KERSEY BARN-WORKING ON #113 RAMCAR. STEPPED OFF PLASTIC BUCKET AND STEPPED ON RAIL DRAG CHAINED TO RAMCAR. WHEN STEPPING ON DRAG TWISTED RT KNEE. DRAG AND FLOOR HAD OILY RESIDUE. DID NOT START MISSING TIME UNTIL 3-15-01. ARTHROSCOPY-RT KNEETURN IN LATE DUE TO WAITING ON OPERATIVE REPORT FROM DR., RECEIVED 4-5-01.