Metal Implants and Immune Response: Pre- and Post-Market Methods for Evaluating Corrosion and Wear Debris from Medical Devices Containing Metal

2021 FDA Science Forum

• Authors: Arindam, Paul, FDA/CDRH; Smith, Diane, FDA/CDRH, Henry M. Jackson Foundation; Nguyen, Alexander, FDA/CDRH; Liang, Jing, FDA/CDRH; Gottipati, Anuhya, FDA/CDRH; Seo, Youngee, FDA/CDER; Park, Jin, FDA/CDER; Saylor, David, FDA/CDRH; Sussman, Eric, FDA/CDRH; Lathrop Blitzer, Sherrill, FDA/CDRH

• Center: Center for Devices and Radiological Health

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Abstract

Recent post-market signals for implants containing metals suggest that subsets of patients develop unexpected or heightened biological responses from metal exposure. Currently, recognized standards for the implantation, recovery, and assessment of implanted medical devices and associated specimens exist. Unfortunately, there is variation and disagreement regarding best practices for sample collection, processing, and analysis. Therefore, a better understanding of standardized methods for predicting the release of metal debris and evaluating release in vivo and ex vivo is critical for consistency in the evaluation of metal-containing implanted devices. The goal of this project is to work with internal and external partners to identify gaps in current standards for assessment of corrosion, wear debris, associated biological responses in patients (e.g., sampling, histology, physical and chemical analyses), as well as to assess the consistency with which the methods are applied. A survey and critical literature review assessing the availability and usefulness of methods for evaluating tribocorrosion, selecting appropriate models, conducting and evaluating in vivo imaging, measuring metal levels in body fluids and tissues, performing tissue retrieval and histological assessments, and analyzing retrieved implants were conducted. The assessment of the standard methods includes an evaluation of their utility and frequency of use. In addition, areas where reliable standard test methods are not available, were identified. Though many standards currently exist to address different goals for individual device types and materials, this endeavor provides a comprehensive perspective across medical specialties and devices for assisting stakeholders (pre- and post-market) in planning for and addressing the concerns related to metal-induced biological responses. This work will generate a comprehensive road map/resource for the standardized in vivo and ex vivo evaluation of metal implanted devices and identification of best practices for pre- and post-market studies.

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