Natural Lubrication for Metal Implants

"Natural" graphite lubricant reduces wear on metal-on-metal implants

January 2, 2012 by Emily Greenhalgh

A newly discovered lubricating layer of graphite could be the key to longer-lasting metal-on-metal hip implants, according to researchers.

A study funded by the National Institutes of Health found that lubrication in metal-on-metal hip implants has more in common with the lubrication in a combustion engine than a natural joint.

The study, conducted by U.S. and German researchers, found that a lubrication layer that forms in metal-on-metal hip replacement devices is actually graphite carbon, not proteins as researchers previously suspected.

"Graphite has been used as a lubricant for over a century," study co-author Laurence Marks told Reuters. " It is a classic lubricant, and it appears to form naturally."

When they discovered the graphite lubricant, researchers from Northwestern, Rush University Medical Center and the University of Duisburg-Essen were analyzing 7 retrieved implants to find a way to stop erosion between their metal surfaces.

"This finding opens new avenues of investigation to help scientists understand how joint implants function, and to develop strategies to make them function better," Dr. Stephen Katz, director of the National Institute of Arthritis & Musculoskeletal & Skin Diseases, said in prepared remarks. "The results of such research could have important implications for several 100 thousand Americans who undergo hip replacement each year – as well as those who could benefit from the procedure, but have been advised by their doctors to delay surgery until they are older."

Hip replacements are one of the most common orthopedic surgeries in the U.S. More than 500,000 metal-on-metal implants have been performed so far, according to the FDA.

All-metal joints were designed to be more sturdy and accommodate larger femoral heads than the metal-polyethylene implants they replaced, but several studies found that patients who received the metal-on-metal implants were more likely to need repeat surgeries.

Due to the natural friction of the hip's movement, metal particles can wear off the implants and enter patients' bloodstreams, according to the federal watchdog agency.

"Problematic devices have tended to release more metal debris through wear and corrosion than devices that have performed well," lead investigator Dr. Joshua Jacobs said in prepared remarks. "This debris can cause a local tissue response involving the bone, ligaments, tendons and muscles around the hip."

Lawsuits over the implants have skyrocketed in recent months, topping 5,000 in 2011 – more than in the past 4 years combined.

The NIH researchers seemed optimistic about the lubricant discovery.

"Nowadays we can design new alloys to go in racing cars, so we should be able to do this for implants that go into human beings," Northwestern University professor Laurence Marks said in a prepared statement.

If the research doesn't pan out, growing concern could put the devices on track to be the biggest and most expensive medical implant quagmire since Medtronic (NYSE: MDT) recalled its Sprint Fidelis lead in 2007.

And the high-profile recall of Johnson & Johnson (NYSE:JNJ) subsidiary DePuy Orthopaedics' metal-on-metal ASR implant could cost $1 billion on its own.

All-metal joint replacements haven't just been a target for the federal watchdog agency. The implant woes have garnered the attention of lawmakers as well.

Three U.S. senators are calling for increased safety measures for medical devices, spurred by the attention given to the recalls. Their proposed legislation would beef up the FDA's safety regulations, allowing the federal watchdog agency to conduct safety studies of devices after they've been approved and to grant conditional approvals contingent on further trials.

SOURCE: http://www.massdevice.com/news/natural-graphite-lubricant-reduces-wear-metal-metal-implants


From Natural Health News

Natural Health News: Manufactured Parts and Hip Replacements

Aug 23, 2011 Hip Implant Complaints Surge, Even as the Dangers Are Studied. Originally posted 2009. Total Hip Arthroplasty Every year approximately 200000 hip replacement surgeries are performed in the United States and the success ...

Manufactured Parts and Hip Replacements

From Public Citizen today, 10 January, 2012

It’s never good news when a global, multibillion-dollar industry is trying to convince Washington to put its profit-making interests above public health.

The medical device industry is doing just that by lobbying the Food and Drug Administration to take shortcuts that will put millions of lives at risk.

Tell your members of Congress to oppose these dangerous shortcuts in the medical device approval process.

For example, consider the defective artificial hips manufactured by the DePuy division of multinational pharmaceutical company Johnson & Johnson. Two years ago, the company’s metal-on-metal hip implants were recalled because they carried the risk of releasing metal toxins into the hip tissue, which caused inflammation and serious internal damage.

Just a few years after receiving the hips, which were implanted in 40,000 patients in the United States (and tens of thousands more worldwide), many patients required costly, painful and risky operations to replace the devices. (1)

This is just one of many examples of medical devices that fell through the cracks of our nation’s system for regulating medical devices, injuring or killing thousands of patients.

Catastrophic failures like the all-metal hip implants show that the FDA approval process should be strengthened — not weakened.

Tell Congress: Put patient safety before corporate profits.

Shockingly, lobbyists representing the powerful medical device industry are trying to persuade lawmakers to make the already-insufficient approval process even weaker than it is.

Their aim is to ram their products through a weakened process and get their products to market as quickly as possible, even without undergoing adequate testing to assure that they are reasonably safe for patients. In other words, profits first.

We’re up against a powerful industry with tentacles of influence that reach deep into Capitol Hill. But with help from activists like you, we can fend of the attempts to weaken medical device regulation.

