British surgeons are preparing to carry out the UK's first face and hand transplant.
A team at the Royal Free Hospital in north London is assessing patients for the procedure, which has only been performed once before in France.
Professor Peter Butler, director of surgery and trauma at the Royal Free, has been researching face, and face and hand, transplants for much of his career.
In 2006, he received the go-ahead for the UK's first full face transplant and is now waiting for a suitable donor match.
Several patients are also being assessed for a combined hand and face transplant, and are undergoing rigorous psychological testing.
It comes as surgical experts at the National Institute for Health and Clinical Excellence (Nice) said there needs to be "more evidence" on the possible risks and benefits of hand transplant surgery.
In new guidance, it said health professionals should explain the uncertainties and possible risks to all patients considering the operation before they give their consent.
Nice had been asked by British surgeons to look at issues surrounding the operation but the organisation has no power to prevent it from happening.
Prof Butler's team is working with surgeons in Birmingham, Austria and Pittsburgh in the US to share information on proceeding with the transplant.
The surgeon, who is head of the UK Facial Transplantation Research Team, said face and hand transplants had long been part of his team's research programme.
