Employee was replacing a panel on a shuttle car when a piece of draw rock approx. 23"" X 8' long and 2 1/2 to 5"" thick fell between bolts and slid down EE's back before striking EE's left foot. Foot wasn't broken but EE was hospitalized in order to receive antibiotics through an IV. EE was released on 03/26/2017. EE returned to work on 03/27/2017.