August 10, 2004 – When patients undergo hip replacement surgery, they can hope for 10 to 15 years of use before the implant wears out. After that, they will need another artificial hip--a surgery that will probably be less successful than the first one. And for a handful of unlucky patients, a hip replacement will fail within the first year, requiring another surgery.
A research team led by University of Alberta chemistry professor Dr. Hisham Fenniri is working to change that outcome. Using nanotechnology, the team is developing a method for making artificial hips last longer. If the technique works, it could make hip replacement surgery more economical and minimize patient pain.
"The goal of our work is to minimize the number of surgeries a person goes through in a lifetime,” said Fenniri. "You want an implant that will last the longest possible amount of time."
With life expectancy increasing, the number of people requiring more than one artificial hip in their lifetime is also rising, so there is a growing need for more effective surgery, he said. Between 1990 and 2000, the number of hip replacements in the United States increased 33 per cent to 152,000 surgeries.
"The population is getting older in general and people are doing more demanding physical activities for recreational purposes," added Dr. Nadr Jomha, an orthopedic surgeon and U of A professor collaborating with Fenniri on the research.
By synthesizing tiny bumps on the surface of an artificial hip, bone cells may better adhere to the implant, more solidly anchoring it to other bones of the body. The bumps, made of synthesized organic molecules, are 3.5 to 4 nanometres in size. A nanometre is one billionth of a metre, and each nanometre is three to five atoms wide.
"If these bumps can integrate (the implant) into the bone better, then there is a possibility that the implants will not fail as often or as quickly," Jomha said.
The bumps are tubular structures self-assembled by organic molecules synthesized in a lab. Currently, Fenniri's team is determining which kinds of materials will make the best bumps, but regardless of what materials are used, the bumps will be composed of organic matter. These bumps are designed to break down and be absorbed into the body after bone cells have adhered to the implant.
Fenniri’s work began in 1997, when he started developing methods to make tubular structures on a nanoscale. In 2001, he began to explore how these structures could be used for bone implants.
He explains that this research has been a rather slow process, but adds, "It's not a cookbook procedure." In the new and quickly growing field of nanotechnology, how one moves from one experimental stage to another can be unpredictable.
Thus far, cell experimentation has yielded good results, and Fenniri's team will soon move onto animal studies before clinical trials are considered.
"So far it's extremely promising," he said, adding that his team is proceeding with caution, and is examining the potential risks of the new technology.
"Like any new technology, especially technology affecting our daily lives, we have to be very careful," Fenniri said.
In the case of nanoparticles, Fenniri explained that there has been much discussion regarding the risks of introducing the tiny structures into the body. Some researchers have hypothesized that nanoparticles may damage cells or pass through the brain blood barrier.
From his own research, Fenniri believes that since the DNA-based nanostructures are organic and will break down in the body after a period of time, the risks are minimal.
"This is what we forecast; what happens in reality, we'll have to investigate."
Fenniri is conducting his research through the National Research Council's National Insitute for Nanotechnology (NINT) based at the U of A. His collaborators on this project, and other nanotechnology projects, come from a wide variety of scientific disciplines. Researchers at NINT include experts in organic and inorganic chemistry, physicists and medical researchers.
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