A hospital has ordered a review into a consultant surgeon who used a new and unproven technique during face and head operations exposing 88 patients to unnecessary risk.
The University Hospital of North Staffordshire NHS Trust (UHNS) said it was reviewing treatment by one of its oral and maxillofacial consultants and had written to the patients affected.
The surgeon had been suspended by the trust since February 2013, pending the outcome of an internal review at the hospital, after concerns were expressed by colleagues.
The trust said it was offering special appointments to former patients who were operated on by the surgeon - who is not being named by the trust - which involved either the treatment of fractures to the lower eye socket or who underwent surgery when "a more conservative, non-surgical approach" should have been tried first .
In independent advice to UHNS investigators, the Royal College of Surgeons (RCS) said: "The patients in the review have at least not been helped, and at worst have come to harm due to the standard of care provided."
It recommended that a wider review of the consultant's practice should be carried out by the trust, which has now been concluded, prompting the contact of former patients.
The consultant was suspended from working at the hospital in Stoke-on-Trent, Staffordshire, after the RCS delivered its opinion.
Robert Courteney-Harris, the hospital's medical director, apologised to those patients affected.
He said: "I should like to express my sincere regret and apologies to any patients who have, or may have, been harmed.
"The trust has a clear protocol in place governing the use of new and unproven procedures and techniques.
"We took immediate action as soon as serious concerns about specific aspects of this consultant's practice were brought to our attention and the consultant has not worked at the trust for more than a year."
Former patients who have been contacted by the trust fall into three categories, including 33 who suffered severe eye socket damage and were then operated on by the consultant using an artificial bone substitute which in some cases could have led to excess scarring.
The RCS review said the use of the bone substitute was "a new technique diverging from current standard practice" and therefore the trust's own protocols and National Institute for Clinical Excellence guidelines should have been adhered to.
A further 19 patients may have undergone potentially unnecessary eye socket surgery, while the remaining 36 patients could have had operations on their jaw joint when a more conservative approach should have been adopted, in line with recommendations from the British Association of Oral and Maxillofacial Surgeons.
Mr Courteney-Harris said the process of confirming whether actual or potential harm had been caused, over and above the natural consequences of disease or the normal complications of surgery, was "a difficult and complex decision".
He added: "I should like to reassure patients who have been invited to attend a review that they will have a thorough assessment by one of our highly experienced oral and maxillofacial consultants of their past treatment and any possible side-effects or complications.
"I would strongly urge all patients who have been invited for review to attend their appointment during which they will be given a full explanation of their past care and treatment.
"Their questions will be answered honestly and openly and options for those patients who may require further treatment will be fully discussed with them."