© The Author(s) 2019. Purpose: The prevalence and distribution of air present in the leg in closed and low-grade open tibial shaft fractures are unknown on multidetector high-resolution computed tomography (CT). The purpose of this study was to determine the rate of surgical site infection (SSI) in cases where debridement was not performed in the area of air infiltration. Methods: Eighty-one closed and low-grade open tibial shaft fractures that underwent multidetector high-resolution CT on admission and were treated with an intramedullary nail were examined retrospectively. Results: Of the 36 Gustilo type I or II open fractures, all had local air around the fracture site (within 5 cm proximal and distal from the fracture center). Of these, 25 showed remote air (more than 5 cm away from the fracture center). The most frequent site of remote air was in the subcutaneous tissue, followed by the anterior compartment and deep posterior compartment. All open fractures were treated with local irrigation and debridement, regardless of the presence of remote air, followed by a reamed intramedullary nail. No SSI developed until bone union. Of the 45 closed fractures, 3 patients showed air in the leg on the CT. No debridement was performed for closed fractures. One patient who did not have air in the leg developed SSI. All fractures united eventually. Conclusions: In low-grade open tibial shaft fractures, air can spread far from the fracture site. Even in closed tibial shaft fractures, air can be identified in the leg. The debridement of the area of air infiltration, however, is not necessary for prevention of SSI.