Biocompatibility standards

There is a wide range of tests that may be used to determine the biological response to materials. Short-term uses require only short-term tests. Long-term uses require tests applicable to the particular device and tissue type. Since not all tests are necessary for all applications, national and international standards organizations have developed matrix documents which indicate what methods are appropriate for specific applications. These documents can be used as guidelines in preparing a submission to the U.S. Food and Drug Administration (FDA) for approval of a new material or device. Similar matrix documents have been standardized by the CSA, BSI, and ISO. Test method documents have also been developed by the National Institutes of Health (N1H), the U.S. Pharmacopeia (USP), and other national organizations such as the Health Industry Manufacturers Association (HIMA). Guidelines for dental materials have also been developed by the ADA and ISO.

Much of the standards activity is now associated with the International Standards Organization (ISO) with biological evaluation of medical devices under the consideration of TC 194 and presented in the developing documents of ISO 10993. There are various parts to this document. Part 1 is definitions and the guidance on selection of evaluation test categories that should be done. The other parts of 10993 give more discussion and detail on the selection of individual tests that should be done for a particular biological interaction or biological effect (e.g., contact with blood, systemic toxicity, genotoxicity). In general, details of test methods are not given in the ISO documents and reference is made to other documents such as ASTM and USP standards for procedures and methodology.

In the following section we review some of the steps taken to establish the biocompatibility of a new material for a specific application, in this case a long-term orthopedic implant. We use ASTM standard F748 "Practice for selecting generic biological test methods for materials and devices" as a guideline. The standard test methods described are those used within ASTM.

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