It was initially thought Turner had escaped serious injury following the incident, where she was unseated on the way to the start of the Grange 3Yr Free Servicing September grange.co.uk Handicap.
Turner was going to post aboard favourite Rose Aurora for Marcus Tregoning when the filly appeared to jink in front of the stands rail, rearing up and landing on the dual Group One-winning rider.
After being assessed in the medical room on course, Turner was believed to have suffered just bruising, but later went to hospital for precautionary X-rays, tweeting: “Ouch!! Im thinking its just badly bruised, on my way to the hospital to double check, gutted I didn’t wax my legs before I came racing!”
Her boss Michael Bell, speaking from Doncaster sales, said: “She will have an operation tomorrow, which is a real shame as the season was going so well for her. I suppose it is part and parcel of being a jockey, it’s just the timing of it — she was absolutely flying. She has had a fantastic season.
“But she’s bounced back from a worse injury in the past and she will certainly bounce back again.”
Britain’s leading female jockey has been enjoying the most successful spell of her career, riding her first two Group One winners on Dream Ahead in the July Cup and the Bell-trained Margot Did in the Nunthorpe this season.
In March 2009, Turner suffered a serious head injury while riding out on the gallops.
That fall looked set to rule her out of the saddle for 12 months following a British Horseracing Authority medical ruling, but she won her appeal and returned in July that year.
Her agent Guy Jewell said: “Unfortunately the X-ray showed a break.
“She rang me from the hospital at around 4.30pm and thought it was going to be OK, very painful but just bruised, but then she phoned later with the news.
“You have to take the highs and lows in this game, she has had a great year with two Group Ones. At least it’s not like last time and the uncertainty she had with the head injury, it’s a broken ankle and she will have a timeframe for coming back.”
Turner had been looking forward to riding Margot Did in the Prix de l’Abbaye at Longchamp on Arc day, October 2.
But Bell said: “Unless there is a miracle I’m afraid she won’t be riding Margot in Paris.”