Signs and symptoms
Two of the symptoms of flail chest are chest pain and shortness of breath.The characteristic paradoxical motion of the flail segment occurs due to pressure changes associated with respiration that the rib cage normally resists:

During normal inspiration, the diaphragm contracts and intercostal muscles pull the rib cage out. Pressure in the thorax decreases below atmospheric pressure, and air rushes in through the trachea. The flail segment will be pulled in with the decrease in pressure while the rest of the rib cage expands. During normal expiration, the diaphragm and intercostal muscles relax increasing internal pressure, allowing the abdominal organs to push air upwards and out of the thorax. However, a flail segment will also be pushed out while the rest of the rib cage contracts.Paradoxical motion is a late sign of flail segment; therefore, an absence of paradoxical motion does not mean the patient does not have a flail segment. The constant motion of the ribs in the flail segment at the site of the fracture is extremely painful, and, untreated, the sharp broken edges of the ribs are 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.
The knees should come in toward the chest while the person inhales, and exhale when the knees are lowered. This exercise can be done in 3 sets of 6–8 repetitions with a pause in between sets. The person should always make sure to maintain controlled breaths.Eventually, the person will be progressed to walking and posture correction while walking. Before the person is discharged from the hospital, the person should be able to perform mobility exercises to the core and should have attained good posture. Prognosis
The death rate of people with flail chest depends on the severity of their condition, ranging from 10 to 25%. A systematic review comparing the safety and effectiveness of surgical fixation versus non-surgical methods for the treatment of flail chest, reported that there was no statistically significant difference in the reported deaths between patients treated surgically and those treated non-surgically i.e. with conservative management methods. The results of the systematic review suggested that surgical intervention reduces the need for tracheostomy, reduces the time spent in the intensive care unit following a traumatic flail chest injury and could reduce the risk of acquiring pneumonia after such an event. Epidemiology
Approximately 1 out of 13 people admitted to the hospital with fractured ribs are found to have flail chest. References
External links
Rib Fractures & Flail Chest at Trauma.org – info, images, and video of paradoxical flail-segment motion