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Michael Monheit
Michael Monheit
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Dr. Berger’s study: Zimmer NexGen CR-Flex Porous Femoral Components – Failure Rate of 9%


For years, Dr. Richard A. Berger designed surgical tools and artificial joints for Zimmer Holdings. But those days have long passed. Dr. Berger started complaining to Zimmer that one of its artificial-knee models was failing prematurely, and he recently went public with a study that proves it.

In fact, more than 150,000 Zimmer NexGen knee implants have been sold since 2003, and the questions remain as to how many of them now require revision surgery.

One study, suggests that a certain model of Zimmer NexGen high flex knees that are not cemented, are failing at a rate as high as 9 percent after less than two years. And, that 36 percent of implants were loosening. Over half of the 100 patients that were involved in the study experienced knee pain and other problems. Patients commonly experience – device failure, knee pain, revision surgery, loosening of the implant, compensation pain and problems.

Counsel for Zimmer points out that Dr. Berger’s study relates to only 108 cases, and only to the NexGen CR-Flex Porous Femoral component, which is used in less than 4% of all NexGen cases. The NexGen brand encompasses a variety of components, the vast majority of which are not the subject of the study referenced above. For example, the many different NexGen systems and components not studied by Dr. Berger, including the NexGen CR; NexGen CRA; NexGen LPS; NexGen LPS-Flex; NexGen LPS-Flex-Fixed; NexGen LPS; NexGen Legacy LPS; ad the NexGen LCCK products.

Further, Zimmer’s counsel cites to the 2010 Australian Orthopaedic Association National Joint Replacement Registry 2010 Annual report Table KT30, pg 123 and the Swedish Knee Arthroplasty Register, Annual Report 2010, pg 30 in asserting that, Dr. Berger’s results are highly atypical and that Dr. Berger’s results stand in stark contrast to other publicly available information concerning the NexGen family of products.

In a letter to Zimmer Holdings (PDF), Senator Charles E. Grassley, addressed several concerns including, “What process does Zimmer have in place to respond to allegations and concerns raised by its consultants or contractors regarding the safety of one of its products?”

Dr. Lawrence Dorr, a Los Angeles orthopedic surgeon, shares Dr. Berger’s concerns that Zimmer’s artificial hip was failing after only a few years.

Will Components of NexGen Line Be Recalled?

The MIS tibial component is intended to promote Zimmer’s so-called “minimally invasive surgery.” A two to three inch incision is required compared to an eight to twelve inch incision. As such, many MIS components were implanted with traditional extender stems, which are used by surgeons to attach to the tibia. Zimmer claimed the MIS did not require an extender stem to anchor the artificial knee to the tibia.

The revision and failure rate of NexGen MIS was reviewed by two orthopedic surgeons in a 2010 study that compared surgeries that used extender stems versus those without. The study findings showed that MIS Tibias placed without a stem component failed 24 percent of the time compared to those with stem components which failed only 4.2 percent. In a related matter, The U.S. Food and Drug Administration (FDA) issued a Class-II recall of the NexGen MIS in September 2010, but subsequently, Zimmer clarified that the tool used during surgery was causing the problems and not the implant itself.

The agency has received complaints of loosening of the implanted device requiring revision surgery. A review of the FDA MAUDE database reveals that there may have been as many as 114 MDRs alredy filed that reported that the device loosened and the patient required additional surgery to replace the device.

At this time, long-term performance of artificial hips and knees, a $6.7 billion annual business, is not tracked. And sadly, those with the most to lose are the hundreds of thousands of people who receive an orthopedic device each year.

Product Identification Notice: In any of our web pages referring to Zimmer NexGen products, these pages are intended to provide information about and are referring to the same Zimmer products that were identified by Dr. Berger in his presentation and study entitled "The High Failure Rate of a High-Flex Total Knee Arthroplasty Design," and were written about in the NY Times article titled "Surgeon vs. Knee Maker: Who’s Rejecting Whom?," and that are reported in the FDA MAUDE database, where reports involving the Zimmer NexGen CR Flex Cementless or Porous Femoral component can be found and also those products associated with aseptic loosening of the Zimmer MIS Tibial Component that led certain doctors to discontinue its use, and to recommend discontinued use of this product in primary TKA until the etiology of the high early failure rate of this implant is determined. See prospective studies comparing the results of the Zimmer MIS Tibial Component using conventional and minimally invasive exposures as well as comparing fixation with different types of bone cement as described in Early Aseptic Loosening With a Precoated Low-Profile Tibial Component A Case Series. Not all Zimmer NexGen products are involved in our investigations and lawsuits.


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    Great article Michael. I have started to spread the word about NexGen and this article is very informative for patients to read as well as doctors and journalists. I am curious as to whether Zimmer or Dr. Berger have joined in the public discussion? It is certainly a national health issue and raises questions about why a device this got approved by the FDA in the first place. The news reports we read often seem to portray medical device requirements by the FDA as onorous and overdone. If that is so, why do so many medical devices get used on patients and then we discover serious problems as we do with DePuy, Medtronic, and many many other medical devices? Thanks for educating the public about this subject. I spoke with a friend who had two knee implants and he said that his doctor refused to volunteer the name of the device and the manufacturer. I know that he could have demanded that information but is this more of that “conspiracy of silence” that has given some doctors a bad name?

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    According to Zimmer’s counsel, following the publication of the Article in the New York Times, in July 2010, Zimmer received an inquiry from Senator Charles E. Grassley, then Ranking Member of the United States Senate Committee on Finance, regarding the Zimmer product assurance and complaint handling systems. Zimmer’s counsel states in a letter dated March 17, 2011 that, “Zimmer cooperated fully with the inquiry, emphasizing its rigorous quality programs and product complaint handling, in general, and its handling of the failures reports by one surgeon cited in The New Your Times article, in particular. Zimmer can confirm that, following meetings with Senator Grassley’s Committee staff, the Company has received notice that it has satisfactorily responded to all of the Committee’s requests pertaining to its Complaint handling system and the facts and circumstance of the specific complaints under review. The Committee staff has indicated that Senator Grassley has no further questions or requests.”