A man who was given the wrong knee implant during surgery said he was left speechless when the blunder was revealed.
Andrew Osbourne, 65, had a replacement operation at Gorleston's James Paget University Hospital in September.
But the implant for the right knee contained components for the left, with the error classed as a 'never event' - one so serious it should never happen.
MORE: Patient given wrong knee implant at hospital
Mr Osbourne, from Halesworth, said his knee developed osteoarthritis after his leg was badly broken in 1976.
The replacement operation was originally planned for spring this year but Mr Osbourne had to reschedule the surgery for a date in September.
He claimed that in the interim the hospital lost information on his medical background, which meant on the morning of the procedure the surgical team was "unprepared".
A spokesperson for the hospital declined to comment on the claim.
During the operation, surgeons implanted a replacement containing a left tibial component into Mr Osbourne's right knee.
"Somehow the wrong bit came out of the box," he said.
At a meeting in the hospital on September 30 the patient was informed of the mistake.
He was told the hospital was sorry and that it had not happened before.
A member of the surgical team showed Mr Osbourne two sample tibial plates, left and right, and told him he had the wrong plate in his leg.
"I was completely shocked, I was almost speechless, which is most unusual for me," Mr Osbourne said.
"I said 'how could anybody make a mistake like this'."
James Paget University Hospital's director of nursing Julia Hunt said: "An initial review of the case has confirmed the patient has come to no harm, in accordance with national guidance/criteria and definition of no harm, and a full root cause analysis investigation has been undertaken.
"The patient has been kept fully informed and no extra surgery is required, but they will be monitored on an ongoing basis.
"As with any serious incident or never event, we carry out a full investigation to find out how and why this occurred, to identify what can be learnt from the incident and whether any procedural changes are required. In the meantime, immediate actions have been taken including a review of our five steps to safer surgery process."
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