ON 01-17-00 EMPLOYEE WAS WORKING UNDER A 777 END DUMP IN THE SHOP. AS HE STOOD UP FROM A SQUATTING POSITION, HE TWISTED HIS RIGHT KNEE. AT THAT TIME THE REPORTED INJURY WAS TREATED AS A FIRST- AID CASE. ON 01-19-00 THE SAFETY SUPERVISOR WAS INFORMED THAT EMPLOYEE HAD DEVELOPED COMPLICATIONS CONCERNING THE INJURY. HE WAS TRANSPORTED TO SEEK PROFESSIONAL CARE, WHERE HE WAS DIAGNOSED