Free agent Johnny Knox has decided to retire from football, telling the Chicago Sun-Times he's "moving on and going forward."

It's a sad end to a once promising career. According to the Sun-Times, Knox is still walking with a limp 14 months after his spinal fusion operation, and "struggles to sit or stand" comfortably. "I was centimeters away from being paralyzed, so just sitting here and talking, I'm appreciative of that," Knox said Wednesday. "Just the hard work that I had to put in. Just to be able to stay in and do everything in my daily life that I used to do." Only 26 years old, the former fifth-round pick ends his career with 133 catches for 2,214 yards and 12 touchdowns over 45 games.

Multiple sources tell the Chicago Tribune that free agent Johnny Knox is "unlikely to play again."

Free agent Johnny Knox's agent says he plans to play in 2013.

"He's going with the mindset that he's playing in 2013," Knox's agent said. Knox is still recovering from the spinal fusion operation he underwent in December 2011, and has an "important physical assessment in late March." Knox is easy to root for, but is facing long odds of returning to the football field in 2013.

The Bears officially terminated the contract of WR Johnny Knox Tuesday.

ESPN Chicago confirms that Bears WR Johnny Knox will be an unrestricted free agent this offseason.

We read in-season speculation that Knox's salary would "toll" to 2013 because he spent 2012 on PUP, but that won't happen. After missing all of 2012 with a fractured vertebrae in his back, Knox's health status is the biggest concern for his market appeal. The 26-year-old is a quality deep threat when healthy.

Johnny Knox (back) is not expected to be activated off the PUP list by Tuesday's deadline.

Knox is slowly making process from last December's surgery to repair fractured vertebrae. He's in the final year of a his rookie contract, but a provision in the new CBA allows teams to retain the rights of their players that spend the entire year on PUP. Therefore, the Bears could bring Knox back next season for $1.26 million and give him a chance to prove his health.

Johnny Knox (PUP, back) remains unlikely to play this season.

Knox lost 30 pounds following surgery to repair fractured vertebrae last December. He's slowly working his way back into shape, but playing football is a whole other story. Knox would do well just to be ready for 2013 training camp.

Johnny Knox (PUP, back) reiterated Friday that he's unsure whether he'll be activated by the Bears this season.

We're not optimistic. "I haven't heard," Knox said. "The last thing I heard was that I was going on PUP back in training camp. That's the last thing I heard." Knox says he's upped his rehab from surgery to repair a fractured vertebrae "here and there," but doesn't appear to be making tremendous strides. "I'm out there running, moving a little bit better," said Knox. "But not too much different from the last time we talked.

Bears placed WR Johnny Knox (neck) on reserve/PUP.

He's ineligible to play in the first six regular season games, and the reporters in Chicago don't expect Knox to return at all this year. While Knox has made steady progress from spinal fusion surgery, the extensive rehab and recovery probably won't allow him to be ready until 2013.

Johnny Knox (back surgery) opened Bears camp on the active/PUP list.

Knox will assuredly stay on PUP into the regular season, disqualifying him for the first six games. We'd be a bit surprised if he played at all this year.

Bears GM Phil Emery indicated that Johnny Knox is making "steady progress" in his return from career-threatening back surgery.

"He's able to do all the lifting, he's doing quite a bit of rehab, he's doing some light running," Emery said. "He is making steady progress towards being back on the team." According to the Chicago Tribune's Vaughn McClure, Knox is making "tremendous strides" but is still expected to start the season on the PUP list.

Johnny Knox (back surgery) remains without a timetable for a return to football activities.

"Rehab is going well," said Knox. "I'm not trying to rush things and mess things up any worse, so I'm just taking it day by day." Still significantly under his playing weight, Knox concedes, "I've got a lot of work to do." Although he's been jogging, Knox has yet to begin running, six months removed from surgery.

Teammate Devin Hester believes "it's going to be a miracle" to get Johnny Knox (back surgery) "back to normal."

"I'm going to stick with him, encourage him and make sure that he doesn't give up," said Hester, who nearly broke down talking about Knox's long road back. The severe spinal cord injury leaves Knox's 2012 season very much in doubt. Even if he turns the corner by next offseason, it sounds there's no guarantee that he will recapture pre-injury form.

Bears WR Johnny Knox (back surgery) acknowledges he could miss all or part of the 2012 season.

After losing 30 pounds and regaining 10 in rehab, Knox is still a long way from participating in practices. Although he's graduated to jogging, Knox has yet to run routes. "My main focus is in the weight room. I'm not in a rush," explained Knox. "This is my spine, the core of my body I'm dealing with. It's not my knee, ankle or shoulder. I'm taking my time." Knox remains without a timetable to return.

According to ESPN Chicago's Mike Wright, Johnny Knox (back surgery) looked "very frail" on the practice field in OTAs.

He's obviously not taking part in the actual practices. Knox underwent major surgery to stabilize his vertebra on December 19 and is in danger of missing the entire season. Already a relatively skinny player, the fact that he's not staying muscle bound suggests Knox doesn't plan on playing football anytime soon.

Brandon Marshall is ticketed for split end in Chicago, leaving Johnny Knox's position up in the air.

A candidate to open the season on the PUP list following serious back surgery, Knox seems increasingly likely to play a minor role in the final year of his rookie contract. It's not clear yet if Devin Hester, Earl Bennett, or an early-round rookie will start opposite Marshall at flanker.

The player rep for Johnny Knox (back surgery) refutes a report that his client is assured of beginning 2012 on the PUP list.

"We are six months away from that decision," Knox's agent said before insisting that he hasn't had any setbacks. The Chicago Tribune reported Monday that Knox was dealing with "more structural damage than initially anticipated." The smart money remains on Knox beginning the year on the PUP list, while it's a real possibility he won't suit up at all in 2012.

"Multiple sources familiar" with Johnny Knox's (back surgery) progress tell the Chicago Tribune he'll begin 2012 on the PUP list, and there is a "strong chance" he'll miss the entire season.

The player rep for Johnny Knox (back surgery) says his client is on pace to return to full strength by July.

"His rehab has been going great," the agent said. "He's on the schedule that he planned to be back by early to mid July. He feels good." Knox won't shed his restrictive back brace until mid-March, so we're skeptical that he's going to be ready for contact by training camp.

Coach Lovie Smith suggested the Bears may finally target a big go-to receiver in free agency or early in the draft.

"A quarterback doesn't have to have that ball right in the perfect spot every time if you have a big body to throw to," Smith said, echoing Jay Cutler's recent comments. Smith realizes Johnny Knox (back surgery) is a wild card this year, so there's a need for depth regardless.