A new and evolving paradigm for biocompatibility

We propose that the mechanical property of the interface between an implant and its surrounding tissues is critical for the host response and the performance of the device. The interfacial mechanics depends on several different factors related to the physical shape of the device and its surface as well as properties of the host tissue and the loading conditions of the device and surrounding tissue. It seems plausible that the growth of the fibrotic tissue to support mechanical loads is governed by the same principles as depicted by Wolfs' Law for bone. Of course, biocompatibility will have different implications depending on which vantage point we look at the host-material interface. Another implication is that only limited aspects of biocompatibility is measurable with current in vitro tests and that the elicited host response in vivo models remains crucial for evaluation of medical devices and tissue engineering constructs.