Because of reported cases of Zimmer Persona knee problems like gaps between bone and components—otherwise known as poor seating—and overall loosening, the Zimmer company made the decision to voluntarily initiate a recall of its trabecular metal (TM) tibial plate implant in the spring of 2015.

Recipients of this Zimmer total knee replacement (TKR) part had reported a host of symptoms which led them back to their orthopedic physician for further consult.

According to the Hospital for Special Surgery’s website, a properly functioning prosthetic knee joint implant is dependent upon proper fixation to the bone. Some surgeons prefer components that are cemented into the bone and other surgeons prefer non-cemented varieties which depend on in-growth into the bone for stability of the unit.

The tibial plate of the Zimmer Persona system is in the latter category. The Zimmer TM tibial plate acts as a flat surface which the upper joint component “rocks” upon. The plate uses two pegs that insert into the lower leg bone, where they are expected to connect directly with the tissue.

Radiological Evidence

When former TKR patients would experience Zimmer Persona knee problems, a variety of experiences were reported. Among them but not to the exclusion of other symptoms were chronic pain and swelling in the joint area, loss of range of motion or complete mobility, and joint tightness or feeling like it was going to “give out.”

When X-rays were taken of the prosthetic unit, diagnostic evidence displayed radiolucent lines which were interpreted as gaps between the plate and the bone. The gaps are indicative of the implanted tibial surface moving from its initial surgically placed position. This movement meant that the component was loosening and eventually would result in prosthetic failure.

When a first prosthetic fails in a total hip arthroplasty, according to the Livestrong website, a patient may require revision joint surgery. Prior to revision surgery, X-rays and more detailed diagnostic procedures such as MRIs and CT scans often are performed ahead of time. This is to assess the amount and location of bone tissue that has been lost. If infection is suspected, aspiration of fluid will be drawn off and analyzed prior to surgery as well.

Knee revision surgery poses a higher risk profile to the patient because of the danger that a new replacement prosthetic will not adhere properly if a significant amount of bone tissue has been lost. It also presents the typical risks of general anesthesia and the possible formation of blood clots associated with such an invasive surgery.

The Recall

The voluntary recall was followed up and assisted by the U.S. Food and Drug Administration (FDA) in March 2015. It affected 12,000 units. The recall does little to help those who experienced Zimmer Persona knee problems between 2012 and 2015 and were subject to corrective knee revision surgeries that were costly and required time off of work to heal.