An NHS Trust that struck off a surgeon for a prosthesis error recorded another four separate incidents after he was dismissed, according to new data. Emyr Chowdhury was removed from the medical register in February 2021 due to a 2016 incident at Peterborough City Hospital when he replaced a left knee joint with a right knee prosthesis and hid the error from the patient.
The hospital’s overseeing body, North West Anglia NHS Foundation Trust, were then alerted to four more wrong implant or prosthesis cases between September 2021 and the end of last year.
The reports, which were shared with Medical Negligence Assist, also noted an August 2020 incident which means the Trust were notified of five wrong implant or prosthesis incidents in the space of just over four years.
Never Events recorded by Trust
Two cases noted by North West Anglia NHS Foundation Trust in the past five years have been deemed a ‘Never Event’, which NHS England defines as a “serious, largely preventable patient safety incident”.
The first, in August 2020, involved a mistake with the locking mechanism for a trunnion. Damage to a trunnion can cause trunnionosis or a trunnion fracture, which can lead to a failed hip replacement.
A second Never Event was logged in September 2024. The mistake involved a toric intraocular lens, an implant used to correct astigmatism in cataract surgery.
Another intraocular lens was the focus of a report from October 2022, with the error recorded as a ‘Serious Incident’ by the Trust.
Further cases were brought to the Trust’s attention in September 2021 and March 2022. However, the incidents involving a meniscus implant and the insertion of a medial tibial plate were not considered serious upon review.
The Trust confirmed that two of the five cases led to the patient suffering harm.

“Communication”, “human error” and “incorrect biometry readings” were all named as causes of the incident, with the Trust also stating that the implants were not available in the correct size or form or had been mismatched.
Trust sued for wrong implant or prosthesis negligence
NHS Resolution, the litigation arm of the national health service, confirmed that North West Anglia NHS Foundation Trust has paid compensation for at least one medical negligence claim due to an implant or prosthesis error.
It did not confirm specific numbers but said that “fewer than five” claims were resolved in 2020/21.
NHS Resolution did not state whether any claims against the Trust remain in progress.
In total, 51 English Trusts or independent health services had claims settled on their behalf by NHS Resolution between April 2019 and March 2024.
45 of them paid damages, meaning a total compensation cost to the NHS of £2,598,920.
Medical Negligence Assist found that numerous NHS Trusts had recorded incidents involving a wrong implant or prosthesis.

The issues highlighted involved further examples of the wrong knee implant being used, as well as a near miss involving an incorrectly sized shoulder replacement and a patient suffering harm because their nickel allergy had not been noted before a prosthesis was inserted.
Medical Negligence Assist is a 24/7 service which offers guidance on medical negligence compensation claims.
People affected by a surgical error can contact them online or via 0800 652 3087 for free information and support.
FACT FILE
The data shared in this release was obtained through Freedom of Information Act requests sent to NHS Trusts and NHS Resolution. A copy of any FOI response collected is available upon request.
A link to https://www.medicalnegligenceassist.co.uk/
Infographic credit: www.medicalnegligenceassist.co.uk
You can read the full, detailed research into wrong implant/prosthesis cases via a research and statistics page