Good discussion!
Sorry for coming late to the party, but I think I can make the two ends meet...
The best / most qualified way to run the biological risk evaluation process as per 10993 (in non-trivial cases) is with the support of a qualified and experienced toxicologist. The accredited test houses always have them on board, so although not cheap I would recommend engaging with such a test house for that purpose. That doesn't necessarily mean any testing will have to be done. If indeed the analysis output will be no-testing, this route will cost just a fraction of the typical biocomp testing engagement.
I believe that the "knowledgeable individual" that the guidance referred to was that toxicologist...
The analysis may include examination of master files (if available - not so easy to get formulation info from suppliers) and other documentation, and/or "equivalence testing" which is aimed at showing that the materials from the 2 different sources are equivalent from a biological reaction perspective. Such testing is usually simpler, cheaper and quicker than the full-blast biocomp test set (if required).
To wrap up: I agree that the starting point is re-evaluating according to 10993 & FDA guidance. I also agree that it may well end up in a paper risk evaluation. The important bit is to get a qualified and experienced toxicologist involved in that evaluation, so as to give it validity and hopefully reduce actual re-testing to the minimum.
Side note: USP class VI (and that entire classification, for that matter) is outdated in the context of biological evaluation for medical devices. It was phased out when the FDA endorsed ISO 10993, years and years ago. I'm not sure why it stayed around for so long, but it seems to occasionally show up when medical devices design is being discussed.
Thank you both for your help in the matter! It is interesting that USP classification is completely outdated while still being used regularly, however I do think it is a good indication for manufacturers that they will likely pass their biocomp testing. I can't imagine much worse than choosing a material you assumed would be biocompatibility then failing implantation studies, which I guess keeping USP classification on material information may help avoid. Thanks again for the help!