**Question:** True about Flail chest -

A. It is a severe rib fracture causing instability and motion of adjacent ribs.
B. It is a minor injury, requiring no medical intervention.
C. It is a rare condition involving a single rib fracture.
D. It is a complication of lung transplantation.

**Correct Answer:** A. It is a severe rib fracture causing instability and motion of adjacent ribs.

**Core Concept:** Flail chest is a term used to describe a specific type of severe rib fracture that results in instability and abnormal motion of adjacent ribs. This condition can significantly impair lung expansion and ventilation, leading to hypoxia and respiratory distress.

**Why the Correct Answer is Right:** Flail chest occurs due to multiple rib fractures, typically involving three or more adjacent ribs, which disrupts the normal rib cage structure and function. When these fractured ribs move abnormally, it causes lung compression, displacement, and impaired expansion, contributing to respiratory distress.

**Why Each Wrong Option is Incorrect:**

B. Flail chest is not a minor injury and requires appropriate medical management, not dismissing its severity.
C. Flail chest involves multiple fractured ribs and is not limited to a single rib fracture.
D. Flail chest is a clinical manifestation, not a complication, of lung transplantation.

**Clinical Pearl:** Flail chest management involves early intubation and mechanical ventilation to maintain adequate gas exchange and prevent further lung injury. Additionally, pain control and immobilization of the affected ribs (e.g., using rib fracture brace) are essential components of treatment. Early recognition and management are crucial to reduce morbidity and mortality associated with this potentially life-threatening condition.