On 6/25/12 EE was going down a ladder on the inside of a compartment to the lowest level module. He was going to step onto the floor, but there was some build up of material and he felt his ankle twist. EE did not report any pain at this time and continued work. Reported discomfort on 7/16/12. Taken to The Work Clinic for Xray. Found to have a sprained ankle.