Knee implants you thought would last decades may only last 3 years.

Today’s post comes from guest author Brenda Fulmer from Pasternack Tilker Ziegler Walsh Stanton & Romano.

Zimmer is an international medical device manufacturer based in northern Indiana. It was founded in 1927, and focuses on the manufacture of products for orthopaedic surgeries. Zimmer’s sales in 2009 were $1.76 billion, and it is estimated that the NexGen family of knee implants make up about 2% of the overall sales of Zimmer.

Flex implants are not lasting nearly as long as intended.

The Zimmer NexGen Knee Implant is not a specific device, but rather a family of devices. Within this NexGen device family, there are different models of implants: NexGen CR-Flex, NexGen LPS-Flex, NexGen High Flex, NexGen LPS, NexGen MIS.

Unlike most knee implants, the Zimmer NexGen CR-Flex is attached without the use of cement, which may cause the system to loosen or detach completely.

The Zimmer NexGen CR-Flex implant was designed to give patients better range of motion than the customary NexGen device. Scientific studies have been accumulating for years with regard to concerns over the safety of the NexGen CR-Flex. Interestingly, the U.S.Food and Drug Administration did not make it a requirement for Zimmer to test the NexGen CR-Flex artificial knee implant system in patients prior to putting it on the market.

Knee replacements are intended to last approximately 15 years, but studies have shown the Zimmer NexGen CR-Flex can fail within 3 years of the initial knee implant surgery. 

Recently, Dr. Berger, who worked on designing surgical tools and artificial joints for Zimmer, published the following results from a study demonstrating that the Zimmer NexGen CR-Flex implants are not lasting nearly as long as intended:

  • In 2005, Dr. Berger, implanted the NexGen CR-Flex products in 125 patients. Within a year after implantation, these patients reported unusual pain associated with their NexGen CR-Flex knee implants. In 2006, Dr. Berger began noting evidence that the Zimmer knee implants were failing in his patients when X-rays showed evidence of loosening and failure of the implant. Several of his patients underwent revision surgeries that year due to failure of their knee implants.
  • Drs. Della Valle and Berger in March of 2010, presented the results of their study at an American Academy of Orthopaedic Surgeons Conference which noted that 9% of the patients in the study required a revision surgery due to failure of their knee implant, and that the complication rate might be as high as 36% when patients had signs and symptoms of loosening and failure of their implants, but had not yet undergone a revision surgery. In light of their research findings, Dr. Berger recommended that the NexGen CR-Flex not be used in patients in the future.

It is believed that high failure rates of the high-flex models of Zimmer knee implants may be due to a defective design, but Zimmer has placed the blame on surgeons.

Unlike most artificial knee implants, the Zimmer NexGen CR-Flex is attached to the thigh bone without the use of cement. Regrettably, this may cause the knee replacement system to loosen over time or detach completely. A loose knee implant can cause pain, erode the bone, and severely restrict the patient’s daily activities.

Signs of a loose Zimmer knee implant may include the following:

  • decreased range of motion in the joint;
  • difficulty putting weight on the knee;
  • knee stiffness;
  • knee pain; and
  • limping.

Knee replacements are intended to last approximately 15 years, but studies have shown the Zimmer NexGen CR-Flex can fail within three years of the initial knee implant surgery. Because the Zimmer NexGen CR-Flex knee replacements are linked to high failure rates, some doctors have requested a recall. So far, however, these Zimmer knee implants have not been recalled. It is believed that high failure rates of the high-flex models of Zimmer knee implants may be due to a defective design, but Zimmer has placed the blame on surgeons.

Brenda Fulmer is a shareholder at the law firm Searcy Denney Scarola Barnhart & Shipley in West Palm Beach and partners with Pasternack Tilker Ziegler Walsh Stanton & Romano in the litigation of drug and pharmaceutical mass tort cases. Ms. Fulmer graduated from the University of South Florida with a B.S. in Finance, and received her Juris Doctor degree cum laude from Stetson University College of Law. For the past 17 years, she has represented thousands of mass torts plaintiffs in both state and federal courts who have been injured by defective medical devices and drugs.