Freddie Tylicki has been left paralysed from the waist down following his horror fall at Kempton Racecourse earlier this week.
The 30-year-old had to undergo emergency surgery after being thrown from his horse along with three others, including Jim Crowley who was also hospitalised.
Four days on from the mass pile-up, it has now been revealed that Tylicki - who was riding Nellie Deanis in the 3.20pm race - is now restricted to movement in his upper body as a result of the incident.
Lisa Hancock, the chief executive of the Injured Jockeys Fund, said: "After his fall at Kempton Park Racecourse earlier this week, Freddy Tylicki was transferred to St George's Hospital in London, where he has since undergone surgery to his spine.
"His surgical team have confirmed that Freddy has a T7 paralysis, which means he has movement in the upper half of his body but not his lower."
Crowley suffered a broken nose in Monday's accident, which resulted in the event being abandoned for the day.