Back pain is pain felt in the back that usually originates from the muscles, nerves, bones, joints or other structures in the spine. However, internal structures such as the gallbladder and pancreas may also refer pain to the back. Most back pain is felt in the lower back. The remainder of this article considers back pain in all regions. The onset of back pain may be acute or chronic. It can be constant or intermittent, stay in one place or radiate to other areas. It may be characterised by a dull ache, or a sharp or piercing or burning sensation. The pain may radiate into the arms and hands as well as the legs or feet, and may include symptoms other than pain. Examples of these symptoms may include tingling, weakness or numbness in the legs and arms, indicating injury to the nerves. Back pain is common and disabling. In the U.S., acute low back pain (also called lumbago) is the fifth most common reason for physician visits. About nine out of ten adults experience back pain at some point in their life, and five out of ten working adults have back pain every year. Low back pain causes 40% of missed days of work in the United States. Additionally, it is the single leading cause of disability worldwide.
