INJURED KNEELING TO OBSERVE AREA UNDER LONGWALL CRAWLER-TAIL. THE AREA HAD SOFT BOTTOM AND WAS CONSTRITED. HIS FOOT STUCK IN THE MUD AND AS HE LIFTED HIS LEG HE HEARD HIS LEFT KNEE POP. THIS W AS ORIGINALLY A FIRST AID ONLY INCIDENT. HE BEGAN LOSING TIME ON 3-24-00 DUE TO SURGERY.