An employee was helping an operator close a barbed wire gap. The gap was stretched across some digging mats (placed that morning) on a temporary crossing that was used to contain cattle. While attempting to close the gap, he walked backwards on the construction mats and stepped in a hole between them. He then fell backwards, landing on his right hip. The mats were uneven and were elevated right where he landed. He was hospitalized with a broken right hip/femur, requiring surgery.