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Zimmer NextGen Knee Replacement

The Device

The Zimmer Nex-Gen Flex Knee Replacement is a medical device used to cap the femur and tibia at the knee. Unlike the more common implanting method, which requires using a traditional adhesive cement to bond thigh bone and implant, the Zimmer device was designed with a porous fiber metal coating facilitating attachment via natural bone growth into the device. The postulated advantage of such a design is greater longevity of the device by circumventing the issue of cement, and its propensity to break down over time.

Since the release of the device in 2003, Zimmer has reported sales of over 150,000 of the devices. In 2009, these sales represented 2% of their $1.76 billion in sales.

The Controversy

While the device continues to remain on the market, questions about its safety and effectiveness have begun to surface. In 2010, a former Zimmer consultant and orthopedic surgeon at Rush University Medical Institute delivered a presentation to the American Academy of Orthopedic Surgeons, detailing his disturbing findings about the effectiveness of the device. Their data revealed that one year post surgery, 9% of patients required revision surgery, while another 36% demonstrated signs of loosening indicating potential impending failure. Furthermore these patients reported an uncommon level of pain relating to the new knee. Not surprisingly, the authors concluded their report by stating, “[T]his component is still commercially available but should not be used for any patient.”

Since the report by Dr. Berger, a multitude of supporting research has been published echoing concerns that the device is inherently unsafe. These reports have included studies done in Korea[1,2] as well as the United States[3].​


Symptoms of a defective Zimmer Nex-Gen CR Flex Knee replacement include

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Loosening of replacement knees
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Unexplained pain after knee replacement
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Knee stiffness, or constant pain in the knee
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Trouble placing weight on the knee
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Diminished joint movement

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