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Brett Emison
Brett Emison
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Zimmer Knee Problems: Studies Evaluate Post-Op Merits Of Zimmer Knee Products

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Studies question post-op merits of Zimmer artificial knee products like NexGen LPS-FlexI’ve written previously about reported Zimmer knee problems. There has already been a recall of the Zimmer NexGen stemmed tibial component and orthopedic surgeons have called for a recall of the Zimmer NexGen CR-Flex artificial knee. The New York Times and other media outlets have covered this story, so the topic is no secret — even Sen. Chuck Grassley has written a letter calling out Zimmer — but there are other more in-depth reports publicly available that explore issues revolving around Zimmer artificial knees. To varying degrees, these reports raise significant questions about the post-operative qualities of life for the patients involved.

In a European Federation of National Associations of Orthopaedics and Traumatology report titled “Are High Flexion Activities after High-Flex Total Knee Replacement Safe?”, researcher examined the factors contributing to what the researchers determined was a “high rate of aseptic loosening in femoral components of LPS-flex TKAs”. The study relied on data obtained from March 2003 to September 2004.

The report’s main conclusion offers mixed results for the Zimmer NexGen LPS-Flex knee replacement:The high-flex implant allowed for greater range of motion and high-flexion activities, and however, showed high rate of early femoral component loosening, which was associated with weight-bearing high-flexion activities.” This report was authored by S. Kang; K. Sup Yoon; and H. Soo Han, and was published in the Journal of Bone and Joint Surgery – British Volume, Vol 92-B, Issue SUPP_II, 322.

Also published by the Journal of Bone and Joint Surgery, another significant study found that “no clinically relevant or statistically significant improvement was obtained in flexion with the ‘high-flex’ prostheses.” This “meta-analysis” was conducted by R. Mehin, MD, MHSc, FRCSC, Orthopaedic Surgeon; R. S. Burnett, MD, FRCS(C), Dipl ABOS, Orthopaedic Surgeon; and P. M. A. Brasher, PhD, Senior Scientist, and relied on data from the products’ inception to December 2007.

From the Mehin study:

A new generation of knee prostheses has been introduced with the intention of improving post-operative knee flexion. In order to evaluate whether this goal has been achieved we performed a systematic review and meta-analysis. Systematic literature searches were conducted on MEDLINE and EMBASE from their inception to December 2007, and proceedings of scientific meetings were also searched. Only randomised, clinical trials were included in the meta-analysis. The mean difference in the maximum post-operative flexion between the ‘high-flex’ and conventional types of prosthesis was defined as the primary outcome measure. A total of five relevant articles was identified. Analysis of these trials suggested that no clinically relevant or statistically significant improvement was obtained in flexion with the ‘high-flex’ prostheses.

If you’re wondering about just how important flexion is, a third publicly available study was published in the November 2009 edition of Orthopedics. Range of Flexion After Primary TKA: The Effect of Soft Tissue Release and Implant Design” was authored by Issaq Ahmed, BEng, MBChB, MRCS; Andrew C. Gray, MD, BSc, MBChB, FRCS(T&O); Marietta van der Linden, PhD; Richard Nutton, MD, FRCS, with their goal to present a “randomized, controlled study was to determine which factors are predictive of postoperative range of flexion.”

According to this study, “preoperative and intraoperative flexion are the best predictors of final ROM, regardless of the degree of soft tissue release and implant design.”

Remarkably, the FDA does not typically require artificial joint manufacturers, like Zimmer, to test its products in actual patients before artificial joints are marketed and sold to unsuspecting patients across the country. As more Zimmer knee defects emerge, perhaps increased attention will be focuses on these issues.

If medical device manufacturers won’t do the right thing and the FDA fails to conduct adequate oversight, it is up to the patients and the public ensure accountability. Device manufacturers should perform all testing required to ensure that products they implant into patients is not defective. Defects in devices like artificial hips, knees and other artificial joints hurt people. We need to make sure it stops.

[More on Zimmer NexGen Artificial Knee Problems]

(c) Copyright 2011 Brett A. Emison

4 Comments

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  1. paula abrams says:
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    I had a TKR on 4/20/10 with a Zimmer NexGen LPS used. I have been in constant pain ever since. I can bend my knee to almost 120 degrees but I can not straighten my leg. I walk with a limp. It is my right knee and even driving is painful. I fired my surgeon because he kept telling me how “wonderful I was doing” and how “great my scar looks”. My scar does look good but I keep complaining because I am in constant pain. I found another knee doctor who did a bone scan which suggested loosening of the prosthesis but a follow up cat scan did not show loosening. The doctors make me feel like I am just a “complainer” but trust me I would not be sitting home everyday icing my knee if I was ok. I actually think I am under complaining. I was given an injection of cortisone last visit but that did not help at all. They say I don’t need pain medicine and I just don’t what to do. I see the FDA has issued a class 2 recall but no one has contacted me. I am exhausted from being in so much pain and I have no idea what I should do. What does a class 2 recall mean? Is there anyone out there with similar complaints?

  2. Thomas McGuire Sr. says:
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    I have a Zimmer flex knee two years this April,so far no problems great feel and mobility. I will keep an eye on all recalls,and hope for the best.

  3. paula abrams says:
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    Well, the good news is I know I am not just a complainer.. My recalled Zimmer NexGen Complete Knee Solution LPS Femoral Component Size E Right is coming out. The bad news is I have to have my knee replaced again. I am really sad that I have to undergo that painful ordeal again. I urge people with Zimmer NexGen knees to use your operative report or implant card (IF you got one) to google the implant by the exact name and find out if yours has been recalled. Since Zimmer denies a problem with the knee, no one will tell you and your surgeon is not required to notify you ( this is my understanding). I found out by myself. So if you have been not able to recover, please do research on the type of implant you have. Save yourself from more pain and agony. The knee doctors don’t like to get involved ( especially if they use Zimmer products) because Zimmer is blaming the doctors technique and or surgical skills. Hopefully once the doctors realize that Zimmer is going to blame them, they will wake up and start taking this very seriously.
    I am concerned about all the people getting these knees everyday, I don’t want be to suffer the way I have. If you are considering and joint replacement – do your homework on the implant suggested. I just trusted my doctor to pick the implant for me based on the activities I liked to do. I bet he can’t say it but I am guessing my original surgeon is not happy with the choice he made either.
    Please self advocate…

  4. Nadia Bobbo says:
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    I have had the “ZIMMER LPS-FLEX”, knee replacement Dec.8th 2009, and have been in unbelievable pain, ever since !!!! My surgeon, recently took ex-rays and blood work, and found nothing, and left me hanging !!! So here I am searching, to see if anyone else, has had the same problem.Even in my sleep, it hurts !!!! I don’t have to do anything strainious, in order, to have pain !!!!To have pain, before, is one thing, but to have total knee replacement and be in so much pain, is a crime !!!!
    Nadia Bobbo