“The Most Anatomically Accurate Knee Implant”
In 2012, medical device manufacturer Zimmer, Inc. introduced the Persona artificial knee to the public with lofty language. Zimmer announced that the company was “redefining knee arthroplasty and ushering in a new era of personalization with the introduction of the Persona Knee.” Zimmer stated on its website that by “working with more than 50 of the world’s most respected orthopaedic surgeons, and utilizing analytics from both genders and 1,500 different bone types from 26 different ethnicities, Zimmer was able to create the most anatomically accurate knee implant.”
The reported advantage of the Persona knee system, according to Zimmer, was that it would give surgeons several component options for each patient and each surgery, thus assuring a tailored fit for the patient. Again, from Zimmer: “the result is an implant system that addresses the unique needs of the patient and accommodates surgeon-specific preferences — all while empowering surgeons to minimize “trade-offs” and better optimize results.” Sounds great, doesn’t it?
Zimmer sold the Persona knee from November 2012 through March 2015. A lot of them. But bad things began to happen. People began reporting pain and other symptoms, including loosening of the knee components inside the leg.
The Zimmer Persona Knee Recall
In March 2015, Zimmer, Inc. issued a voluntary recall of the Persona Knee. The actual recalled component was the Persona Trabecular Metal Tibial Plate. Zimmer sent an “Urgent Medical Device Recall” letter to surgeons and risk managers, and then notified the Food and Drug Administration. The FDA announced the recall on its website:
“Zimmer Inc. is initiating a voluntary recall of Persona Trabecular Metal Tibial following an increase in complaints of radiolucent lines and loosening. All sizes and lots of the affected devices are being removed from distribution. Urgent Medical Device Recall notices were issued to affected distributors, hospitals, and surgeons on 2/16/2015 via mail. Customers are asked to review the notification and ensure affected personnel are aware of the contents. All affected product are to be located and quarantined immediately. The Inventory Return Certification Form should be completed and returned along with the recalled product. Customers may contact the following with any questions: 1-877-946-2761 between 8:00 am and 5:00pm EST.”
Note: For readers in the Carolinas, the recall impacts North Carolina but not South Carolina. Plainly, the Zimmer Persona knee was marketed, sold, and implanted in North Carolina (and many other states).
What Are Radiolucent Lines?
Radiolucent lines are spaces between the artificial knee component and the bone. Essentially, small gaps occur because the medical device is not implanted tightly or securely to the bone. These spaces can cause serious problems for a patient with an artificial knee, and can be the first signs of an artificial knee failure. The lines or spaces can fill with fluid or tissue and can cause additional loosening of the medical device.
The actual definition of “radiolucent” is that open space which is visible on an X-ray, one which shows an opening or gap where an opening or gap should not be visible.
What is Loosening?
Loosening is when the artificial knee begins to move in the patient’s leg and separate from the bone. This is a bad thing. Loosening can be very painful. A loose artificial knee will cause major complications and eventually the need for replacement and revision surgery.
Some of the physical symptoms of a failure of an artificial knee include pain, stiffness, swelling, and instability in the leg or around the knee.
Persona Knee Was Approved Through the Dreaded 510(K) Process
Like many of the metal-on-metal artificial hips entering the market in the last ten to fifteen years, the Zimmer Persona artificial knee bypassed the normal and vital pre-market testing for new medical products through a process known as “510(k).” I have written about this problematic loophole often on this site. The 510(k) process allows a manufacturer to notify the Food and Drug Administration under section 510(k) of the Medical Device Amendments Act of 1976 (MDA) of its intent to market a device (like the Persona knee) and to describe the new device’s “substantial equivalence” to a pre-MDA device. The FDA may then approve the new device for sale in the United States without rigorous testing as is required for new medical devices. This is how the Persona Knee reached the market.
The recall of the Zimmer Persona Knee currently impacts as many as 11,658 patients (this is the “quantity in commerce” as of March 2015). This latest potential mass failure of a medical device is a very recent development, and no multidistrict litigation (MDL) court has been chosen. But it will, and likely soon. For more information on MDLs, check out my article:
If you received an artificial knee on or after November 2012 and have developed pain or other symptoms in the knee or leg, you should have received a recall letter directly from Zimmer, Inc. But even if you did not receive this letter, you should confirm with your surgeon whether the Zimmer Persona Knee was implanted. And keep a close watch on your artificial knee.