He collided with John Mabry last night trying to grab a throw to first. Mabry was attempting to beat out the throw and he collided into Casey's backside with his hip, and Casey suffered fractures in his lower back (left side). The report just came down a couple minutes ago.
http://sports.espn.go.com/mlb/news/story?id=2409937
Ouch.....all the best to Casey.