Helping people to hear

Using advanced techniques at the Canadian Light Source (CLS) at the University of Saskatchewan, scientists have created three-dimensional images of the complex interior anatomy of the human ear, information that is key to improving the design and placement of cochlear implants.
“With the images, we can now see the relationship between the cochlear implant electrode and the soft tissue, and we can design electrodes to better fit the cochlea,” said Dr. Helge Rask-Andersen, senior professor at Uppsala University in Sweden.
“The technique is fantastic and we can now assess the human inner ear in a very detailed way.”
The cochlea is the part of the inner ear that looks like a snail shell and receives sound in the form of vibrations. In cases of hearing loss, cochlear implants are used to bypass damaged parts of the ear and directly stimulate the auditory nerve. The implant generates signals that travel via the auditory nerve to the brain and are recognized as sound.
By imaging the soft and bony structures of the inner ear with implant electrodes in place, Rask-Andersen said the researchers were able to discover what the auditory nerve looks like in three dimensions, and to learn how cochlear implant electrodes behave inside the cochlea. This is very important when cochlear implants are considered for people with limited hearing.

>Read more on the Canadian Light Source website

Image: the inner ear

Research shows how to improve the bond between implants and bone

Research carried out recently at the Canadian Light Source (CLS) in Saskatoon has revealed promising information about how to build a better dental implant, one that integrates more readily with bone to reduce the risk of failure.

“There are millions of dental and orthopedic implants placed every year in North America and a certain number of them always fail, even in healthy people with healthy bone,” said Kathryn Grandfield, assistant professor in the Department of Materials Science and Engineering at McMaster University in Hamilton.

A dental implant restores function after a tooth is lost or removed. It is usually a screw shaped implant that is placed in the jaw bone and acts as the tooth roots, while an artificial tooth is placed on top. The implant portion is the artificial root that holds an artificial tooth in place.

Grandfield led a study that showed altering the surface of a titanium implant improved its connection to the surrounding bone. It is a finding that may well be applicable to other kinds of metal implants, including engineered knees and hips, and even plates used to secure bone fractures.

About three million people in North America receive dental implants annually. While the failure rate is only one to two percent, “one or two percent of three million is a lot,” she said. Orthopedic implants fail up to five per cent of the time within the first 10 years; the expected life of these devices is about 20 to 25 years, she added.

“What we’re trying to discover is why they fail, and why the implants that are successful work. Our goal is to understand the bone-implant interface in order to improve the design of implants.”

>Read more on the Canadian Light Source website

Investigation of metal deposition in organs after joint replacement

Synchrotron analysis shows potentially harmful metals from implants can find their way into human organs.

The hip replacement is considered to be one of the most successful orthopaedic interventions, with 75,000 performed each year by the NHS alone. However, the implants used to replace hips contain metals, such as chromium and cobalt, which are potentially toxic and which can be deposited into tissues around the implant site due to wear and corrosion. A team of researchers used X-ray absorption spectroscopy (XAS) on the I18 beamline to show that these metals can also find their way into organ tissues. Their results suggest that chronic diseases, such as diabetes, may create conditions in which mildly toxic trivalent chromium (CrIII) particles from replacement joints are reoxidised within the body to form carcinogenic hexavalent chromium (CrVI). Their results have been published in the Journal of Trace Elements in Medicine and Biology.

>Read more on the Diamond Light Source website

Image: Overview of the study (entire figure to see here).