Four jockeys were injured in falls at the Aintree Festival near Liverpool, England on April 4, with Mikey Fogarty and Paul Carberry both hospitalized.
All four fell during the Topham Chase, which is run over the same Aintree Racecourse fences used for the showcase Grand National Steeplechase on Saturday, April 5.
Carberry fell off Kauto Stone and underwent precautionary x-rays on his pelvis before being discharged, according to the Professional Jockeys' Association. Carberry, who won the 1999 Grand National on board Bobbyjo, is booked to ride 10-1 shot Monbeg Dude on Saturday.
Fogarty was unseated while riding Bishopsfurze, and the PJA said he had fractured two vertebrae. He was due to ride 66-1 shot Vesper Bell in the National.
Andrew Tinkler and Noel Fehily also face fitness tests ahead of Saturday's race. The BBC says Tinkler hurt a wrist, and Fehily sustained an elbow injury.
Ma Filleule, a 9-1 shot ridden by Barry Geraghty, won the Topham Chase.
In the feature race, the Melling Chase, Paul Townend produced a late challenge on board Boston Bob to claim victory. The 9-year-old hurdler, a 5-1 shot, showed a quick turn of foot between the last two fences, bringing him from seventh place to a narrow lead.
Boston Bob beat Rolling Aces by 3 1/4 lengths and Ballynagour finished third.
''I didn't want to put him on his head early on, so I let him work his way into it and find his rhythm,'' said Townend, deputizing for injured jockey Ruby Walsh. ''He seems to have sorted himself out now, and he deserved that.''