EMPLOYEE BEGAN MISSING WORK ON MARCH 8, 2004 DUE TO SWELLING IN HIS RIGHT KNEE. HE REPORTED THAT HE HAD NO KNOWLEDGE OF ANY INCIDENT AT WORK OR AT HOME THAT LED TO THE SWELLING. A MEDICAL OPIN ION FROM HIS PHYSICIAN STATED THAT THE CONDITION OF HIS RIGHT KNEE WAS RELATED TO HIS WORK AS A COAL MINER. THE DOCTOR ALSO NOTED THAT HE HAD BEEN TREATED FOR PROBLEMS OF BOTH KNEES FOR 20 YR