08.13.12
Graduate student Roy Junius Rusly explained in a blog post that UKA “is a surgical procedure used to treat osteoarthritis when the damage is only limited to one compartment of the knee. The main advantages of this procedure over the total knee replacement include preservation of bone stock, more physiologic joint movement, improved proprioception, increased range of motion, and faster recovery time.”
DesJardins and his team have embarked on this research project understanding that UKAs have not gained universal recognition as the appropriate procedure of arthritis of a single condyle (the rounded end of a bone where it connects to another at a joint). Rusly explains this may be due to it being a more complex procedure than total knee replacements.
With a team comprised of Ph.D. students such as Rusly, master’s students, clinical contacts, and even some undergraduates, DesJardins has been working on gathering data on existing UKAs with sights on eventually developing and marketing their own.
“The project itself is not particular to a specific UKA,” DesJardins explained to Orthopedic Design & Technology. “We will be using an industry UKA that’s currently being used in patients. We’re working to get that donated from an interested company.”
Until Clemson is able to work through the processes of getting materials on loan for research, DesJardins is focusing on “developing the technology to be able to do this testing—the rig itself and the testing apparatus—and investigating how these UKA devices affect the loading and the motion within the joint.”
The “rig” is the Clemson knee simulator:
“It is a system that we are making here in the lab that will enable us to basically take a lower leg from a cadaver and make it bend up and down, like you would if you were squatting down and getting back up off the ground,” DesJardins said. “It’s a device used in experimental labs like ours to allow us to investigate how different procedures affect the motion and loading of the knee.”
The knee simulator uses three-dimensional position tracking of the knee movement during simulation.
According to Rusly, the cadaveric specimens will be procured with help from the Greenville Hospital System. “The rig,” wrote Rusly, “has the advantages of being a reasonable simulation of the entire lower extremity in activities such as rising from a seated or crouching position while allowing measurements of internal loadings (contact pressures), which could not be performed accurately in a living patient.”
Why not measure in living patients? Well, as DesJardins explained, no one would want such an invasive procedure done purely for early stage experimental study:
“In order to get those actual pressure measurements, you have to stick something inside the knee joint, so nobody would want to have that. There are a few studies in which they get permission during surgery—during a total knee joint procedure—to put an instrument in there to measure these loads, but that’s why it’s a very invasive procedure. So what we would be doing for our experiment to work is we would be making a small incision and sticking a small instrument—a small pressure mapping film—in between the knee joint, taking those measurements, and doing the procedure and seeing how they change.”
Rusly called these pressure-mapping films “paper-thin film pressure sensors.”
There is an exception, though. There are wireless knee implants out there that can be inserted in vivo into a knee, and are capable of telemetrically transmitting data back to physicians or researchers. Of course, as is the case with all wireless devices, there is a security risk involved. DesJardins noted, however, that they are state of the art, they “certainly still fall under experimental work.” He went on to say that because such joint implants—wireless or otherwise—are expected to last for tens of years, they are in high demand and require quite an investment from a research standpoint.
The Clemson bioengineering department is on its way to bringing a potential UKA surgical implant device to the market. Though they are at the beginning of this journey, the department has filed a preliminary provisional patent on a different kind of knee implant system—which of course cannot be disclosed yet—intended to treat patients that already have gone through two or three implants that haven’t worked. This implant would fall under “reconstruction arthroplasty,” for cases where there is very little of the bone and joint left and the patient is at risk of having her knee amputated. UKAs are on the other end of the spectrum, as they are performed at the very beginning of an arthritic knee going bad. DesJardins is obviously enthusiastic about the subject and looks forward to seeing the data gathered lead to new and useful surgical technology.
“That’s what we do,” DesJardins said. “We work on measuring how these implants affect patients, and then designing new implants to make life better.”
Research to improve knee implant design, surgical techniques, and patient selection criteria is taking place at the Frank H. Stelling and C. Dayton Riddle Orthopaedic Education and Research Laboratory located on the Clemson University Biomedical Engineering Innovation Campus.
Roy Junius Rusly’s blog post can be viewed here.