Zimmer NexGen Knee Replacement

zimmer nexgen knee replacement

Zimmer Holdings, Inc. is an Indiana base orthopedics company.  They manufacture medical products including joint and skeletal replacement systems and surgical tools as well as biologics designed to assist in joint replacement surgeries.

Zimmer reported 2011 sales of over $4.4 billion, with $2.4 of that attributed to the Americas.  Knee implant products provide the bulk of revenue with worldwide sales of $1.82 million.  They are the largest knee implant manufacturer in the world with a 26 percent share of the worldwide knee implant market.

Zimmer developed its first non-hinged total knee replacement device in 1968 and followed in 1973 with a metal-plastic total knee product.  The NexGen devices were introduced in 1995 with the Next Generation Complete Knee Solution System.  This was followed by a number of NexGen, High Flex devices which were intended to increase range of motion over that of other devices on the market.

Despite its intent to improve the knee implant market, several of the NexGen products are the subject of multiple lawsuits due to a high rate of revision surgery required from failing implants.

Zimmer announced acquisition of another joint replacement device company, Biomet in April of 2014 for $13.35 billion which will make Zimmer the second largest orthopedics manufacturer in the US once the sale is finalized.

Design of Zimmer Knee Replacement Products

Zimmer manufactures a number of knee replacement devices including total knee systems, unicompartmental systems, femoral, tibial and patellar implants, and cemented and non-cemented components. They also manufacture gender-specific knee systems and components that are designed to closer mimic the female anatomy.

The NexGen system is one of the implant manufacturer’s main product lines.  It originally offered 120 degrees of flexion which is the closest that manufacturers were able to get to the natural knee flexion of 160 degrees.

The Food and Drug Administration approved the NexGen LPS-Flex Fixed-Bearing Knee in 1999 which offered 155 degrees of flexion.  The device was approved through the shorter 510(k) approval process, which allows the manufacturer to be exempt from the normal Premarket Approval (PMA) application process.  The PMA process requires that manufacturers submit data from clinical studies performed in humans that prove efficacy and safety.

The 510(k) process allows the manufacturers to avoid costly and lengthy clinical trials by claiming that the device is substantially similar to a device that is already on the US market.  The PMA process may have identified future failure potential in clinical studies that the 510(k) process did not  identify. 510(k) approvals require only post-market surveillance which is based largely on voluntary reports of adverse events.

The NexGen line was reportedly to be the first of its kind by Zimmer and was marketed towards younger and more active patients along with those whose cultural backgrounds, religious beliefs or employment required extensive kneeling for prayers or spending a good deal of time on the knees.

Zimmer Knee Replacement Complications

The original Zimmer knee replacement products had a normal revision rate and were quite reliable.  The original design was quite stiff, only offering the normal 120 degrees of flexion.  Subsequent products were intended to offer 155 degrees of flexion but were approved through the 510(k) process and were not required to be tested.  Patients who received these products were implanted with an unproven and untested device.

There are three systems that have been under scrutiny due to side effects and failure. These systems include the NexGen Cruciate Retaining Flex (CR-Flex), NexGen Lateral Posterior Stabilization Flex (LPS-Flex), and the NexGen Minimally Invasive Solutions (MIS) Tibial Component.

Zimmer Knee replacement side effects are mild in most cases but can be serious in others and likely require knee revision surgery due to failure.

  • Bruising and swelling of the knee
  • Severe pain in the knee
  • Poor motion or stiffness of the knee

Mild side effects may resolve but may become permanent.

More severe effects of Zimmer knee replacement focus mainly around dislocation and loosening of the component from natural bone.  These will often require revision surgery and include

  • Persistent or increasing knee pain
  • Nerve and blood vessel damage which may be permanent
  • Knee replacement failure resulting in dislocation and severe pain
  • Periprosthetic fractures in bone surrounding the implant

Other patients may also experience events which are rarer in Zimmer knee replacement products but are also severe and may require knee revision such as:

  • Infection with fever or chills
  • Blood clots creating pain in the lower leg
  • Particle shedding from device structure that is deposited into surrounding tissue
  • Osteolysis or necrosis (bone dissolution or tissue death) caused by shed particles

Zimmer NexGen Knee Replacement Recalls and Lawsuits

Zimmer, along with three other device manufacturers agreed to pay $310 million in fines and penalties regarding claims that they paid kickbacks to surgeons for the use of their devices in 2007.  Several of the NexGen Devices have been recalled due to high failure rates, mostly related to unseating of the device implants resulting in revision surgery.

In April of 2010 Zimmer issued a safety letter regarding the high failure rate of theNexGen MIS Tibial Component urging physicians to disregard instructions for implanting of the device and conducted a relabeling campaign.  In September of 2010, this action was classified by the FDA as part of a Class II recall.  Already 68,000 components had already been implanted in patients in the US.

Another product, not part of the NexGen line, the Natural-Knee II Durasel Patella was originally manufactured by Sulzer Medica, acquired by Zimmer was also recalled by the FDA as part of a Class II recall.  The Natural-Knee product will be separate to any litigation regarding NexGen products.

Sulzer had previously paid $1 billion to settle lawsuits for some of its other implants and the Natural-Knee component had already been implanted in 110,000 US patients.

Products facing recall and lawsuits include:

  • NexGen MIS Tibial Components
  • NexGen TM Tibial Trays
  • NexGen LPS-Flex GSF Femoral Component
  • NexGen MIS Modular Tibial Plates and Keels
  • Natural-Knee II Durasel Patella

Zimmer is currently facing over 1300 lawsuits regarding failed knee implants.  Federal lawsuits regarding Zimmer NexGen implants have been consolidated in multidistrict legislation (MDL) in the US District Court of Northern Illinois overseen by Judge Rebecca Pallmeyer.  The first bellweather trial involving six cases has been set for February of 2015.

Multiple rounds of additional lawsuits are expected in both federal and state courts.

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