Fractures of five ribs that are simple and not associated with respiratory abnormalities or lung contusions are relatively minor and may be associated with chest pain that worsens with respiration, requiring pain relief and immobilization of the chest wall. However, if five ribs are fractured and breathing is impaired, then flail chest is a more serious condition. Shackle chest is a condition in which multiple ribs are fractured and the local chest wall softens without the support of the ribs, resulting in abnormal breathing, i.e., the chest wall sinks in during inhalation without expanding outward along with the rest of the chest, and expands outward during exhalation. Shackle chest can lead to severe respiratory and circulatory abnormalities, and hypoxemia can occur.