The Food and Drug Administration [has admitted] that four New Jersey congressmen and its own former commissioner unduly influenced the process that led to its decision last year to approve a patch for injured knees. The agency's scientific reviewers repeatedly and unanimously over many years decided that the device, known as Menaflex and manufactured by ReGen Biologics Inc., was unsafe because the device often failed, forcing patients to get another operation. But after receiving what an F.D.A. report described as extreme," "unusual" and persistent pressure from four Democrats from New Jersey ... agency managers overruled the scientists and approved the device for sale in December. All four legislators made their inquiries within a few months of receiving significant campaign contributions from ReGen, which is based in New Jersey, but all said they had acted appropriately and were not influenced by the money. Dr. Andrew C. von Eschenbach, the former drug agency's commissioner, said he had acted properly. The agency has never before publicly questioned the process behind one of its approvals, never admitted that a regulatory decision was influenced by politics, and never accused a former commissioner of questionable conduct. The report, written by top agency officials, said that Dr. von Eschenbach, who resigned as F.D.A. commissioner in January, became as a result of political pressure "personally engaged in the details of a process usually coordinated" by scientific staff. One agency manager concluded that Dr. von Eschenbach "was demanding not only an expedited process but also an outcome in favor of ReGen," the report stated.