What is the definition of a flail chest?

A flail chest is defined as a section of the rib cage that is detached and moves in the opposite direction during breathing. This occurs when multiple adjacent ribs are fractured in such a way that a segment of the chest wall becomes free-floating. As a result, during inhalation, the affected segment can be sucked inward, while during exhalation, it bulges outward. This paradoxical movement disrupts normal breathing mechanics and significantly impacts respiratory function, often leading to serious complications, including inadequate ventilation and increased work of breathing.

Other definitions describe conditions such as lung collapse or simpler rib fractures, but they do not capture the specific mechanics and implications of flail chest, which is characterized by the abnormal movement of a section of the rib cage due to the loss of connection to the rest of the thoracic structure.