An employee was moving retired crossarms and wire from the back of a bucket truck into a dumpster while standing on the utility box. The employee pulled a partial crossarm with braces that did not immediately come free; it was approximately 5 feet and 9 inches long and 4 inches by 6 inches thick. When the crossarm came free, the momentum caused the employee to fall approximately 5 feet to the ground, resulting in a fractured left elbow.