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Knee Implants


Biomet M2a Magnum Hip Implant

Recall Information

All About Knee Replacement Systems

Knee replacement surgery, also referred to as arthroplasty, is a surgical procedure to resurface a knee damaged by arthritis or severely impaired due to an injury. Metal and plastic parts are used to cap the ends of the bones that form the knee joint, along with the kneecap.

There are several kinds of arthritis that can affect the normal functioning of the knee and cause varying levels of pain:

The goal of knee replacement surgery is to relieve knee pain that cannot be controlled by other treatments and to allow the patient to return to his or her normal activities.

Knee Replacement Surgical Methods

There are four types of knee replacement surgeries: total , partial , kneecap and complex (or revision). The most common type of surgery is total knee replacement.

Total knee replacement systems are comprised of four parts:

The major manufacturers of knee replacement systems include Zimmer Biomet, DePuy Synthes (a division of Johnson & Johnson), Smith & Nephew, Stryker and Wright Medical Group. Each manufacturer markets several different models of knee replacement systems in the U.S. and abroad. These devices and their individual components can be made from metal, ceramics, strong plastics and other materials.

When Knee Replacement Systems Are Defective

As per 2017 Wolters Kluwer data, over 700,000 knee replacement surgeries were performed annually in the U.S., and projected to grow to 3.8 million by 2030. While the majority of knee replacement surgeries have positive results for the patient, they sometimes go horribly wrong due to a knee replacement system that is defective in design and/or manufacture.  When a faulty implant has been used in surgery, it often fails prematurely and causes injury to the patient. The only solution is for the patient to undergo revision surgery—the bad implant is removed and replaced by another device.  Unfortunately, the defective device causes irreversible injury and disability to the patient. And, costly revision surgery is complex, requires longer recovery and cannot always repair the damage caused by the bad implant.

Symptoms of a Defective Knee Implant

Signs of a defective knee implant include:

Protect Yourself

If you are considering a knee replacement, ask your surgeon whether the device he or she is planning to use has ever been recalled. Also ask for the unique device identifier for your implant in case it is recalled in the future. You can research knee replacement systems by visiting the FDA’s website as well as other sources online.  Be aware, the FDA’s list of recalls may not include implants that were recalled by the manufacturers themselves. And, do not assume your surgeon is in the know about every defective implant.

Also, make sure you don’t have an allergy or a sensitivity to any of the materials in your device and that your surgeon isn’t planning to use a metal-on-metal implant.

Avoid Metal-on-Metal Knee Implants

As with metal-on-metal (MoM) hip implants, there is increasing concern about the use of MoM knee replacement systems.  When the components of these systems rub against each other, they can release metal ions and debris in the bloodstream.

In late 2016, a study published in Acta Orthopaedica, the Official Publication of the Nordic Orthopedic Federation, reported that MoM total knee replacements carry a high risk of increased levels of metal ions and adverse reactions to metal debris and lead to complicated revision surgery. For example, 19 of 22 MoM patients had over 5ppb of chromium as compared to 1 of 12 patients in the non MoM group;  11 of the 22 MoM patients had chromium levels over 5ppb compared to none of the 12 patients in the non MoM group.

“In summary, our results clearly show that this MoM hinge TKA carries a high risk of having elevated levels of systemic metal ions and local ARMD, leading to complicated knee revisions. Thus, we strongly discourage the use of MoM hinge TKA, as there are safer options available.”

Knee Replacement Implants to Watch

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Medical Device Watch is sponsored by Wilentz, Goldman & Spitzer, P.A. The medical device approval process in the U.S. allows for the sale of some devices that have not been tested in clinical trials on humans. Our goal is to help people protect themselves from the physical, emotional and financial harm that can be caused by medical devices that are defective.


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