A patient was fitted with the wrong implant during knee surgery at St Albans City Hospital.

Bosses at the hospital have changed their procedures after the patient was admitted to hospital earlier this year for surgery to replace their right knee joint.

Although the correct knee was operated on, it was later discovered that the implant used was an implant for a left knee. No corrective surgery has been undertaken, but the patient will be regularly monitored to ensure there are no problems as a result.

As a result of the error the West Hertfordshire Hospital Trust, which runs St Albans City Hospital, says there will now be a ‘stop moment’ during any operation. During this pause any implants will be checked by both the surgeon and the scrub nurse.

The incident with the wrong knee implant has been recorded by the NHS as a ‘never event’, which means an event which could have caused serious harm or death to a patient and should have been avoidable.

West Herts Hospitals NHS Trust medical director Mike van der Watt commented on the change of procedure. He said: “The ‘never event’ refers to an incident where a patient who required surgery on their right knee, had the correct knee operated on, but had a left knee prosthesis implanted.

“The prostheses for left and right are very similar and therefore, after an assessment involving senior clinicians and in consultation with the patient, it was decided that the prosthesis should remain in situ.

“We have formally apologised to the patient who receives regular check-ups in case of any problems.

“As a result of this ‘never event’ we have changed our procedures to introduce a ‘stop moment’ in theatre during which the surgeon and the scrub nurse thoroughly check the implants when they arrive to ensure they are correct.”

The NHS regularly publishes the number of ‘never events’ at trusts across the country. Provisional data published by the NHS last month highlights 294 serious incidents between April and October this year meet the definition of a ‘never event’. This is the only never event recorded by the West Herts Hospital Trust in this latest report.

The Trust also includes Watford General and Hemel Hempstead hospitals.