Lions begin the PUP brigade

As NFC North training camps open this week, there will inevitably be a group of players who aren't physically ready to begin practicing. They'll be placed on the physically unable to perform (PUP) list, or similar, and work with athletic trainers apart from the rest of the team until they're ready to practice.

The Detroit Lions started the process Tuesday, a day after their rookies reported to camp, by placing cornerback Chris Greenwood and defensive end Ronnell Lewis on the PUP and receiver Ryan Broyles on the active/non-football injury list. Greenwood is recovering from abdomen surgery and Broyles apparently isn't quite ready to let loose as he recovers from a torn ACL. Lewis' ailment is unknown at the moment. All three players are 2012 draft choices.

I would expect a number of players from around the division to fall into similar categories. The Chicago Bears almost certainly won't have receiver Johnny Knox, whose career is in doubt because of a serious back injury. Green Bay Packers tight end Andrew Quarless (knee) and offensive lineman Derek Sherrod (leg) might need more recovery time, and it's almost a certainty that Minnesota Vikings tailback Adrian Peterson (knee) will find his way to the PUP later this week.

More to come, for sure.