Employee was in change house at the start of the shift, tripped over a bench, stumbled & fell. Didn't report incident to supv. Later that day, he mentioned it in passing, but no incident report taken. He was off the next day, worked the next day & then went to ER -Employee was placed on restricted duty 9/16(no OH work, climbing or twisting until recheck)Rtrn to reg duty 9/29