THE EE WAS COMING DOWN THE 4TH FLOOR PREP PLANT STAIRS. HE STEPPED OFF THE LAST STEP AND TURNED AUSING A LOUD POPPING SOUND IN HIS LEFT KNEE. HE CONTINUED TO WORK. HE HAD A COMPLETE RECONSTRUC TION OF THE KNEE YEARS AGO. THE DR. FELT HE WOULD NEED SURGERY. ON 7-6-01 HE WENT IN AND HAD SURGERY. FIRST DAY OUT 7-6-01.