The FDA flagged Signal Medical Corp. for selling a hip implant after making changes that weren’t approved by the federal safety watchdog.

Marysville, Mich.-based Signal Medical makes the MicroSeal total hip acetabular system. In a warning letter sent in December and posted on the FDA’s website this month, the agency said the MicroSeal device includes a hood liner that wasn’t included in the 510(k) filings for the device.

Signal Medical also put additional sizes of the device on the market and changed the shell and liner without clearing the changes with the FDA, according to the letter.

The violations were turned up during an inspection in July and August of last year, the FDA said. The company’s response later in August wasn’t sufficient, the agency said.

"During the close of the inspection, the investigators discussed the observed device design changes to the MicroSeal total hip acetabular system, a 510(k)-cleared device. The 510(k) changes as described above were not covered in your response letter," according to the Dec. 15 warning letter.

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