Bupa has hit back at surgeons by denying claims that its medical review process could be "potentially harmful to patients" and said it has consulted with practitioner bodies.
The private medical insurance (PMI) provider insisted that it was not taking a decision on whether the clinical treatment took place or not, only towards funding of the procedure.
In an open letter to members on the British Orthopaedic Association (BOA) website, the body claimed Bupa was planning to introduce a second opinion review process to decide whether arthroscopic knee surgery would be funded.
The letter was also signed by the British Association for Surgery of the Knee (BASK) and the Federation of Independent Practitioner Organisations (FIPO) and openly criticised those details of Bupa's plan it discussed.
However, Bupa has denied many of the claims made and said it would be responding personally to those who had signed the letter.
The insurer responded to COVER stating that the review process was prompted by the rate of knee arthroscopy among its customers being more than double that of NHS patients, with some surgeons' referrals being three times higher.
"We are asking orthopaedic consultants to complete a simple form to ensure that any knee arthroscopy we fund meets published evidence-based guidelines. We are not asking them for a report," it said.
"Where knee arthroscopies are in line with published evidence-based guidelines, which we expect in the majority of cases, we will authorise funding the next working day so there will be no impact on the patient.
"If a case appears not to be in line with these guidelines, we will seek an independent review from one of our clinical advisers, who are UK-based consultant knee specialists.
"The purpose of the review is to advise if the procedure is in line with guidelines, not to give a second opinion," it added.
The BOA letter had questioned where these guidelines had originated, but Bupa explained it would be using published evidence-based guidelines from sources including the National Institute of Health and Clinical Excellence (NICE), the NHS Map of Medicine, and Osteoarthritis Research Society International.
It also raised the spectre of "serious legal, ethical and General Medical Council (GMC) considerations" for consultants conducting the provider's medical review.
Again, Bupa denied this, saying it has found no legal or ethical issues in the medical review process and that having reviewed GMC standards it felt there was no basis for the claims to be made.
Dr Annabel Bentley, medical director of Bupa Health and Wellbeing, explained that although it expected some variation, the provider needed to understand the reasons for the differences in surgery rates from NHS norms.
"We want to work with doctors to ensure that we fund only clinically appropriate treatment covered by our members' policies," she said.
"We want to ensure our members are receiving treatment in line with published evidence-based guidelines and that they do not risk surgery when the evidence does not support this.
"As we have no shareholders and exist for our customers' benefit, we have a duty to pay only for treatment that meets published evidence-based guidelines.
"Every year, around 19,000 Bupa customers have a knee arthroscopy. High quality reviews of medical evidence conclude that patients do not benefit from knee arthroscopy for certain conditions, such as chronic knee pain due to osteoarthritis," she added.
