It is a serious, life-threatening chest injury often associated with underlying pulmonary injury and is most commonly seen in cases of significant blunt trauma. This typically occurs when three or more 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 costochondral 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– for flail chest to occur a significant impact is required, breaking the ribs in two or more places.