EE was climbing down into the hole of the revolving frame without the use of a ladder to weld a seam. When he got to the bottom, his (L) knee gave out on him. Reportable as of 8/25/05. EE did not seek medical treatment until 8/25/05 (1st visit to doctor): severe knee strain requiring the use of an immobilizer, crutches and sedentary work only.