EE HAD A DISCUSSION W/MANAGEMENT PRIOR TO ENTERING MINE ON DAY IN QUESTION ABOUT HOW FAVORING HIS BAD KNEE WAS CAUSING HIM TO HAVE TROUBLE W/HIS GOOD KNEE. HE GOES INTO THE MINE & GETS OUT OF JEEP HOLDING ONTO JEEP W/BOTH HANDS TO KEEP AS MUCH WEIGHT OFF HIS LEG AS POSSIBLE & HIS LEG JUST GAVE OUT. HE DID NOT SLIP, TRIP OR FALL. THERE IS NO DIAGNOSIS. POSSIBLE STRAIN/SPRAIN.