EMPLOYEE WAS CLEANING ROCK OFF THE TOP OF THE GRIDS THAT COVER THE CLEAN COAL FEEDER. HE STEPPED INTO ONE OF THE OPENINGS CAUSING HIM TO TWISTHIS RIGHT KNEE. HE CONTINUED TO WORK UNTIL 7/10 AT WHICH TIME HE VISITED THE DOCTOR AND WAS TOLDTO REMAIN OFF WORK UNTIL HE COULD SCHEDULE AN MRI.