel positivity than the standard NACDG patch-tested populations, she said. Patients are frequently referred for preimplant patch testing because of concerns about nickel allergy, and this allergy is often confirmed, Atwater said.
Second, 'approximately 10% of postimplant patients receive a final diagnosis of 'allergic contact dermatitis at implant site due to implant,'' said Atwater. This means that only about 1 in 10 patients who undergo postimplant patch testing will be diagnosed with a contact allergy to their implant based on signs and symptoms, she said.
Pearls for Practice
'We can approach the care for preimplant patients with the understanding that many will have nickel contact allergy,' Atwater told Medscape Medical News . 'And be prepared for conversations related to the presence of nickel in implanted materials, the likelihood of nickel release from these materials, and an understanding that some nickel-containing materials may be higher risk for cutaneous or systemic symptoms than others,' Clinicians can be better prepared for conversations with patients about whether patch testing may result in a diagnosis of implant-related contact allergy, she said.
The main study limitation was the lack of data on patient outcomes, Atwater noted. 'It would be ideal if we had data on how surgeons managed the results for our preimplant patients, such as whether they chose a different implant,' she added. For postimplant patients, more data are needed on how implants with associated contact allergy are managed, and on the long-term quality of life for patients with implant-related contact allergy, she said.
Conducting the current study at this time was extremely important because of the frequent use of medical implants, said Jennifer Chen, MD, clinical professor of dermatology at Stanford University, Stanford, California, in an interview.
Medical implants are currently extremely common, and implant complications are not rare, so it is important to learn more about the cause and presentation of delayed hypersensitivity reactions to implants, said Chen, who was not involved in the study.
'I was surprised by the high rate of reactions to titanium, since titanium is often thought of as a 'hypoallergenic' alternative to the more commonly used nickel-/cobalt-based alloys used in implants,' Chen told Medscape Medical News . In the study, titanium oxalate was one of the main allergens identified, at about 22%. More research is needed to see whether these are true positive reactions to titanium vs irritant reactions, she added.
