Interesting research is being pursued by a team out of the Weldon School of Biomedical Engineering at Purdue University. Using hydraulic machines and software, the research aims to improve physiologic performance and duration of spinal implants:
Implants are attached to spines from cadavers, and then the spines are tested in the Purdue Spine Simulator, a hydraulic machine that recreates the spine’s natural movements and shows how the implants stand up to everyday activities.
Data from the experiments also are being used to validate a complex computer model, which companies will use to test implants. The software is a “finite element model,” an application widely used in industry that contains a series of geometric shapes, such as rectangles and triangles, each providing specific data describing a part’s strength and other characteristics.
“Creating implants for the spine presents interesting challenges, different from those encountered in implants for other parts of the body, such as the hips and knees,” said Eric Nauman, an assistant professor of mechanical engineering.
Some implants made of titanium and other materials are used to treat conditions such as arthritis, in cases when a portion of the spine has been removed. Bracket-like implants called “pedicle bridges” help to keep the spine stable after the diseased portion has been removed. Other implants include artificial disks to replace disks that are damaged from wear or disease in the lower back and cervical region.
One of the machines designed by the Purdue engineers is used specifically to test implants for the cervical spine.
“There is much more movement in the cervical spine than in the lumbar portion, so what we are primarily testing with this machine is how well implants will stand up to wear over a period of about 10 years,” said Shreekant Gayakar, a graduate student in mechanical engineering. “We are replicating the range of motions seen in the human neck.”
The machine tests ball-and-socket-like implants such as the ones inserted during surgeries to replace damaged parts in the cervical spine.
“In order for implants to be approved by the Food and Drug Administration, it has to be shown that they can last 10 million cycles, or 10 million movements, which translates into about 10 years of living,” Hillberry said. “Our goal is to complete 10 million cycles over a four-month period.”
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