Low back pain (LBP), sometimes referred to as lumbar pain or mechanical LBP, is defined as pain felt in the region of the lower back. This pain may originate at the lower back itself, or radiate to the lower back from another area of the body such as the upper back or pelvis. The type of pain felt at the low back varies, depending on its cause.

Second leading cause of work absenteeism

Low back pain has major implications in the United States. It is estimated that every year 15-20% of Americans suffer from LBP. It is the second leading cause of work absenteeism, behind respiratory illness. One-fifth of all workers compensation claims are due to LBP. In comparison to other medical conditions, it causes the greatest loss of productivity. It is one of the most frequent causes of hospitalization and the third most common reason to undergo a surgical procedure. It seems to affect men and women equally, and peaks in incidence during middle age. The pain is usually self-limited, with 80-90% resolving completely within six weeks. Another 5% of patients¹ LBP will resolve after 12 weeks, with the remaining 5% becoming chronic LBP sufferers. The prognosis for LBP in the acute phase is favorable, while the prognosis for chronic LBP tends to be worse.

Many possible causes

Low back pain has many possible causes. The majority of mechanical LBP is due to lumbar muscle strain or sprain. A small percentage of cases are due to age-related degenerative changes in the discs or of the bony joints of the lumbar spine. Herniated discs and even small compression fractures of the spine from osteoporosis, also cause LBP. Narrowing of the space around the spinal cord is another rare cause. Abnormal curves of the spine, like those of scoliosis or kyphosis of the lumbar spine may also result in pain.

Specific incident

Patients usually remember a specific incident that initiated their LBP. Common histories include lifting and/or twisting while lifting a heavy object, operating vibrating machinery (sandblasters, jackhammers), sitting for prolonged periods of time (as with truck drivers), or a history of trauma (motor vehicle accidents or a fall). Other risk factors, like bad posture, pregnancy, or a sedentary lifestyle may also contribute to the development of LBP. Unfortunately, only 1 in 5 patients will receive a precise diagnosis at the root of their LBP.

Musculoskeletal strains and sprains

Since the majority of cases are due to musculoskeletal strains and sprains, treatment is conservative. Certain "red flags," however, may indicate a more serious cause of LBP and a more urgent intervention. These symptoms include fever, unintentional weight loss, painful urination, and new bowel and bladder problems. If any of these red flags are present, the patient should seek medical attention promptly. Conditions such as bone infection, tumors (primary or metastatic) of the spine, or cauda equina syndrome may be present. This last condition is a true emergency that requires urgent surgical decompression of the spinal cord.

Previous history

Doctors will want to know if there is a previous history of illness, any congenital or metabolic disorders, or any previous traumas -- which includes a history of participating in athletics or the military. A typical physical exam looks for any neurological deficits (a change in the sensation of the lower extremities, or a change in the strength and motion of the back and lower extremities).

Medical Therapy

The goal of medical therapy is to relieve pain and to reduce any inflammation of the lower back. Inpatient therapy is not customary unless a more serious etiology is suspected. Imaging and invasive tests usually are not indicated unless there is a loss of neurological function, if any of the ³red flags² are present, or if pain remains unresolved for at least 6 weeks. Bed rest is no longer recommended, as the resultant de-conditioning of the body is more detrimental than beneficial.

Drug therapy is a common approach to relieving pain. Anti-inflammatory and muscle relaxants are the mainstay of treatment. Narcotics may be given, initially relieving the pain, but are associated with functional impairment. Oral steroid treatment is sometimes employed if there is significant mounts of inflammation. Epidural steroid injections at the site of pain have also been associated with temporary relief of symptoms, though long term benefits are still being investigated.

Typically, imaging is not conducted unless there is suspicion of a systemic infection, malignancy, a history of trauma, or if the body is weakened by chronic steroid use. X-rays of the lumbar spine are expensive and expose the reproductive organs to significant amounts of radiation. A CT or MRI is the study of choice for a more precise look at the structures of the spinal column and its surrounding tissues. If nerve damage is suspected, a test called an electromyogram (EMG) is conducted. This test uses needles to test the health of certain nerves along with the muscles they innervate.