Lumbago affects the muscles of the lower part of the back, particularly after they have been strained or subject to some other injury which causes tearing of the muscle fibres. Lumbago causes disabling pain of a cutting or stabbing nature; this is due to an inflammatory condition in the connective tissues of the muscles associated with congestion of the blood vessels and consequent pressure upon the endings of the sensory nerves. The condition is also called "fibrositis" and is generally regarded to be of rheumatic origin. Lumbago does not respond readily to treatment, so that it is likely to affect future as well as present earning capacity and health; in addition, a number of occupations may lead to earlier onset of the condition and general spinal degeneration. Once a patient has had one attack of lumbago or sciatica, he is four times as likely to have another. In other cases, lumbago occurs in people with gout and the attacks take the place of an ordinary attack of gout.
Disorders of the lumbar region of the spine are the commonest of all lesions affecting the joints of the human body. Millions of work-days are lost to industry each year by back disorders and injuries. For example, a recent industrial survey mostly involving coal mining, found an average sickness absence of 12 weeks arising from all lumbar disorders including injuries.
In 2001, researchers published the results of two interviews, taken ten years apart, of more than 5,700 men and women. They found that those participants who reported feeling psychological distress when interviewed at age 23 were 2.5 times more likely to report having low back pain when interviewed at age 33.