Richard Johnson gave up several rides at Towcester on Thursday after suffering a fall in the opening race.
The champion jockey was partnering the Dr Richard Newland-trained Aaron Lad in the two-and-a-half-mile novices' hurdle when his mount fell at the second flight.
Johnson walked away from the incident, but stood himself down for the remainder of the card.
Towcester clerk of the course Robert Bellamy said: "Richard is having some physiotherapy and hopes to be back riding on Friday."
Johnson has three booked rides at Newbury on Friday and is due to partner Missed Approach in the Ladbrokes Trophy on Saturday.