What is the most common mechanism of injury (MOI) for flail chest?

Flail chest typically results from a significant force applied to the chest, leading to the fracture of multiple ribs in at least two places, creating a segment of the chest wall that moves independently from the rest during breathing. The most common mechanisms of injury associated with flail chest are falls, motor vehicle crashes, and assaults, as these incidents often involve high-impact trauma to the thoracic region.

Falls from heights or during activities can cause direct blunt force to the chest, while motor vehicle crashes involve high-velocity impacts that can easily lead to rib fractures and, as a result, flail segments. Additionally, physical assaults can involve blunt trauma that causes similar injuries. This pattern of injury reflects the substantial force required to produce rib fractures, emphasizing the greater risk posed by these particular incidents compared to less forceful mechanisms of injury, like those seen in sports injuries, industrial accidents, or circumstances of domestic violence, which may not exert the same level of force on the chest wall. Hence, falls, motor vehicle crashes, and assaults represent the most prevalent scenarios leading to this serious condition.