EE was helping another EE clean a material screen on a chute. The EE's did not have harnesses on when at a height of approx. 5 feet. The EE stuck EE's feet between the ladder and the structure, when EE went to replace EE's feet back on the ladder, EE lost balance. EE then fell approx. 4 feet and cushioned EE's blow with EE's right wrist, causing a fracture in hand.