Biomaterials: Better Solution for Knee RepairProfessor Michelle Blum and doctoral candidate Allen Osaheni G’15, G’17 work with a biotri-bometer to test the hydrogel they are developing.
Oh, those aching, creaking knees. In a Syracuse Biomaterials Institute (SBI) laboratory, mechanical engineering doctoral candidate Allen Osaheni G’15, G’17 is testing a new biomaterial that could one day mend damaged articular cartilage, allowing people hampered by such knee problems to return to action, full throttle. The material—a self-sustaining, lubricating hydrogel—would act as an implant, patching torn cartilage (which heals slowly, if at all) and offering an alternative to knee replacement or other methods of repair. “Right now, knee replacement is the only comprehensive solution and it’s really undesirable for younger people who want to go back to full activity levels,” Osaheni says.
For the past three years, Osaheni has been developing the hydrogel—a scaffold of polymers that retains water—as part of a research group led by Professor Michelle Blum of the Department of Mechanical and Aerospace Engineering in the College of Engineering and Computer Science. According to Blum, whose research focuses on repairing knee joints, the major challenge is for the hydrogel to possess mechanical stability as well as friction and wear properties that mimic natural cartilage. “Our system mechanically matches cartilage and now we’re focusing on enhancing the wear life while not damaging the healthy cartilage,” she says. “The goal is for these gels to have an extended wear life beyond what typical implants have. This is specifically addressing using a synthetic implant that will allow people to maintain as much of their natural tissue as possible, therefore maintaining natural joint mechanics, so in theory people can return to a full quality of life.”
In pursuing the desired hydrogel, they collaborated with former SBI director Patrick Mather, a polymers expert, who introduced zwitterionic polymers as a lubricant in their system. They came up with two approaches for consistently producing this hydrogel blend, for which they’ve filed a patent application. One method mixes the lubricant into the hydrogel matrix; the second grafts the lubricant to the surface of the matrix. Osaheni is now exploring a process that combines the two methods. “Basically, you have this polymer floating in the matrix of another polymer that’s bigger,” Blum says. “If you push on it, or even by natural diffusive processes, it will come out of the gel, lubricating it. If the polymer is grafted on top and a piece gets knocked off, you have this reservoir that will take its place. It should enhance the lubrication properties of the gel far beyond what you need.”
This semester, they are testing the hydrogel in a device known as a biotribometer, which imitates the range of motion found in a knee, allowing them to test the biomaterial’s response to friction and wear. The biotribometer was built by two former members of Blum’s research team—then engineering graduate student Ryan Olson ’14, G’16, who developed the device; and mechanical engineering major Gabriel Smolnycki ’17, who provided electrical engineering and computer programming assistance. Most important, the device was designed to fit into an environmental chamber, where they can simulate conditions in a knee joint (such as temperature, relative humidity, and atmospheric pressure), test the material’s interaction with natural cartilage, and also introduce living cells into the matrix. “The ultimate goal is to have this implant to stabilize the wound, so recovery would be quicker and you could get back to normal life,” Blum says. “Over the long term, if you seed it with growth factors and stem cells, new tissue would form and eventually your tissue would grow back with the implant underneath it, but it would operate like natural tissue again.” —Jay Cox