Hockey is a violent sport.
That fact often gets lost as we try to keep up with the fastest game on two skates, but when budding talents like Sidney Crosby are taken away from us, it's a rude reminder of the career mortality of our NHL stars.
In recent seasons, the emphasis on concussion awareness and treatment has kept even more NHLers off the ice. As a fan, it's frustrating to see your team's best player in street clothes, but the safety of the players has to come first.
From Gary Bettman on down to each team's training staff, the NHL has done an good job of implementing guidelines of dealing with concussions and ensuring that players don't return until they're absolutely healthy.
On that somber note, let's take a look at a few hockey heroes who just haven't been able to stay on the ice.