What is a rib fracture? A rib fracture is a break in one of the bones that compose the rib cage. Ribs may be fully broken or partially broken (cracked). When a rib is completely broken, the edges of the bones pose a danger of damaging or tearing internal organs, such as the lungs, liver or spleen, as well as blood vessels. Bone fractures, including fractures of the rib, are most commonly caused by trauma, such as fall or a motor vehicle accident. Certain medical conditions, such as osteoporosis, weaken the bones and increase the risk of a rib fracture. Cancer that has spread to the bones of the rib cage can also predispose to the development of a rib fracture. In some cases of weakened bones, even violent coughing may be sufficient to cause a rib fracture. Anyone can sustain a rib fracture or other type of bone fracture. However, older people with more brittle bone structure are at a higher risk of suffering fractures from trauma that would not result in fracture in a younger person. Rib fractures can pose serious health risks, including punctures of the lungs or other internal organs or the rupture of major arteries. Seek immediate medical care (call 911) if you believe you may have a rib fracture.