Rodney Harrison knows a little something about knee injuries.

In September 2005, the former Patriots safety suffered a devastating knee injury, tearing the anterior cruciate ligament, medial collateral ligament and posterior cruciate ligament in his left knee against the Steelers, ending his season. He didn’t make it back until roughly 11 months later, and even then, he admits he wasn’t the same player he was before the injury.

That’s why, in the wake of the injury to Wes Welker — NFL.com reported that an MRI done Monday on Welker’s injured left knee showed torn anterior cruciate and medial collateral ligaments in his left knee — Harrison was understandably pessimistic about Welker’s future.
 
“It’s never going to be the same,” Harrison told reporters who asked about Welker Tuesday on a national conference call.

Harrison actually suffered a few season-ending injuries with the Patriots. The knee injury in 2005 prematurely ended his season. In 2006, he suffered a right shoulder injury in November against the Colts and fought his way back, only to go down with a right knee injury in the regular-season finale against the Titans.

And in 2008, his season — and his career — came to an early end when he tore his right quadriceps femoris muscle in an October win over the Broncos.

He said that when it comes to a knee injury of this magnitude, timing is everything.

“This is a devastating injury for a guy like him, because the worst thing as a player is to hurt yourself at the end of the season,” Harrison said. “You never want to hurt yourself. But, if you hurt yourself, at least let it be in the first half of the season. Now, you have roughly three or four months where you can continue to heal and all of a sudden, the very next year, you have an opportunity to heal and get ready to play.

”Now, you get injured in January, it’s going to take 11 months. It took me 11 months to have surgery, rehab and get on the practice field. It really took me to the seventh week to start feeling good. I had a little more devastating injury than Wes Welker because I tore my PCL as well as ACL and MCL. But coming back with the type of injury he has and depending on his ability to cut and move and shift, it’s going to be a tough injury for him to come back.”

According to Harrison, who played alongside Welker for the 2007 and portions of the 2008 campaign, the Texas Tech product does have a lot going for him — mainly, a tireless work ethic, which he’ll need throughout the rehabilitation process.

”The one thing about Welker is he’s in phenomenal shape, he’s a hard-working guy, a guy that really focuses on keeping himself in tremendous shape,” Harrison said. “And that’s one of the things that will help you recover from an injury like this.

”Going on the fact that you’re in tremendous shape, the work ethic and being mentally tough because once you tear up your knee, it’s never going to be the same no matter if you come back, if you’re wearing a brace, especially a slot receiver like Welker. I’m concerned for him going forward into the next season because realistically I don’t know if he’s going to be back until November.”

In his place, the Patriots likely will make do with rookie Julian Edelman in the slot. While Harrison said Edelman “looked great last week,” he has his doubts about how far his former team can get without Welker. (He said Tuesday he’s picking the Eagles to win the Super Bowl.)

“I mean, close to 60 percent of his passes have gone [for] first downs, as well as his ability to score in the red area. He’s very dangerous. He’s a tremendous leader, a very dependable guy,” Harrison said of Welker.

“I think just talking to people down there, they have a lot of confidence in Julian Edelman. He was very inconsistent during the early part of the season, but he looked great last week.”

Harrison also sees Patriots coach Bill Belichick and the rest of the offense using the injury as motivation, and believes New England “will respond” in Sunday's postseason opener against the Ravens.

“He’s going to use this to best of his ability to motivate these guys,” Harrison said. “Basically, what he’s going to tell those guys is, ‘Offensively, they feel like we can’t put up points, can’t score. They feel like Wes Welker was the best player outside of Tom Brady on this team. They’re not giving us a chance.’ So the players in that locker room will use that as motivation.”