What condition is characterized by a fracture of two or more adjacent ribs allowing for free movement of the fractured segment?

Flail chest is a condition that arises when two or more adjacent ribs are fractured in multiple places. This results in the formation of a segment of the chest wall that becomes "flail" due to the loss of structural integrity. The fractured segment can move independently of the surrounding chest wall during respiration, leading to paradoxical movement where the flail segment depresses during inhalation and expands during exhalation, which can impair normal breathing patterns and decrease oxygenation.

In contrast, pneumothorax refers to the presence of air in the pleural space, rib contusion is a bruise to the rib without fractures, and costochondritis involves inflammation of the cartilage that connects a rib to the sternum, none of which involve the characteristic movement of fractured segments seen in flail chest. Understanding the mechanics of flail chest is crucial in medical assessments and treatments, as it may require immediate intervention to ensure adequate ventilation and prevent respiratory failure.