EE STOOD UP AND FELT A PAIN IN HIS LEFT ANKLE. EH DID NOT STRIKE OR BUMP ANYTHING. DIDN'T TWIST OR CATCH ANYTHING WITH HIS FOOT. HE SAYS THAT THERE WERE NO PROBLEMS PRIOR WITH HIS ANKLE AND SU PERVISOR IS NOT AWARE OF ANY PROBLEM. DIAGNOSED WITH ACHILLES TENDON AND PUT ON MODIFIED DUTY. IT IS NOT KNOWN WHAT CAUSED INJURY.