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New discovery could lead to better artificial hips

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December 27, 2011

A new discovery regarding a naturally-occurring lubricating layer on artificial hip joints...

A new discovery regarding a naturally-occurring lubricating layer on artificial hip joints could lead to longer-lasting prosthetic hips

For many people who have suffered from an arthritic hip, the replacement of their natural hip bone with a prosthetic implant has meant an end to constant pain, and the restoration of a normal range of movement. Unfortunately, the ball-and-socket joints of the prostheses do wear down over time, so younger patients in need of the implants are typically told to either wait until they are older, or must face the prospect of someday requiring repeat surgery to service their device. A recent discovery, however, could lead to longer-lasting artificial hip joints - this could in turn allow patients to receive prosthetic hips at a younger age, without the need for additional surgery when they get older.

Although a previous generation of artificial hips used a combination of metal and polyethylene surfaces for their ball-and-socket joints, these have since largely been replaced with longer-lasting metal-on-metal joints. It had previously been observed that over time, a lubricating layer formed between the two metal surfaces, once the implant had been in use in the body. Scientists generally assumed that this layer was made from some sort of protein from the body, as is the case with natural skeletal joints.

Recently, however, a team of physicians and engineers from the United States and Germany analyzed the lubricating layer on metal joint components that had been removed from patients in revision surgeries. To their surprise, they discovered that the layer was composed at least partly of graphite carbon. This is a solid lubricant, which is typically used in industrial applications.

"Knowing that the structure is graphitic carbon really opens up the possibility that we may be able to manipulate the system in such a way as to produce graphitic surfaces," said team member Dr. Alfons Fischer, of Germany's University of Duisburg-Essen. "We now have a target for how we can improve the performance of these devices."

The researchers now plan on correlating the condition of layers on removed implants with those implants' reasons for removal. They are also studying how neighboring cells could be affected by graphite particles that flake off of artificial hip joints.

The study was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. A paper on the research was published on December 23rd in the journal Science.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
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3 Comments

I researched in this area many years ago (1984 - 1996) we worked to develop replacements for metal on metal and this evolved to an ultra high density polyethylene socket with a zirconia ball developed by CSIRO. This research was instigated by surgeons who were convinced that any metal joint produced toxic wear debris in the long term.

Both my father and a good friend had 2 UHDPE/ZrO hips fitted and for my father this lasted for the rest of his life (>15 years) and he took long walks daily right to the end. My friend is still going on his hip replacements (~20 years) regularly mowing lawns etc etc.

Light_Lab
27th December, 2011 @ 08:41 pm PST

I have had both my hips have been replaced, the earler one was from Wrightington Hospital the hospital that invented them! their early models where made from all surgical stainless steel! so idea is not new

Davy Jones
28th December, 2011 @ 03:21 am PST

Is the carbon of the graphite comming from proteins? crushing and pressing those molecules until only carbon remains? D:

Izlxe
28th December, 2011 @ 10:25 pm PST
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