It was down to plastic surgeons to warn women of potential dangers from PIP breast implants, the head of the medicines regulator has said.
Professor Sir Kent Woods, chief executive of the Medicines and Healthcare products Regulatory Agency (MHRA), defended the regulator's actions in the lead up to the PIP breast implant scandal.
He told the Commons Health Committee the MHRA's actions had been "appropriate" but it had been unable to communicate directly with affected patients because it did not have their identity data.
Around 40,000 women in the UK received implants manufactured by the now closed French company Poly Implant Prostheses (PIP), with around 5% of operations carried out on the NHS and the rest in private UK clinics.
The implants were filled with non-medical grade silicone intended for use in mattresses.
Professor Woods said the MHRA had acted in March 2010 and told surgeons not to implant the devices following an alert from French authorities that they were filled with unauthorised silicone.
He said providers had to show they had complied with medical device alerts, although it was less clear whether this happened in the private sector.
"That system certainly runs throughout the NHS. I think penetration into the private sector is less certain. I would say the other route we took was through the professional surgical associations to ensure that these practitioners who are using the implants would have that information immediately."
Asked if he was "absolutely confident" no PIP implants had been put in after the March 2010 alert, Professor Woods said: "I'm afraid I can't give you that assurance.
"I can only say we used every route available to us to get the information out to where it was needed but I can't say that no PIP implant was removed from store into an operating theatre after that date."
Labour MP Barbara Keeley asked him why the MHRA had not communicated directly with patients on the potential dangers of the implants.
He replied: "We are not in a position to do that because we don't have the identity of the patients.
"We do use all the routes available to us, we put out press releases, we put out medical device alerts, we have contacted professional associations."
He said the same process was used to alert health professionals to concerns over PIP implants in both March 2010 and last December.
But the difference was media interest in the story rose in the latter months of last year.
"We can only go through the general media and through the profession," he added.
"There's no other route available to us. We made every effort to put appropriate information out at the time."
Professor Woods agreed it was up to health professionals to communicate directly with patients but said there was no data available on whether that had actually happened.
"The responsibility sits with the healthcare professional who's carried out the procedure to take responsibility for follow-up and I don't think this is a responsibility that can be moved elsewhere to be honest."
Professor Woods said the MHRA would like to see a national registry system for breast implants to be able to identify and track patients in the future, something being considered by the current Government review of the industry.
Simon Withey, from the British Association of Aesthetic Plastic Surgeons (BAAPS) added: "There's a huge variability both in record keeping and levels of professional responsibility - forgetting the NHS - across the private sector.
"There are individual clinicians who are clearly responsible and keep a close eye on what they are doing and there are larger, more commercial organisations where the clinician is perhaps distanced from the executive decisions made and perhaps as a result doesn't feel quite as responsible in some cases."
Professor Sir Bruce Keogh, NHS medical director, told the committee around 1,000 private patients with PIP implants have contacted the NHS.
The NHS has said women who cannot get redress from private clinics can have their implants removed on the NHS.
Professor Keogh also said 745 NHS patients with PIP implants had so far been identified.