EE WAS DOING ROUTINE WORK DURING THE SHIFT, WHICH INCLUDES WALKING CLIMBING STAIRS, BENDING ETC. SORENESS COND PAIN DEVELOPED INT HE BACK OF KNEE. EE STATED THAT HE DID NOT SLIP FELL TWIST OR DO ANYTHING THAT HE KNEW OF THAT CAUSED A PROBLEM ON MRI ON 11-14-01 INDICATED A PIECE OF LOOSE CARTILEDGE.