A couple points related to above posts (in no particular order):
A) Just because a guys gets "KO'd" doesn't mean it is a concussion. Plus - define KO..... If a guy gets hammered by a punch (or multiple punches), and goes down - people watching on TV, or play by play guy says it was a knockout - is it really? Most of the time the guy gets back up and is good to go (wether it be next shift, next game, etc.) A true "KO" - see when a boxer gets dropper and is literally out cold for however many seconds. I honestly don't believe Orr was truly knocked out, stunned maybe. A true knock out is when Fedoruk got beat bad a while back, or Kypreos.
B) A lot of these tough guys being put on LTIR or have career threatening injuries - are usually not injured from absorbing a punch(es). Orr - face hit ice - large man landed on top, Boogard (I think) hurt his shoulder originally (someone did, maybe not him), a guy like Hall, though definately not an enforcer, severely sprains an ankle as a result of falling during a fight (this could happen to anyone).
C) You have to start to question having guys like Boogard, MacIntyre, maybe a guy like Westgarth too (best 2 or 3 examples I can come up with) in lineups. These guys are really not even 4th liners. They really aren't NHL standard average skaters even. There are scrappers like Thornton, Brown, Lucic who can thrown bombs, but still play. Having a guy 6'8", 275lbs (just an example) to sit on the bench "just in case" is kind of getting useless in today's game. Plus these guys are potentially a danger to other players. Yes, I know fighters know the risks involved, but this isn't the 1970's/80's anymore. This is coming from me, who usually enjoys a good fight, but there is a time and place for it.
D) Someone mentioned better fitting helmets. It's not the fit, it's if the players choose to wear it properly. Plus how this help the fighter who gets his helmet taken off by the other guy, or a punch, or guys who "go buckets off"?????
It's really too bad they don't make players anymore like Cam Neely, Wendel Clark, etc. Sure, I can score 30+ goals, and beat the snot out of everyone in between those goals!