Close-Range Fire Inflicting Behind Armor Blunt Trauma: Case-Series and Implications for Battlefield Care.

Behind armor blunt trauma (BABT) is a non-penetrating injury caused by energy transfer and rapid deformation of protective body armor. Although modern military body armor is designed to prevent penetrating trunk injuries, high-energy projectiles can produce a significant energy transfer to tissues behind the armor and inflict injuries such as fractures or organ contusions. However, knowledge of BABT is limited to biomechanical and cadaver modeling studies and rare case reports. We report two cases of BABT resulting from close-range fire and discuss the potential implications for triaging patients with BABT in battlefield scenarios. In the first case, a 19-year-old male soldier sustained a single close-range 5.56-mm assault rifle gunshot to his chest body armor. The soldier initially reported mild pain in the parasternal region and assessment revealed a 4 cm × 3 cm skin abrasion. Following emergency department evaluation, the soldier was diagnosed with a non-displaced transverse fracture of the sternal body. In the second case, a 20-year-old male sustained five machine gun bullets (7.62 mm) to his body armor. Computed tomography of the chest revealed pulmonary contusions in the right lower and middle lobes. Both soldiers achieved full recovery and returned to combat duty within several weeks. These cases highlight the potential risks of energy transfer from high-velocity projectiles impacting body armor and the need for frontline providers to be aware of the risk of underlying blunt injuries. Further reporting of clinical cases and modeling studies using high-velocity projectiles could inform recommendations for triaging, evacuating, and assessing individuals with BABT.