Guys, you know why these so-called "blind side" injuries so extremely often cause concussions compared to "north-south" hits?
The head/neck can only bend so much, and if it's bent with force more than that there's sort of a "black-out angle" where your head stops turning (because otherwise your neck would be broken, you'd die or get paralysed and so on, and that's what happens sometimes in car/bicycle/motorcycle crashes, heavy machinery injuries and so forth). So when you get hit to your head east-west, your neck turns, and the more force in the hit the harder the head gets thrown against that stop, meaning the brain gets thrown against the cranium and itself.
That is why it's almost always it's a hook that knocks out boxers, that's why you want to hit the jaw from the side as a boxer (starting the maximum neck rotation), that's why boxers when hit with a hook try to "meet" the impact instead of following it, because even bending against the hit with your neck muscles and therefore probably adding to the direct impact, it still is less of an impact for the brain than the complete stop at what I called the knock-out angle.
This is sort of an oversimplification but I don't know how to explain it in regular English otherwise.
This is also really hard to prevent, but I've read that helm manufacturers in several fields/sports are working on safer helmets.
I'm a medical student, just writing this for credibility so I won't be disregarded immediately but this is something you can look up yourself.
But what would prevent most ice hockey concussions, is hockey players using the helmet in the correct way, and foremost the chinstrap. If your helmet flies off your head when you get hit, you did something wrong. Most guys have the chin strap hanging some 2 inches below the chin, well of course your helmet's not going to protect you when an impact won't keep it on right. i get really confused when guys with a history of concussions like Eric Lindros skating around like this:
You can see on the picture that he easily could take his helm off without unbuckling the chin strap. So congratulations, you ruined your career possibly because you couldn't take the uncomfort and uncoolness of having your chinstrap against your chin or at most 1 cm (1/3 of an inch) under it. I mean, it can't be less comfortable to have the chin strap 0,5 centimetres under your chin than 5 centimetres like he has on the picture, because either way it doesn't touch you.
