MIT engineers are using nanotechnology to develop coatings for implants that will make hip and knee replacements more durable.
Kern: More than a million Americans receive an artificial hip or knee replacement each year, and while these devices are intended to last several decades, nearly 17% have to be redone early. Dr. Lyndon Joseph, a program officer at NIH's National Institute of Aging says these “revision” surgeries are often more difficult for patients than the original replacements.
Joseph: To do it a second time is even more traumatic because they have to take out the implant, give you a big dose of antibiotics and painkillers and so you're basically laid up in a hospital for an extended period of time up to weeks to months.
Kern: NIH grantees within the chemical engineering department at the Massachusetts Institute of Technology have come up with a new way to make hip and knee replacements more durable. Currently, surgeons use a fixative called bone cement to adhere a patient's existing bone into the socket of an artificial hip or knee. But, this cement bond can give way over time. MIT engineers have recently developed a coating for the implanted device that will help with adhesion.
The coating consists of a very thin layer of proteins called growth factors. These special factors can cause stem cells --found in a patient's bone marrow-- to turn into bone-producing cells or osteoblasts. The goal is for these newly generated osteoblasts to then fill in the spaces around the implant with bone, thereby eliminating the need for cement.
Joseph: With this technology here, using these growth factors, the implantation then actually fuses better with the bone and so you have a stronger connection with implants and the bone and the structure around it so it's more stable and it lasts a little bit longer.
Kern: Previous attempts have been made to release growth factors onto implants without much success. In one case, the coating was too thick, causing it to break away from the bone. In other, surgeons directly injected growth factors onto the implant, but most drained away from the site. MIT engineers hope to get around these issues by using special nanotechnology to design a coating that is slightly less than a micron or one-thousandth of a millimeter. The thin coating has a better chance of staying on the joint and allows for a more controlled release of the growth factors. So far, the coating has achieved promising results in several animal studies. Still, Dr. Joseph says the technology is years away from making it to the operating room.
Joseph: It's still in the discovery phase. I's still in the animal phase. The big thing is when they then translate it into the human phase tha's going to be the big bang for the buck. When this is going to happen, it's anybody's guess, but I know that there's a lot of work going on out there not only NIH sponsored but industry sponsored work.
Kern: Dr. Joseph speculates on how this new technology could impact patients in the future.
Joseph: In the long run, I think it'll be easier for people to decide whether or not to go ahead with this, the surgery because as you pointed out, it is a major surgery and you're laid up for quite some time. I think it will improve the whole process a lot quicker than it is right now and that's the whole point of science is to always keep pushing the envelope and making things a lot easier and a lot better for the public.
Kern: For more information about new joint replacement technology, visit www.nia.nih.gov. For NIH Radio, this is Margot Kern— NIH...Turning Discovery Into Health®