An employee was loading an order of office chairs onto the second level of a semi-trailer truck, which required other employees to pass the chairs up to him so he could roll them back across plywood flooring that he was sitting on. He then attempted to stand up on the edge of the sheet of plywood when the plywood shifted and tilted vertically, causing him to fall approximately 4.5 feet to the wooden floor of the trailer. He landed on his back, head, and neck. His head struck the floor, bounced up, and struck the floor again as it came down. He sustained back, neck, and other bodily injuries, requiring hospitalization.