Hintermann Series H3 Total Ankle Replacement Failure Warning Issued by FDA

Federal regulators are warning doctors and patients that Hintermann Series H3 ankle implants have a “higher-than-expected” risk of failure, which can lead to the need for additional surgeries, including replacement of the device.

The Hintermann Series H3 Total Ankle Replacement (TAR) warning was issued by the U.S. Food and Drug Administration (FDA) on February 29, after real-world data suggested that the implants have an overall 16.1% failure rate.

The Hintermann TAR was approved by the FDA in 2019, and is designed to be used as a prosthetic replacement for ankle joints suffering from osteoarthritis, post-traumatic osteoarthritis and rheumatoid arthritis. The implant consists of a metal plate in the lower leg, a mobile plastic component and a metal ankle implant.

At the time of the Hintermann TAR’s approval, the FDA required the manufacturer to conduct two post-approval studies. One was a long-term 10-year follow-up involving 298 patients, and the other was a five-year follow-up.

High Number of Hintermann Ankle Implant Failures

According to the FDA safety communication, data from post-approval studies (PAS) has indicated that 16.1% of patients who receive the ankle implant require additional surgery, including removals or revisions of metal components due to failure. This compares to just 9.9% the manufacturer reported during premarket clinical trials.

“When all types of revisions are included in the interim PAS results (such as revisions of the plastic component as well as the metal component), the rate of additional surgery is at least 28.5%,” the FDA warning indicates. “The FDA is working with the manufacturer to evaluate data from all available sources to better understand potential causes of the higher failure rate.”

The Hintermann ankle implant is one of only two mobile-bearing TARs approved for use by the agency, with the other being the Scandinavian Total Ankle Replacement device known as the STAR ankle, approved in 2009.

The FDA issued a similar safety communication about problems with STAR ankle implants in 2021, warning about a higher risk of ankle replacement failure linked to the plastic components of the implant breaking.

FDA Hintermann Ankle Implant Recommendations

In the new warning, the FDA is recommending that patients considering receiving a Hintermann Series H3 TAR system should discuss all available treatment options with their doctor, and should know the benefits and risks associated with all joint replacement implants and procedures.

Those who already have the implant do not need to have it removed, as long as the system is functioning properly and there is no new or worsening pain or symptoms, the FDA notes.

However, recipients of the implant should contact their health care provider immediately if they suffer new or worsening pain or swelling, an inability to use their ankle or bear their weight, grinding or other nose, or weakness around the implanted device.

The FDA recommends doctors review and discuss these recommendations with their patients before deciding to undergo the procedure, including treatment options, risks and benefits. They should also carefully read and follow the system’s instructions, monitor patients who receive the Hintermann TAR ankle implant for signs of device problems, such as loosening and fracturing of the implant components, and should perform X-rays when a device problem is suspected.

However, the agency warns that X-ray results may be negative even if a polyethylene fracture is suspected, and recommends following up with CT scans if the X-rays show no sign of damage but problems persist. The agency notes that fractures in plastic materials, such as the polyethylene used in the implants, can also be hard to detect on a CT scan.

The FDA indicates it is continuing to work with the manufacturer to determine the cause of the failures and will keep the public informed of any new, significant information.

The agency urges health care professionals and patients who experience problems with the Hintermann Series H3 TAR to file a report through the FDA’s MedWatch adverse event reporting system.