Medical personnel carted Knox off the field on a stretcher in the first quarter of Sunday's loss to Seattle after the receiver -- scrambling to recover his own fumble -- absorbed a devastating hit from Seahawks defensive end Anthony Hargrove.
Knox suffered a fractured vertebra, the team said, and surgery was performed to stabilize it. Knox's injury is not considered career-threatening, but the team reported on its website that it's not clear if he'll be ready in time for training camp.
"If you look at it, it was a brutal hit that he took," said Bears coach Lovie Smith. "As we talk right now this morning, he has been in surgery to stabilize his vertebra. He's out of course the rest of this year. But just looking to the future, it looks bright for him of course to play and get back there. So we're encouraged by that."
Knox caught a 17-yard pass from Caleb Hanie on a slant route in the first quarter, and as the receiver attempted to make a move to get free, Seahawks safety Kam Chancellor poked the ball loose. Knox dove immediately to pick up the loose ball, and was hit by Hargrove in the process, bending the receiver backward awkwardly.
Smith declined to call the hit illegal.
"No, I can't say that (it was dirty)," Smith said. "(The) guy was playing hard, an unfortunate play. It's a violent sport, and sometimes ... you don't see hits like that very often. But I can't say that it was dirty or anything like that."
The Bears also placed safety Chris Conte on IR because of a foot injury he suffered in the game and promoted running Armando Allen, defensive end Thaddeus Gibson and receiver Max Komar from the practice squad, signing them through the 2013 season Monday.
Michael C. Wright covers the Bears for ESPNChicago.com and ESPN 1000. Information from The Associated Press was used in this report.