Cape Town - Britain's Chris Froome suffered a fracture to his neck in Wednesday's crash, scans have shown.
According to the BBC website, the four-time Tour de France champion faces six weeks in hospital and is not expected to compete again this year.
Froome, 34, lost consciousness after the crash and also sustained a fractured right femur, a broken hip, a fractured elbow and fractured ribs.
He is likely to spend "at least six months" away from cycling, says the surgeon who operated on him.
Froome had a six-hour operation, which has been described as a "success" although chief surgeon Remi Philippot said it was "difficult to be sure" on an exact length of time for his recovery.
Doctors have said they are "very happy" with Froome's progress, and Team Ineos confirmed he will remain in hospital for the next few days.
The crash happened during a practice ride before stage four of the Criterium du Dauphine in Roanne, France.
In footage captured by ITV4 minutes before the incident, a team-mate tells Froome "you don't have to take risks, Chris" as he takes both hands off the handlebars to put on a jacket.
But moments later, Froome took his hand off his handlebars again to blow his nose and was travelling at 54km/h when a gust of wind caught his front wheel, causing him to hit a wall.
He was airlifted to St Etienne Hospital.
"First things first, the surgery was a success," said Team Ineos doctor Richard Usher.
"The operation, which lasted for six hours, went very well.
"Chris woke up and was reviewed by the intensive care consultants and the orthopaedic specialist who operated on him and they're both very happy with his progress to date.
"Chris will remain in hospital for the next few days for observation, but he is already actively engaging in discussing his rehabilitation options, which is very encouraging."
Philippot also told BBC Sport: "Chris was totally awake - he wanted to know when he can cycle again.
"Professional sports people are very good mentally and want to win but maybe I think I have to slow him down because he's very quick and wants to go fast but bone healing needs at least two months so we have to be patient."