ON 5-1-00 EMPLOYEE'S KNEE BUCKLED WHILE SWINGING A MAUL BREAKING BOULDERS. NO TREATMENT WAS SOUGHT AT THAT TIME. ON 5-24-00 EMPLOYEE'S KNEE LOCKED WHILE BENDING DOWN GETTING READY TO MOVE A RO CK. EMPLOYEE ENDED UP HAVING ARTHROSCOPIC SURGERY ON 6-1-00.