WHILE MAKING WAY TO THE MAINTENANCE TRUCK TO GET OUT OF A RAIN STORM, THE EMPLOYEE STEPPED ON A 3"" ROCK WHICH CAUSED HIM TO ROLL HIS ANKLE SIDEWAYS. WHEN HIS ANKLE ROLLED, HE BEGAN TO FALL TO THE GROUND & WHEN HE DID, HE ALSO HIT HIS RIGHT SHOULDER AGAINST THE MAINTENANCE TRUCK. HE WAS PUT ON RESTRICTED DUTY REQUIRING ONLY SIT-DOWN WORK.