Bilateral fatigue fractures of the distal fibulae caused by a change of running shoes

A 26-year-old man sustained bilateral, symmetrical fatigue fractures of his distal fibulae while running in a 14-km road race. He had trained repeatedly over the course without developing any symptoms, but on the day of the race he lost one of his regular running shoes. He competed instead in old, borrowed tennis shoes. After running over a distance of 2 km, he felt pain about 4 cm above the distal end of both fibulae. Two weeks later, radiographs showed bilateral fractures. The change of footwear was the only identifiable factor in the causation of these fractures. Analysis by compression-loading showed that his usual running shoes absorbed twice as much energy and deformed five times as much as those used in the race.