The NFL is predicated on a game of violence.
For 60 minutes, the world's greatest athletes pound on each other for our viewing entertainment.
But with that violence comes the reality of injury, and in the NFL, it comes at a rate that far exceeds most other professional sports.
The 2011 season was no different, as a number of NFL stars were lost for significant periods of times with catastrophic injuries. That list includes the likes of Minnesota Vikings running back Adrian Peterson, who got his knee twisted up late in 2011 and tore a number of ligaments.
Leading into next season, there are still major concerns about players rehabbing those injuries, including Peterson.
In the following slides, we'll breakdown the players who still have concerns ahead of the 2012 season.
Despite tearing up his knee in a visually graphic injury during Week 16 last season, Peterson appears to have a Week 1 return in his sights. Considering the severity and timing of the injury, Peterson is lucky that spending the first six weeks of the 2012 season on the PUP list isn't the reality he's facing.
Such is life for the physical freak that is Peterson.
During Vikings' minicamp this week, Peterson began running full speed and making cuts, according to the St. Paul Pioneer Press. Peterson thinks he'll be able to participate in training camp.
"My goal is to be able to go out and participate somewhat during training camp," Peterson said. "How much, I'm sure, the staff will evaluate things and let me know. I'm just going to go with the flow."
Peterson's offseason recovery has obviously eased many of the concerns ahead of 2012, but keep in mind he has a long ways to go in getting back to 100 percent. Hopefully, the Vikings medical staff ensures that Peterson doesn't rush back too soon and risk further injury to a knee that was shredded up about seven months ago.
There are few NFL backs as physically talented as McFadden, but a string of injuries has kept the 24-year-old from ever playing in more than 13 games in any of his four NFL seasons.
In 2011, McFadden played in just seven after suffering a Lisfranc sprain in October of last year. Once considered minor, the injury bothered McFadden enough that he never played another down after Week 7 last season.
Steve Corkan of the Contra Coast Times reported during organized team activities (OTAs) that McFadden looked "100.62 ready" to play in the 2012 season. Obviously, that remains a good sign for McFadden to start next season.
However, McFadden needs to start shedding the injury label that has dogged him throughout his NFL career. If the Raiders are to make anything of their 2012 season, it will likely be with a healthy McFadden leading the way.
A torn ACL in Week 2 against the Detroit Lions ended Charles' 2011 season before it ever really got started. By the time training camp rolls around in July, Charles will have about 10 months of recovery time between injury and the start of camp.
According to the Kansas City Star, Charles has no worries about being medically cleared for camp, and he could play in a game right now if the Chiefs needed him too.
Kansas City will obviously keep a cautious approach with Charles, and they should—he's one of the game's most electric backs when healthy.
But therein lies the concern for Charles: After a reconstruction on his knee, will he be the same explosive cut-and-go back he was pre-injury? Will the speed come completely back? Is there going to be any hesitation?
ACL tears are no longer the career-altering injuries they once were. But I'm not sure expecting Charles to be the same player right away in 2012 is clear thinking.
Considering all the hoopla around his release from the Colts and eventual signing with the Denver Broncos, doesn't it seem like the injury to Manning's neck—you know, the reason he missed the 2011 season and was then released by Indianapolis—has gotten somewhat lost in the shuffle?
Manning has underwent at least four surgeries on the neck in the span of 30 months, and there's no telling how it will repsond once the four-time NFL MVP returns to the actual playing field. Throwing the ball around in a helmet and shorts doesn't really give much indication in how the neck is actually holding up.
According to the USA Today, Manning knows that he's still in the rehab phase with his neck.
"I still have a lot of work to do,'' Manning said following a checkup with team doctors. "I continue to rehab. I have work to do and progress that I still need to make.''
There's little doubt that Manning won't be ready to start 2012, but one wrong hit on the 36-year-old quarterback could be all she wrote on his NFL career. Let's make sure we keep that in perspective.
A Week 1 return has always been the recovery timetable for Britt, who blew out his knee in Week 3 of 2011 and then had reconstructive surgery in early October.
Despite two other "clean up" surgeries on the knee since, it still appears Britt will be available come the start of the 2012 season.
According to the Nashville Tennessean, Britt began cutting drills last week—which still puts him ahead of schedule.
“They surprised the heck out of me today,” Britt said last week. "And I did it without the brace, too. … On my first one I was a little hesitant, but it felt good and after that, it was all out.”
However, the injuries have started to pile up for the 23-year-old receiver. Britt missed most of the 2011 training camp with a hamstring injury, and he hasn't played in a full season since his rookie year in 2009.