Authors: Antoine Alves, PhD; Alan Metz, PhD, DVM; and James Render, PhD, DVM
The understanding of the complex reactions involving specific implant characteristics (chemical, physical, and thermal), as well as cellular and secretory factors, collectively determines success or failure of medical devices. Understanding molecular, cellular, tissue, and organ pathobiology, in addition to the principles of healing, is essential for evaluating the local implant or tissue interface and potential systemic effects on the host. Selection of the test model, surgical technique, healing time, clinical endpoint, technique for specimen preparation, and finally morphologic (microscopic and ultrastructural) criteria are pivotal in the evaluation of the implant and host response. These criteria have to be adapted specifically for each device or biomaterial. As for the full testing program of biocompatibility, it is advised that these microscopic and ultrastructural investigations be conducted under Good Laboratory Practices or under an ISO 17025 quality system to ensure competent, reliable, and independent analysis of the implant/host response. The safety assessment of medical devices is complicated by the diversity of devices and components, but also by the variety of clinical indications for these devices. Here we discuss commonly used and innovative methods for investigating and interpreting implant and host response.