Employee lifted a 75lb 55 gallon fiber drum of graphite onto a 4"" high scale instead of tipping and rolling the drum onto the scale. As EE lifted the drum 4"" to place on the scale EE pulled the back out. EE became immobile and an ambulance was called. EE was released for light duty the same day. EE was released for full duty without restrictions on 5/30/18 & reported back to work.