Organisations representing orthopaedic surgeons have written to the health secretary Andrew Lansley admonishing him for statements he made about the outcomes of knee surgery, which they say were misinformed and could have deterred patients from having operations and alarmed others about their prognosis.

The letter is a response to an interview with Mr Lansley in the Sunday Times on 29 January, in which he said, “An interesting case in point is knee surgery; the data has now come back demonstrating half of knee surgery doesn’t substantially change the outcome for patients: their mobility isn’t improved that much, nor their pain.”

Joe Dias, president of the British Orthopaedic Association, and Tim Wilton, president of the British Association for Surgery to …