EE was installing 1/4"" metal plate over hole in the Mill Building motor control center room. EE stepped down into the hole 7' x 2 1/2' x 16"" to set the plate. While in the hole the EE twisted his body thus twisting his right knee causing a sharp pain. EE continued to work the entire day. EE woke up the next morning to come to work, but his knee was in pain. Sent to the Dr. for exam