INDIANAPOLIS -- You probably went to the internet to Google “medial sprain” after hearing Colts coach Chuck Pagano reference the term when talking about Pro Bowl cornerback Vontae Davis ’ ankle injury Monday.

You also probably weren’t the only one who had to look it up, either.

The injury is severe enough that ESPN NFL Insider Adam Schefter reported Monday night that Davis has ligament damage in his ankle that will cause him to miss at least the first month of the season. The Colts play Detroit, Denver, San Diego and Jacksonville in their first four games.

The Colts signed veteran Antonio Cromartie to help in the secondary Monday.

I reached out to ESPN injury expert Stephania Bell to try to explain how a medial ankle sprain is different from a typical ankle sprain. The biggest difference, she said, is that it’s the inside of Davis’ ankle that’s injured.

“This is not your typical ankle sprain. Medial sprains are less common, for sure,” Bell said. “If you’re standing and you rolled your ankle so that the inside of the sole of your foot is pointing out and the inside of your ankle is rolling like it is going to go in and touch the ground, that's how you stretch the medial side of the ankle. It’s an injury to the ligaments on the inner side of that ankle. I can’t put a definite timetable on it because I don’t how much damage was done.”

Davis, who has missed only one game over the past three seasons with the Colts, was wearing a cast when he left the locker room Monday.

“Sometimes guys will get a cast to immobilize the ankle,” Bell said. “They want to keep it from moving. They put it there because they just want to get whatever is injured to scar down and they want to minimize the chance they’re going to move it so that you don’t aggravate any damage you have.”