Please tell your members of Congress that the device approval process should be strengthened to protect the public, not abbreviated for industry profits.

October 2011
Metallic Hips Fail at a Fast Rate

August 2011

Hip Implant Complaints Surge, Even as the Dangers Are Studied

Originally posted 2009

Total Hip Arthroplasty
Every year approximately 200,000 hip replacement surgeries are performed in the United States and the success rate appears to be about 90 percent. The most common reason for hip replacement is osteoarthritis of the hip joint; however, surgery is not a “quick fix” for every person with chronic hip pain. Surgery, in this instance is used only after medication and other, less-aggressive treatments have failed.
More than 21 million people in the United States have degenerative osteoarthritis, and it is the leading cause of chronic disability. The number of arthritis related hospital admissions doubled between 1993 and 2006.
Most people undergo hip replacement as a result of osteoarthritis of the hip joint. But you might also consider hip replacement if you experience severe pain, loss of motion or deformity of your hip joint. Hip replacement is also used in people with hip injuries, rheumatoid arthritis, impaired nerves, loss of muscle strength surrounding the joint, and other medical conditions, such as a bone tumor or bone loss due to insufficient blood supply (avascular necrosis).
Symptoms that may lead to the decision to undergo hip replacement include severe pain and loss of motion or stiffness in the joint. Pain that keeps you awake at night, little or no relief from pain medications, difficulty walking up or down stairs, trouble standing from a seated position, or having to stop activities because of pain are additional considerations that can lead to interference in everyday living.
Today’s hip prosthetics can be expected to last up to 20 years. Usually hip replacement has been an option for adults older than age 60. Because the newer technology has brought about stronger and longer lasting artificial joints, younger and more active people are choosing this surgery.
Hip replacement may be the only choice after failure of other less invasive therapy fails to relive increasing pain. While hip replacement, or total hip arthroplasty, can relieve pain and improve range of motion, it is not without risk.
The current rate of obesity is of major concern to surgeons who provide this type of orthopedic surgery. Only recently has this data been made available through the Mayo Clinic.
Researchers have found that there is a 50 percent increase in complications when obesity and super obesity is present. In order to be considered a “best candidate” for hip replacement surgery, there must first be significant joint and cartilage damage shown on X-ray, severe and deep pain, no relief from medication for pain and inflammation, and interference in daily activities of living.
Usually if a patient has disabling heart disease, uncontrolled high blood pressure, infection or very poor overall health, this surgery will not be scheduled.
Currently either metal-metal or ceramic-metal hip prostheses are used in replacement surgery.
A third type of prosthetic hip joint was in use from 2003 until 2008. In July 2008, the “Zimmer Durom Acetabular Cup,” a metal-polyethylene prosthetic device, was removed from the market. At that time the manufacturer began a significant effort to provide new training to orthopedic and general surgeons and began to develop new educational support materials.
Considered by surgeons for at least 30 years to be highly durable, the Metal-on-Polyethylene prostheses had been the leading artificial hip component material and had been approved.
The Zimmer Durom hip replacement device is made with a cobalt chrome molybdenum alloy metal ball with a polyethylene liner. Polyethylene is the most understood and had been the most used of all liner materials, which offered surgeons a range of stability options while the operation was underway.
The ability of polyethylene to be adaptively customized during surgery is considered important; however it is the least expensive bearing.
Since all implants, including the Zimmer Durom hip implant device, are subject to wear and tear, they shed debris. After about 10 to 15 years of use the debris shows up with symptoms of inflammation and bone loss. The wear rate of Metal-on-Polyethylene implants, such as the Zimmer Durom hip replacement device, is about 0.1 millimeters a year.
To overcome the issue of “debris” manufacturers chose to treat the polyethylene liners with radiation to create new wear resistant polyethylene. This new substance is called “highly cross linked polyethylene.”
In July 2008, after reviewing data on more than 3,000 cases, Zimmer, the world's largest manufacturer of hip replacement parts, suspended sales of the Zimmer Durom Acetabular Component (Durom Cup).
The Indiana-based manufacturer states that it was unaware of any design or manufacturing defects and a Zimmer Durom hip recall was not issued. Zimmer has plans to place the Durom Cup back on the market on completion of its training and education projects.
Several Zimmer Durom hip implant lawsuits have been filed against Zimmer Holdings Inc., claiming it failed to provide proper warnings, instructions and training to surgeons.
In early 2008, one prominent orthopedic surgeon wrote openly about problems he experienced with Zimmer Durom hip replacements. His data showed that out of 165 implants, 14 were "revised or required revision" within the first two years after surgery. The surgeon added that he believed the Zimmer Durom hip replacement device was defective and there were seating problems with the surface where fixation in the natural joint was to occur.
Zimmer advised that people who have received the Durom Cup to contact their doctor if they experience pain more than three months after surgery.
This article is part of a consumer health education series written by Gayle Eversole, DHom, PhD, MH, NP, ND, of Creating Health Institute, in collaboration with Bernstein Liebhard, LLP.

The views expressed in this article are solely those of the author, Gayle Eversole.