For all the talk of the impact of concussion injuries in the NFL, it's knee injuries that the players fear the most according to a recent survey.
New England Patriots quarterback Tom Brady once famously missed a full season because of a serious left knee injury, and Carson Palmer had to be removed from a play-off game in 2006 after a sickening injury.
The latter injury forced the NFL to stop players from tackling below the knees of a defenseless player.
All of these changes haven't eased players' fears though.
USA Today surveyed 293 players from 20 NFL teams, and they asked what part of the body were players more concerned about injuring.
Knees were overwhelming placed at the top of the list with 46%, which was above the 24% who said the head and neck, with 26% of players not fearing any injury.
It's likely that the players are from teams that failed to make the play-offs, but regardless, this case study will act as a valuable reference for what is going on in the minds of current players.
Speaking to the paper, Chicago Bears running-back Michael Bush aired his feelings.
"Anytime you can avoid hits to the head it's great, but if you get hit in your knees, that's your career."
In a separate survey, it's also been found that 85% of 250 players would play in the Super Bowl with a concussion.
It seems the NFL might have a number of player safety issue on their hands in the off-season again.