Colleagues and former patients are angry about the suspension of Ian Mackie by South Glamorgan Health Authority and have set up a support committee. Posters and banners have been put up alongside roads.
Mr Mackie, 42, from Llandaff, Cardiff, a consultant at the Prince of Wales Hospital, near Cardiff, was suspended last month. The hospital carries out joint replacements on patients from all over Wales.
The action followed a dispute over a tender for replacement joints. Mr Mackie, an experienced surgeon who is popular with patients, was unhappy about the contract going to a company that supplied a different type from that previously used.
He is alleged to have cancelled some knee operations and to have told patients that this was because the right joints were not available. He is said to have claimed that he had no experience of fitting the new type.
This and some other matters are being investigated by the health authority and the General Medical Council. The Audit Commission is watching the progress of the inquiries and may launch its own.
John Jenkins, spokesman for the health authority, said yesterday: 'He has been suspended pending investigation into allegations of gross and professional misconduct. The investigation may result in disciplinary hearings.'
The allegations of gross misconduct involve cancelling operations, not telling patients the true reason, allowing someone to help him in his private practice without NHS approval and working privately while on special sick leave.
The claims of professional misconduct, which are being investigated by the General Medical Council, also involve cancelling operations and not telling patients the correct reason plus allegations about the supervision of a contract for hip and knee replacement operations.
The health authority should complete its inquiry within a month. The GMC investigation could take up to six months. Either could result in Mr Mackie's dismissal.