INDIANAPOLIS – As expected, Shaquille Leonard’s season is over.

The Indianapolis Colts’ All-Pro linebacker underwent back surgery Tuesday that will sideline him for the remainder of the season. NFL Network’s Ian Rapoport was first to report the development.

It marks the second back surgery in five months for Leonard. He had the first on June 9, and it addressed two disks in his neck that were impacting nerves and causing pain and a lack of strength in his left leg and calf. The initial rehab forced him to miss the first three games of the season.

After missing an additional three games because of a concussion and broken nose suffered in the Colts’ week 4 loss to Tennessee, Leonard returned and was on a pitch count against Washington and New England.

He practiced last Wednesday but experienced a setback that forced him to miss the rest of the week. He told the media during his normal Thursday access “the nerve still isn’t firing in my calf.’’

He was placed on the injured reserve list Saturday, and ESPN reported Leonard was seeking the advice of noted back specialist Dr. Robert Watkins in Los Angeles on Monday.

Leonard appeared in just three games this season and was on the field for a total of 74 plays. He missed the first three games because of the original back surgery.

Last week, he insisted he was making progress, but admitted there still was a problem.

“Each week I feel better,’’ Leonard said. “Starting from first day of practice, being stiff, really can’t move. And then in the game was stiff. And in the past two games, I see myself moving around better.

“It’s still not there. The nerve still isn’t firing.’’

Leonard remained defiant.

“I’m not going to tuck my tail,’’ he said. “I have faced so much adversity in my life, and I know how it feels. I know how to fight through it.’’

The entire season has tested his resolve. He’s been limited to 11 tackles, one interception and one pass defended.

“It’s hard being in and out,’’ Leonard said. “For one, not being a starter; two, missing games, splitting reps, pitch count. There’s a lot of frustration.

“It’s a lot of things that I can’t control.’’

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You can follow Mike Chappell on Twitter at @mchappell51.