EE WAS CLIMBING OUT OF SHIPS HOLE WHEN FOOT SLIPPED OFF OF BENT RUNG ON LADDER. POPPING, SEVERE PAIN AND SWELLING TO LEFT KNEE AT 22:30-22:40. EE HAD TO CONTINUE TO CLIMB 25 - 30 FT. OUT OF HOLE. EE ALSO FELT KNOT BEHIND KNEE. EE HAD PREVIOUS INJURY TO LEFT KNEE 1994 OR 1995. PINS PLACED. EE OUT OF PLANT ON 09/30/07.