A woman struggling to walk after an operation by a neurosurgeon had unacceptable treatment, doctors say.
Since 2014, the care of Hussien El-Maghraby has been scrutinised, with an inquiry ruling three years later he should no longer perform complex procedures without further training.
Among the cases was his spinal surgery on Judith Mills, which surgeons have now told the BBC was flawed work.
Mr El-Maghraby has been contacted for comment.
When he operated on Ms Mills in 2014, he was a consultant neurosurgeon at University Hospital Coventry. Neurosurgeons' discipline can involve spinal surgery as it focuses on disorders of the central nervous system.
The procedure on the NHS patient, who had severe back problems including curvature of the spine, was carried out at Woodland Hospital, a private site in Kettering, Northamptonshire.
Days later, amid concern over numbness and the placing of spinal screws, Ms Mills was transferred as an emergency to the Coventry hospital where she was operated on again by another surgeon.
She then spent seven months at the site, unable to get out of bed.
More than four years on, Ms Mills, from Market Harborough, Leicestershire, says she is incontinent and virtually unable to walk.
"I am not good," she said. "I can't drive. I can't do anything I want."
She said prior to surgery, she had no bladder problems and was more mobile.
Ms Mills requested her scans and records of Mr El-Maghraby's operation; material which the BBC has shown to specialists.
In response, they were highly critical of his work.
Among the group is Nick Birch, former secretary of the British Association of Spine Surgeons.
He said Mr El-Maghraby had put all but two of seven screws he attached to Ms Mills' spine in the wrong place or with incorrect application.
"[These screws] breached the spinal canal causing neurological impairment," Mr Birch concluded.
He branded it an "unacceptable rate of failure" and called for an investigation by the General Medical Council.
In a letter seen by the BBC, the surgeon who operated on Ms Mills after her emergency transfer also referred to poorly-placed screws.
However, a 2014 review of Ms Mills' operation concluded "the level of care given by Mr El-Maghraby was appropriate to that expected from a consultant neurosurgeon".
It was commissioned by University Hospital Coventry after concerns over Mr El-Maghraby were raised by his former colleague there, neurosurgeon Munchi Choksey.
Mr Choksey has joined Mr Birch in criticising Ms Mills' treatment and expressing frustration over the review's finding.
The review was led by a consultant neurosurgeon from another NHS trust, Neil Kitchen, who has been contacted for comment.
Mr Choksey told the BBC he too was concerned over screw placement, saying of Ms Mills' procedure: "The manner in which the surgery was carried out was appalling."
At the time, Mr El-Maghraby claimed Mr Choksey's complaints were malicious and he made a formal complaint of bullying, although the matter went no further, with no action brought against his colleague.
Another review of Mr El-Maghraby's surgery was later commissioned by the hospital, which was carried out by the Royal College of Surgeons (RCS) in 2017.
The hospital had pointed to four so-called "clinical adverse events" involving both brain and spine surgeries and cited concerns over quality and safety.
These included surgery on Stephen Bridgman, from Redditch, Worcestershire, who died after Mr El-Maghraby operated on his benign brain tumour in Coventry in 2016.
The RCS concluded that without further training, Mr El-Maghraby should no longer carry out two kinds of procedures - complex spinal operations and brain surgery while patients were awake.
University Hospitals Coventry & Warwickshire NHS Trust told the BBC it would not comment on whether he had since received the training, but said he was not currently working in the area of complex spinal surgery.
A spokesperson for Woodland Hospital, where Mr El-Maghraby was the subject of an internal investigation, said: "[We] agreed to the voluntary suspension of Mr El Maghraby during the investigation and his subsequent withdrawal of practising privileges after the investigation was concluded."
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