Tag Archives: MPI

Monitoring hip and knee replacements from inside

I have a fondness for the ‘My mother is a cyborg‘ posting that I wrote for April 20, 2012 largely due to the title which amuses and makes the piece easy to find. In common with this posting, ‘My mother …’ is about  replacements (hip, etc.) and nanotechnology.

Before spilling the latest news, here’s the reason for all the research interest in hip replacements, from my April 20, 2012 posting,

Since her [my mother’s] operation, I’ve become somewhat interested in hip replacements. From the April 19, 2012 news item by Anne Trafton on Nanowerk about research at MIT (Massachusetts Institute of Technology),

Every year, more than a million Americans receive an artificial hip or knee prosthesis. Such implants are designed to last many years, but in about 17 percent of patients who receive a total joint replacement, the implant eventually loosens and has to be replaced early, which can cause dangerous complications for elderly patients.

To help minimize these burdensome operations, a team of MIT chemical engineers has developed a new coating for implants that could help them better adhere to the patient’s bone, preventing premature failure.

There’s a researcher at Case Western Reserve University (Ohio) who is taking a different approach (from the MIT team) by utilizing an emergent process, magnetic particle imaging, according to the Feb. 5, 2013 news item on Nanowerk,

A Case Western Reserve University chemistry professor has begun imbedding magnetic nanoparticles in the toughest of plastics to understand why more than 40,000 Americans must replace their knee and hip replacements annually.

Anna C. Samia, an assistant professor who specializes in metallic nanostructures, has been awarded a five-year $600,000 National Science Foundation-CAREER grant to create new materials and equipment to test ultra-high molecular weight polyethylene used to make artificial joints. She and her team of researchers will also develop magnetic particle imaging techniques to monitor degradation and wear.

The US National Science Foundation gives more information about Samia’s project on her ‘Magnetic Imaging Guided Composite Materials Development’ Career Award webpage including this non-technical summary I’ve excerpted,

Polyethylene is widely used as a component in the fabrication of joint prostheses. A major downside of this material is that it can undergo excessive wear leading to premature loosening of the implant, which in turn can lead to failure and complicated replacement revision surgeries. Studies have shown that polyethylene wear in artificial joint replacements are not always identical and are not easily explained by exclusively mechanical factors. In cases of premature and excessive wear of polyethylene bearings, chemical degradation and oxidation of the polymer can significantly lower its mechanical resistance and result in an accelerated wear-off process. While ex vivo studies have been conducted on previously used polyethylene acetabular cups to understand the factors contributing to implant failure, the degradation mechanism is still not completely understood. An improved assessment of the structural integrity of the polyethylene material used in implants as subjected to mechanical and chemical stress will provide valuable information on the material’s durability, and can help predict its wear and degradation over time. To study the real-time degradation of implant materials in various chemical and biological fluid environments, the proposed project aims to develop new polyethylene composite materials that can be investigated using an emerging imaging modality called magnetic particle imaging (MPI). The proposed research will transform the wear debris monitoring of polyethylene implant materials and impact annually one million people in the U.S. alone who undergo hip and knee replacement surgeries. The educational impact of this project will build on current initiatives to educate high school, undergraduate and graduate students through the development of cross-disciplinary courses and hands-on research programs that will incorporate the interplay between materials fabrication and imaging tools. Moreover, a modular “Traveling Magnetism Show” will be developed for K-12 students at four adaptive levels and will be showcased in local schools and science museums. In addition, a new “Women in Chemistry Workshop Series at CWRU” will be established to provide a mentoring and training platform for graduate and post-graduate female chemistry students. [emphasis mine] This program will facilitate monthly discussions and workshops to tackle important aspects of career advancement specific to women scientists.

Future applications are also being considered according to the news item on Nanowerk,

Beyond artificial knees and hips, Samia said the nanoparticles, methods and technologies developed in this study would also be useful for learning how stents, electrodes, artificial organs and other implants degrade inside the body.

“A lot of other materials are used for implants,” she said. “It will be interesting to study them over time.”

As per my emphasis earlier, it’s intriguing to note that Samia’s grant is also being applied to outreach and support programs for female chemistry students.