Ruby Walsh hopes to return to the saddle in time for the Punchestown Festival, which begins on April 24.
After being on the sidelines for four months with a broken leg, the rider was back in action the week before the Cheltenham Festival, having two rides, and recorded a double on the opening afternoon of the big meeting, which included Footpad in the Arkle Trophy.
However, a fall at the second-last from Al Boum Photo in the RSA Insurance Novices' Chase on the second day aggravated the old injury.
Walsh told Racinguk.com: "I saw my doctor Diarmuid Moloney and the diagnosis is that it's a very similar fracture on the inside of the original one, which has effectively opened up.
"It's good news in that the cast has come off and I am in an air-cushioned boot right now. I don't know exactly how long it will take to heal but it means I am hopeful of getting back for Punchestown - Aintree is not going to happen for me though.
"The prognosis could have been a lot worse and I just have to treat this as just another setback. I am determined to get back in the saddle for Punchestown and hopefully finish the season on a high."