Synovo Total Hip Systems Have Not Been Sufficiently Tested, FDA Warns

Federal regulators are warning health care professionals to avoid certain artificial hip implants manufactured by Synovo Production, Inc., which may fail and cause further complications for hip replacement surgery patients.

In a letter issued to medical providers on January 3, the U.S. Food and Drug Administration (FDA) indicates the design of the Synovo Total Hip Replacement System and its components have been significantly modified from those originally approved by the agency. The systems were then distributed with significant changes, without the proper premarket approval, the agency warns.

The hip implant system is used to perform total joint replacement surgeries, and contains at least three resurfacing implant components, including the Femoral Resurfacing Cup, the Acetabular Fixation Cup, and the Acetabular Bearing. The Femoral Resurfacing Cup is a metal shell that is placed over the top part of the femur, after the thigh bone is trimmed, and can used as a component of the system or as a stand-alone product in hip reconstruction procedures. The Acetabular Fixation Cup and Acetabular Bearing can also be used separately from the system, along with a conventional femoral stem and head component, to replace where the pelvic socket and thigh bone join together to form the hip joint.

The FDA warns that the artificial hip implant system, and its resurfacing implant components, have not been reviewed or approved by the FDA to confirm they are safe or effective. The FDA indicates the changes made to the devices may increase the risk of the components loosening. This can lead to breaks in the component, complete device failure, bone loss, and fractures, which will require revision surgery.

Synovo Investigation and Warning Letter

The FDA issued an earlier warning letter to Synovo on March 23, 2023, after investigators found several production, marketing, and distribution violations during an onsite inspection of the manufacturing facility. They also found Synovo failed to perform annual quality inspections, did not document employee training, and failed to submit annual registration to develop, manufacture, or distribute medical devices, as required.

In the letter, the FDA indicates that the Femoral Resurfacing Cup design, components, and manufacturing methods were significantly changed from the “Modified New Jersey Femoral Hip Resurfacing Component,” which was approved by the agency on May 23, 1991. Synovo replaced the porous underside coating of the component with cement-less, titanium coating in April 2020, and distributed the modified devices without documentation or proper premarket approval.

After changing the coating, Synovo found an issue with the new titanium material adhering to the implant, and believed the problem stemmed from the second machining process, the FDA indicates. It then discontinued the procedure, without documenting the modification or notifying the agency as required. It also failed to verify the manufacturing change was effective in correcting the delamination issue, according to FDA officials.

The warning also indicated the manufacturer produced three Femoral Resurfacing Cups with shortened stems in July 2022, at the request of a surgeon. Synovo failed to document the design changes and failed to verify the changes met product specifications.

Synovo was warned to immediately stop manufacturing the hip implant system and its components. The manufacturer was also required to submit a written response to the agency within fifteen business days, documenting the specific steps it would take to address the violations and prevent further violations, as well as a timeline for when it expected to implement them.

FDA Synovo Hip System Recommendations

The FDA recommends that health care providers avoid purchasing the currently available Synovo Total Hip System, remove any systems or components from inventory, and consider alternative hip replacement implant devices for hip replacement surgeries.

Patients who received the implants after 2019 have the greatest risk of experiencing complications from implant component loosening. Medical professionals should closely monitor them for potential bone loss, device loosening or failure. However, the FDA does not recommend that the system be removed unless the device shows signs of failure, or the patient experiences new or worsening symptoms.

Recipients of Synovo hip implant devices should contact their health care provider if their implant is not functioning properly, or if they experience worsening pain, inability to bear weight, weakness of the hip or knee, or grinding noises.

Consumers and health care professionals may forward questions to the Division of Industry and Consumer Education (DICE) by email at DICE@FDA.HHS.GOV, or phone at 800-638-2041 or 301-796-7100.

The FDA also encourages consumers to report any problems they experience with the Synovo implants to the MedWatch Adverse Event Reporting Program.