IndyCar driver Stefan Wilson underwent back surgery to repair the fractured vertebrae he sustained in an Indianapolis 500 practice crash at Indianapolis Motor Speedway on Monday.

Wilson underwent the surgery Wednesday night to repair the 12th thoracic vertebrae that was injured during the crash. Doctors at IU Health Methodist Hospital performed a posterior fusion and internal fixation of the T10-T12 vertebrae, according to Dreyer Reinbold Racing, Wilson's team.

Speaking from his hospital bed on Thursday, Wilson was optimistic about his recovery.

"I feel a lot better today," Wilson said in a video posted from his hospital bed. "The recovery journey starts now and the race recovery for the 2024 Indy 500 is starting now. ...

"I'm so thankful -- thank you to everyone that's reached out from messages. It means a lot. It's helped me keep my spirits high. Obviously I'm so disappointed that I couldn't be racing this weekend but the focus is on the future."

Wilson, who qualified 25th, will be replaced in Sunday's Indy 500 by Graham Rahal, who had failed to quality. Rahal usually drives for Rahal Letterman Lanigan.

During Monday's practice session, Wilson's car was struck from behind by Katherine Legge's car and was sent into the barrier. After Wilson was removed from the car, he was placed on a stretcher and was wearing a neck brace before being loaded into the ambulance.

"I feel for Stefan. I've said that numerous times here. I feel for him tremendously because I do know how much this means to him and how much work he puts in year-in and year-out to be here," Rahal told reporters. "This is the truth, in some other situations, I don't think that it would have excited me as much, but being that it was Stef and being that it was a Wilson, and in the situation that it was in, I just felt like it was my calling to jump in and help."

Wilson has raced in four previous Indy 500s with a high finish of 15th in 2018.

His brother, Justin, was killed in 2015 at Pocono Raceway when debris from a crash struck him in the helmet.