Collie, who missed seven games in 2010 after suffering a pair of concussions, took a blow to the head from Pittsburgh linebacker Larry Foote while trying to haul in a pass from Andrew Luck. He was momentarily dazed before walking off the field under his own power and taken to the locker room for tests.
"It's preseason, so we err on the side of caution," Colts coach Chuck Pagano told reporters after the game. "He'll be evaluated further in the coming days."
"Knee issue, little bit of ankle, don't know exactly what it is," Pagano said of Redding. "Don't believe it's that serious, but he'll have an MRI on Monday."
Information from The Associated Press was used in this report.