EE WAS ROTATING A PIECE OF MACHINERY BY HAND USING PIPE WRENCH AND PIPE TO CLEAR A BLOCKAGE. PIPE WRENCH SLIPPED ON A SHAFT AND TOOL ROTATED DOWNWARD STRIKING EE'S RIGHT KNEE. EE'S KNEE WAS SORE AND X-RAYED AT LOCAL HOSPITAL. EE WAS RELEASED TO LIGHT DUTY AND UNDERWENT PHYSICAL THERAPY FOR A DISLOCATED PATELLA. ON 8-29-03 EE UNDERWENT ORTHOPEDIC SURGERY.