I been playing hockey for about 7 years, worst injury I had was a broken thumb, was first runner on penalty corner in training (usually play keeper) and got in the way of a shot, worst one I caused, I accidentally broke a girls ribs... We were playing on grass and I took and almighty kick at the ball, it lifted and smacked her right in the ribs.
Worst I've seen however was someone being carted off in a ambulance, they died later. It was a game on pitch before us, someone tripped and fell in front of a shot and took a stick in the throat. Freak accident, but definitly NOT a sport for pussies.