Cleveland, though, hopes the heralded rookie will be able to rebound from left knee surgery in time for the season opener.
"We anticipate that Trent will make a speedy recovery, and we are hopeful that he will be ready for our Week 1 game against Philadelphia," coach Pat Shurmur said Thursday in a statement issued by the team.
Richardson, the quick and powerful running back drafted No. 3 overall, underwent what the Browns termed "routine arthroscopic" surgery by Dr. James Andrews in Pensacola, Fla., as expected.
Andrews did a similar procedure on Richardson on Feb. 3, to repair damaged meniscus cartilage.
Richardson sat out practice for the first time Tuesday with soreness in the knee. The Browns were hopeful that Richardson, who helped lead Alabama to the national championship in January, would make a quick recovery in time to play Friday night in Detroit against the Lions in the preseason opener.
Montario Hardesty will start in place of Richardson against the Lions. It will be an opportunity for Hardesty to see how far he has come back from knee surgery two years ago.
"It's a chance for the whole team to go out and show what they can do," said Hardesty, a second-round choice in 2010 who was injured in preseason that year and missed his entire rookie year.
"I'm excited, but I would be anyway," Hardesty said. "It will just be good to go out
Shurmur said Chris Ogbannaya, a midseason pickup from Houston last year, and former Green Bay running back Brandon Jackson will also see time. Jackson hurt a toe during the Browns' preseason game against Detroit last August and though he did not need surgery, missed the entire season.
The Browns came to training camp this year confident that rookie quarterback Brandon Weeden, Richardson and other draft choices could help them improve upon successive 4-12 finishes. Instead, they have been hit hard by injuries.
Defensive lineman Phil Taylor, their first pick a year ago, is out until midseason after pectoral muscle surgery. Veteran linebacker Chris Gocong is done for the year with a torn right Achilles tendon.
In addition, linebacker Scott Fujita is facing a three-game suspension for his role in the Saints' bounty scandal, and cornerback Joe Haden may be suspended four games for reportedly failing a test for banned substances.
Fujita's appeal on his suspension will be heard Friday. Haden, the Browns and the NFL have not officially addressed rumors of the defensive back's situation.