Mingo was hospitalized for two days at The Cleveland Clinic after he sustained the unusual injury some time in the first half of Thursday night's win over the Detroit Lions. The No. 6 overall pick in this year's draft said he coughed up blood and experienced shortness of breath on the sideline before he told coaches and the team's trainers that he was hurt.
Banner said Mingo will have more tests and the team does not yet know how long he will be out.
"We really don't,'' Banner said after giving reporters a tour of the team's renovated headquarters. "(The timetable is) still fairly open-ended. Hopefully we'll get more information soon and have a better idea.''
Mingo was released from the hospital on Saturday morning. After watching that afternoon's practice, the 22-year-old said he did not injure his ribs and attempted to downplay an injury that could have potentially been fatal if untreated.
Mingo believes he got hurt while covering the opening kickoff, but he wasn't certain because he didn't take a big hit. He'll miss this week's preseason game at Indianapolis, and it's still to be determined how much more time the 6-foot-4, 240-pounder will be sidelined.
Banner made it clear the Browns will be cautious with Mingo - or any injured player.
"I think you've got to make sure he's fully healthy before you put him back out there and then he should be at no greater risk than anybody else, at least as I understand it,'' Banner said. "But you've got to make sure. With any injury, if you put him out when they're only 75 percent healed, you're at greater risk of something happening. So we've got to make sure he's fully good to go.''
Banner said the nature of Mingo's injury caught the Browns a bit off guard.
"Anytime a player gets hurt, especially one where it's sort of ambiguous - some of these injuries are, `I did this, OK, that's two weeks. You did this, that's eight weeks.' Obviously the range of this being from minor to quite serious is larger than most injuries. But you know we've got top quality medical people and they were fairly quickly able to assure us and get him in a place where we were able to determine that he was in good shape.
"Mostly it was initial, 'What is that? How'd that happen?' But I think as soon as you understood, we were at a point where the medical people had done enough to make us feel confident that it wasn't going to be a big deal.''
As for Lewis, the Browns still don't know if he'll be able to help them this season. The third-year back fractured his fibula while being tackled in the third quarter of Cleveland's 24-6 win.
The Browns have two options with Lewis: place him on season-ending injured reserve, or put him IR and designate him to return after Week 8 of the regular season, if they think he can come back.
"We won't have any idea until after the surgery,'' Banner said. "Even then, we may or may not have any more clarity than we do right now. It just may be a matter of seeing how it heals.''
Lewis has been a great addition for the Browns, who acquired him in an April trade from Philadelphia. He complements starter Trent Richardson well as third-down back, who can also run between the tackles. Lewis played in 24 games the past two seasons for the Eagles.
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