Q: Was it unusual that Rose injured his knee without being struck by another player or running into an object?
The most common way of tearing your ACL is non contact. It was the perfect storm for Derrick Rose to rupture his ACL. He’s missed much of the season because of his prior four injuries, and he’s only been back playing for three weeks, and it was in the last minute and a half of the game. He can’t possibly be at full strength because he missed so much time, so his muscles are more weak.
He went to make that sudden stop, and normally, if he was a little bit stronger, his muscles would have fired and kept his knee still. But his muscles were fatigued and they just gave out, and once they gave out, his knee started going into that position. Basically, he was coming in and stopped with such force that normally his muscles would have kicked in and stabilized his leg, but because his muscles were weak, his knee just kept going, and then ruptured the ACL. So it was really the fact that he wasn’t at 100 percent strength, and the fact that he was fatigued at the end of a game.
When you hear about skiers rupturing the ACL, it’s almost always in the afternoon, because someone like myself who is a recreational skier is not used to 8 hours of sports participation because we work all day. In the afternoon, my muscles are tired and fatigued, and that’s when my knee gets in that bad position.
(Edit: The entire article is a good all-around primer on ACL injuries and their treatment. I chose the blurb here to stoke the armchair surgeons roaming BaB.)