Research

April 2008

Using potent anticoagulants such as low-molecular-weight heparin to prevent pulmonary embolism in total hip or knee arthroplasty patients, as recommended by the Chest Physicians Consensus Statement, may actually increase the risk of all-cause mortality compared to multimodal prophylaxis measures, according to a systematic literature review published in Clinical Orthopaedics and Related Research.

"We believe the American College of Chest Physicians should reconsider their guidelines to reflect the fact that PE (pulmonary embolism) occurs despite the use of potent anticoagulants and may, in fact, expose patients to increased mortality after surgery," the authors said in the study.

Nigel E. Sharrock, BMedSci, MB, ChB, and colleagues at the Hospital for Special Surgery, New York, conducted the systematic review, which included 20 English language studies published during the last 9 years. The researchers focused on studies that involved patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) and divided publications into three categories based on the venous thromboembolism prophylaxis regimen.

Specifically, Group A included the use of low-molecular-weight heparin, ximelagatran, fondaparinux or rivaroxaban, Group B included the use of a multimodal prophylaxis, and Group C included the use of warfarin.

"Multimodal prophylaxis (Group B) was defined as a protocol consisting of intention to use regional anesthesia (epidural or spinal) with or without intraoperative heparin during surgery or pneumatic compression and aspirin after surgery," the study authors noted.

The researchers found that the lowest number of deaths occurred among patients in Group B. Patients in Groups A and C were more than two times as likely to die compared to those in Group B, with no significant difference between Group A and Group C.

Patients in Group A also had a 60% to 70% higher risk of nonfatal PE compared to patients in Group B.

Nonfatal PE occurred in 94 of 15,839 patients in Group A (0.6%) vs. 25 of 7,193 patients in Group B (0.35%), according to the study.

"We show clinical PE occurs despite the use of powerful anticoagulants. The rate of 0.6% is comparable to the rate of 1% previously described with warfarin and low-molecular-weight heparin in cohort studies.

"This literature cannot support the use of powerful anticoagulants to prevent PE, although they clearly reduce the risk of venographically evident deep vein thrombosis," the study authors wrote.

For more information:

Sharrock NE, Gonzalez Della Valle A, Go G, et al. Potent anticoagulants are associated with a higher all-cause mortality rate after hip and knee arthroplasty. Clin Orthop Relat Res. 2008;466:714-721.

What is the BMHR and Why do we need it?

View Youtube Video about BMHR by Mr. McMinn by click below:

BMHR Video Part 1

BMHR Video Part 2

BMHR Video Part 3

Derek McMinn talks about the Birmingham Mid Head Resection prosthesis and its applied use in patients with Avascular Necrosis.

For patients with osteonecrosis involving a larger volume of the femoral head, an uncemented short-stemmed prosthesis, the Birmingham Mid Head Resection, BMHR, (MMT Ltd, Birmingham, United Kingdom, now Smith and Nephew Orthopaedics Ltd, Bromsgrove, United Kingdom) was developed.

Mr. McMinn has implanted about 40 BMHRs to date March 2008.

Illustration showing the three types of prostheses implanted in patients with femoral head avascular necrosis

A new surgical robot is making medical undergraduates three times more accurate during practice hip operations, according to pilot study to be discussed at a conference this week (8 February 2008).

Link News Website

 

Delegates at the British Society for Computer Aided Orthopaedic Surgery Conference will hear that results from a pilot study saw graduates 95 per cent more confident using this robotic technique than when using conventional surgical methods in training.

 

Professor Justin Cobb, Head of the Biosurgery and Surgical Technology Group at Imperial College London, conducted the trial on 32 undergraduate medical students at Imperial College London from December 2006 to December 2007. The pilot study tested whether planning before an operation, combined with the latest robotic navigation equipment could increase the success rates of students practising hip resurfacing arthroplasty procedures – a method for correcting painful hip bone deformities by coating the femoral head with a cast of chrome alloy.

Link  http://www.memphisdailynews.com/Editorial/StoryLead.aspx?id=100097

Though the Birmingham hip is considered the industry standard, founders of another Memphis company, Active Implants Corp., said they believe they can play leapfrog with hip resurfacing using an advanced polymer first developed for Israeli Navy boat hulls.

"We're now approved in all of Europe," said Stephen Bradshaw, president and CEO of Active Implants. "We start hip surgery this week in Germany, Italy, Greece and Israel. My technology will not be available in the U.S. for quite a while, and we already have patients planning to go to Europe to get it done."

He's careful not to criticize the FDA's gate keeping, but said that new medical technology will continue to emerge first in Europe.

"I'm going to where the market opportunity is," he said. "They do almost 200,000 hip replacements a year in Germany, so it's high volume and a more friendly regulatory environment. That's why you have medical tourism; it's not the cost, but countries outside the U.S. are getting new technology faster."

