San Diego Chargers running back LaDainian Tomlinson was diagnosed Tuesday with a second degree knee sprain of the medial collateral ligament that will require at least six more weeks to heal, according to his agent, Tom Condon.

Condon told ESPN's Chris Mortensen that Tomlinson was examined by Los Angeles orthopedic specialist Dr. Neal Elattrache, who said the injury was positioned near an attachment that also "caused disruption of the hamstring fibers."

"The doctor said this is the type of injury that would seriously hamper LaDainian's ability to cut or push off the leg," Condon said. "His quadriceps muscle had already atrophied one inch. He absolutely can't play in the Pro Bowl and there shouldn't be any question as to why he couldn't go when [the Chargers] played New England."

Ravens running back Willis McGahee earned his first Pro Bowl appearance when Tomlinson pulled out.

Tomlinson carried the ball twice in the AFC Championship Game against the New England Patriots. After San Diego's 21-12 loss, NFL Network commentator Deion Sanders questioned Tomlinson's grit.

"You're a big-time player. And big-time players must play big-time games," he said.

Tomlinson fired back.

"You tell me what running back has played with a sprained MCL and been effective," he said. "You might go out there and try to limp around and play, but it's not going to happen. I don't know how information gets passed on, but until you talk to the source of the problem, what's going on with me, I think it's ridiculous when people make comments like that."

Information from The Associated Press was used in this report.