There are two major bones in the lower leg: the tibia and fibula. The tibia, larger of the two bones, articulates with the femur to form the knee joint.

In total knee replacements, the prosthetic units come with a femoral component and a tibial component which replace or add to the surface of the existing bones where they meet at the knee.

In the case of the Zimmer Persona knee replacement device, a larger-than-expected number of reports of Zimmer tibial plate failure which led to its 2015 recall.

The Zimmer trabecular metal (TM) tibial plate was the tibial component of the Zimmer Persona prosthetic unit. To function, it was added to the surface of the larger bone of the lower leg via the surgical insertion of two pegs located on its underside.

Knee Replacement Design

Unlike many of the tibial components on the market, the TM tibial plate made by Zimmer is reliant upon the growth of bone tissue around these pegs to provide stability. In other words, the pegs and component were not adhered to the bone with surgical cement.

Other designs of knee replacement components would often use one peg and surgical glue to ensure a stable surface for the rocking motion of the femoral piece during ambulation. While the idea behind the Persona was theoretically to provide greater stability, high instances of Zimmer tibial plate failure were reportedly leading to the need for early revision surgery.

According to reported problems, the Zimmer tibial plate failure was first experienced by a prosthetic recipient as localized pain and inflammation. This pain was constant in many and frequently debilitating.

If the pain was not preventative of movement, patients would often report an overall sense of instability, as if the joint would give way while walking.

Upon further diagnostic workup, the cause of the Zimmer tibial plate failure was blamed on spaces that grew between the TM tibial plate and the bone. The spaces, known as radiolucent lines, are visible on X-ray.

The lines were a sign that the plate had moved from its original position as placed during surgery and had become unstable. With these lines visible, replacement of the prosthetic unit may be necessary.

Approval and Recall of the Zimmer Persona System

The Persona knee system was first introduced by the Zimmer Co. of Warsaw, Ind. in March 2013. The Persona knee prosthetic system came with instrumentation that, according to an online article at news-medical.net, allowed for precise surgical placement by the orthopedic team that was completely personalized for the specific patient involved.

It was intended to be a breakthrough in technology, until reports of Zimmer tibial plate failure indicated possible design difficulties.

When reports of these problems got to a certain level, the Zimmer Co. initiated a voluntary recall in January 2015. This recall was announced by the U.S. Food and Drug Administration in March 2015. The FDA formal recall affected 11,658 units distributed in the U.S. and globally.

If you or a loved one has experienced an early knee revision with all its risks and complications secondary to Zimmer tibial plate failure, you may be entitled to compensation. Medical device product liability lawyers are available for consultation to see if a knee replacement lawsuit is an option for you.