THE EE WAS PUTTING A PIECE OF MESH ON THE BOLTER AND STEPPED BACKWARD WHEN HE FELT SOMETHING SNAP IN HIS LEFT KNEE. THE EE WAS SEEN BY A MEDICAL PROVIDER AND RETURNED TO RESTRICTED DUTY ON 9-2 6-00. ON 10-02-00 THE EE WENT OFF OF WORK. FIRSTDAY OUT 10-02-00.