likely to eventually puncture the pleural sac and lung, possibly causing a pneumothorax. The concern about "mediastinal flutter" (the shift of the mediastinum with paradoxical diaphragm movement) does not appear to be merited. Pulmonary contusions are commonly associated with flail chest and that can lead to respiratory failure. This is due to the paradoxical motions of the chest wall from the fragments interrupting normal breathing and chest movement. Typical paradoxical motion is associated with stiff lungs, which requires extra work for normal breathing, and increased lung resistance, which makes air flow difficult. The respiratory failure from the flail chest requires mechanical ventilation and a longer stay in an intensive care unit. It is the damage to the lungs from the flail segment that is life-threatening. Causes The most common causes of flail chest injuries are vehicle collisions, which account for 76% of flail chest injuries. Another main cause of flail chest injuries is falling. This mainly occurs in the elderly, who are more impacted by the falls as a result of their weak and frail bones, unlike their younger counterparts who can fall without being impacted as severely. Falls account for 14% of flail chest injuries. Flail chest typically occurs when three or more adjacent ribs are fractured in two or more places, allowing that segment of the thoracic wall to displace and move independently of the rest of the chest wall. Flail chest can also occur when ribs are fractured proximally in conjunction with disarticulation of costal cartilages distally. For the condition to occur, generally there must be a significant force applied over a large surface of the thorax to create the multiple anterior and posterior rib fractures. Rollover and crushing injuries most commonly break ribs at only one point, whereas for flail chest to occur a significant impact is required, breaking the ribs in two or more places. This can be caused by forceful accidents such as the aforementioned vehicle collisions or significant falls. In the elderly, it can be caused by deterioration of bone, although rare. In children, the majority of flail chest injuries result from common blunt force traumas or metabolic bone diseases, including a group of genetic disorders known as osteogenesis imperfecta. Diagnosis Diagnosis is by physical examination performed by a physician. The diagnosis may be assisted or confirmed by use of medical imaging with either plain X ray or CT scan. Treatment Treatment of