Hordes of baby boomers are being shepherded into old age. As they enter their twilight years, a lifetime of pressure will begin to take its toll on these aging hips and knees. Long life spans and active lifestyles mean that this generation needs durable implants. And many people expect advancements in biomaterials to be the key. After all, an implant is only as good as the biomaterial from which it is made. Materials such as ceramics, nitinol, titanium, and synthetic polymers are prized for being inert and nonleachable.
But are they really the best solution for implant improvement?
Buddy Ratner, director of the National Science Foundation research center University of Washington Engineered Biomaterials, doesn’t think so. Ratner penned a perspective, recently published in International Polymer online, that questions the efficacy of these conventional implantable materials. Ratner asks, if the body’s response to the implant is to isolate it, is the material truly biocompatible?
He points out that the body’s natural reaction to an implant is to form a collagenous avascular sac that walls off the device from the body. The device is deemed biocompatible if the sac is thin and the foreign body reaction (FBR) site is dormant 1 month after implantation. Ratner suggests that reduced implant life span and effectiveness, as well as some infections, could be ascribed to this FBR.
"The obvious problem with our present materials is that they are inert: there are few, if any, things in normal biology that are inert," he writes. "Biology is specific, reactive, degradative, kinetic, and dynamic, and we too must embrace these principles."
Scientists should instead strive to form materials that react positively with the body, Ratner states. He urges his peers to probe the possibility of making materials that actually stimulate healing and reconstruction when implanted.
This goal is far from simple, and Ratner admits that. In his essay, Ratner enumerates points that scientists should consider in the quest for these genuinely biocompatible materials. Among them are inhibiting nonspecific protein adsorption on biomaterials, modifying existing substrate polymer surfaces, and engineering porosities.
Ratner presents a compelling argument.
The creation of materials that interact with the body in a natural way is an avenue certainly worth exploring. Engaging the body instead of working against it—or even independent of it— makes sense.
We are often so set in our ways that it is difficult to step back and ask if the accepted method or definition is the best one. Acting as a catalyst for change or simply questioning the norm is important in the medical device industry. It is often worth listening to these lone voices, especially if what they’re saying may enhance patient health.
Shana Leonard, Managing Editor