Know thy information

Younger, better informed patients are not afraid of flying to Europe or even India for surgery, Bradshaw said.
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That compels manufacturers to present accurate information on their Web sites, Waugh said, and usually to assist people in finding a doctor who is familiar with the procedure.

"Surgeons have turned this into a marketing opportunity," he said. "A person wants to go to a surgeon with experience."

The AOA hip report bodes well for all manufacturers in the arena, Bradshaw said, alleviating early concerns that resurfacing may not be viable because the components are so small compared to traditional implants. With that concern gone, he said, it's now time for companies to duke it out based on clinical performance.

The AOA exhaustively collects implant data from surgeons across Australia, publishing unbiased statistics on such things as the number of procedures, component years, and revision rates, which are repeat surgeries to replace or repair an implant.

In Australia the Birmingham hip has been implanted 6,773 times, logging 19,585 component years, a cumulative measure of years in use - a common measure when assessing durability. Of those, 166 hips saw revision, a rate of 2.5 percent, by far the lowest rate. Other brands had revision rates of 4.4 percent to 8.4 percent.

"The AOA gets excellent participation; it's one of the most compliant registries in the world," Waugh said. "Whether you're an orthopedic manufacturer or a surgeon, this is a great way to see how something performs in the real world."

Counting sheep

Expect to see Smith & Nephew use the findings in educational materials for both surgeons and consumers. The Internet has permanently altered the way people manage their health care, Waugh said, with patients armed with information to discuss with their doctors.

That's already evidenced by aging athletes who have become celebrity spokespeople for implants. Tennis star Jimmy Connor plugs the Conserve total hip, manufactured by Wright Medical Technology Inc. of Arlington. At 38, former Olympic gymnast Mary Lou Retton got a new hip from Biomet Inc. of Warsaw, Ind. Golfer Jack Nicklaus was so pleased with his hip from Stryker Corp. that he's now its spokesman.

One budding issue in orthopedics is metal ionization, the microscopic fragments of metal that rub off a device and enter the blood stream. Some early studies suggest that metal-on-metal has a higher ionization rate compared to metal-on-plastic, but there is no evidence that this has any detrimental effects. What is proven is that metal-on-plastic releases polyethylene, linked to a condition that causes bone to shrink and eventual implant failure.

A 1999 study at the Avon Orthopaedic Centre in Bristol, England, compared both types and found the metal-on-metal ionization not to be significant.

Bradshaw said he can avoid that entire concern with his polycarbonate products. In one test, researchers at Leeds University in England subjected the material to 5 million cycles - equal to about 10 years worth of walking - and found no wear.

As an aside, Active Implants is also developing an artificial meniscus, or fibrous cartilage within a joint, from the same material to treat torn cartilage in the knee. The meniscus is now undergoing field trials. Because sheep knees are similar to human knees, dozens of the animals are scampering around a pasture in Israel with a polycarbonate meniscus.<

Link http://findarticles.com/p/articles/mi_m0EIN/is_2006_Sept_18/ai_n16729494/


MEMPHIS, Tenn. -- Active Implants Corporation (AIC), a pioneer in pliable orthopaedic implant technology, today announced CE Mark approval for its novel low wear, polymer hip implant which allows the sale of the product throughout Europe.

The AIC Hip Buffer(TM) is a press-fit, low wear polycarbonate polyurethane acetabular cup. This acetabular implant allows for larger femoral head sizes that should enhance joint stability and improve range of motion and shock absorption. The AIC Hip Buffer(TM) has potential applications in both total hip (complete replacement of the joint) and hip resurfacing (replacement of just the surface) surgical procedures, providing a less invasive implant with low wear metal-polymer characteristics. The company will implement a post-approval controlled release of the Hip Buffer(TM).

The AIC Hip Buffer(TM) introduces advanced low wear, pliable materials and innovative implant designs that are less invasive, bone sparing and expected to restore closer to normal joint function. The materials used by AIC are at least 50 times more pliable than all other materials used for this application and can allow for a better and more normal stress transfer to surrounding bone.

"We view this as disruptive technology and are pleased with our progress working closely with leading orthopaedic surgeons on establishing the clinical safety and efficacy of our novel implant technology" said Stephen Bradshaw, President and Chief Executive Officer of AIC. "Following more than a decade of research and development work, the Hip Buffer(TM) marks the beginning of a new generation of resilient implant solutions with a potential broad range of applications in the extremity joints and spine."

About Active Implants Corporation

Active Implants Corporation is a privately-held company formed in 2004 by an experienced team of orthopaedic executives and inventor with vast experience in advanced, pliable materials. AIC owns a robust intellectual property estate of innovative implant solutions and minimally invasive surgery technology with a potential broad range of medical applications. Headquartered in Memphis, Tennessee, the mission of the company is to serve the emerging "Interventional Arthroplasty" market by providing earlier in life orthopaedic implant solutions.