WASHINGTON  The Food and Drug Administration said Thursday that it would rescind the approval of a patch for injured knees that it granted in error in 2008 after being unduly pressured by four New Jersey congressmen and its own commissioner.

The patch, known as Menaflex and manufactured by ReGen Biologics, was so different from earlier devices that it should have been tested far more thoroughly before approval, officials determined.

“We are concluding that the science does not support a decision to clear the device, and therefore we’ll move forward to rescind” its approval, Dr. Jeffrey E. Shuren, director of the F.D.A.’s device center, said in an interview.

The F.D.A. had never before admitted that it approved a drug or device mistakenly, never rescinded such an approval without citing new information about the product, never admitted that a regulatory decision was influenced by politics, and never accused a former commissioner of questionable conduct.