Abstract: At about 1:00 p.m. on July 14, 1994, Employee #1 had been assigned to vacuum soot from the roof of an annealing oven using a vacuum hose attached to a truck. His employer, the U.S. Pipe and Foundry in Union City, CA, was in shut-down mode and Employee #1 was not performing his regular duties as a troughtender in the casting department. Employee #1 had rerouted the vacuum hose, and while he was walking to retrieve it he tripped as he stepped down from an I-beam member (approximately 8 inches high). His right knee cap was dislocated but he was able to pop it back in. Employee #1 was carried off on a stretcher. The plant nurse arrived and stabilized the leg. Shortly thereafter, an ambulance arrived and transported Employee #1 to the hospital. He was treated in the emergency room and released the same day. Employee #1 wore a leg brace for 5 weeks to stabilize his knee. He was off work for 8 weeks before he could return to his normal duties.