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.
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
Loosening of replacement knees
Unexplained pain after knee replacement
Knee stiffness, or constant pain in the knee
Trouble placing weight on the knee
Diminished joint movement
As a result of these defects, many devices may require revision surgery to correct complications associated with looseness and device migration. Others may require replacing the device with a more effective and reliable model.
If you believe you or a loved one have a defective knee implant, please contact Freese & Goss today.
[1] Han H, Kang, B, Yoon, K. “High Incidence of Loosening of the Femoral Component in Legacy Posterior Stabilised-Flex Total Knee Replacement.” J. Bone & Joint Surg Br. 89-B(11). 1457-1461.
[2] Cho S, Youm Y, Park K. “Three- to Six-Year Follow-Up Results after High-Flexion Total Knee Arthroplasty: Can we Allow Passive Deep Knee Bending.” Knee Surg Sports Traumatol Arthrosc. July, 2010.
[3] Foran J, Whited B, Sporer S. “Early Aseptic Loosening with a Precoated Low-Profile Tibial Component.” J Arthroplasty. Article in Press, 2010.
