Low Back Pain
Low back pain is very common and becomes more common as people age, affecting more than half of people over 60. It is one of the most common reasons for health care visits. Low back pain is very costly in terms of health care payments, disability payments, and missed work. However, the number of back injuries in the workplace is decreasing, perhaps because people are more aware of the problem and preventive measures have improved.
The spine (spinal column) consists of back bones (vertebrae). The vertebrae are covered by a thin layer of cartilage and separated and cushioned by shock-absorbing disks made of jelly-like material and cartilage. They are held in place by ligaments and muscles, which include the following:
These muscles help stabilize the spine. The abdominal muscles, which run from the bottom of the rib cage to the pelvis, also help stabilize the spine by supporting the abdominal contents.
Enclosed in the spine is the spinal cord (see Spinal Cord and see Overview of Spinal Cord Disorders). Along the length of the spinal cord, the spinal nerves emerge through spaces between the vertebrae to connect with nerves throughout the body. The part of the spinal nerve nearest the spinal cord is called the spinal nerve root. Because of their position, spinal nerve roots can be squeezed (compressed) when the spine is injured, resulting in pain.
The lower (lumbar) spine connects the chest to the pelvis and legs, providing mobility—for turning, twisting, and bending. It also provides strength—for standing, walking, and lifting. Thus, the lower back is involved in almost all activities of daily living. Low back pain can limit many activities and reduce the quality of life.
Common types of back pain include local, radiating, and referred pain.
Local pain occurs in a specific area of the lower back. It is the most common type of back pain. The cause is usually a muscle sprain, a strain, or another injury. The pain may be constant and aching or, at times, intermittent and sharp. Sudden pain may be felt when the cause is an injury. Local pain can be aggravated or relieved by changes in position. The lower back may be sore when touched. Muscle spasms may occur.
Radiating pain is dull, aching pain that travels from the lower back down the leg. It may be accompanied by sharp, intense pain. It typically involves only the side or back of the leg rather than the entire leg. The pain may travel all the way to the foot or only to the knee. Radiating pain typically indicates compression of a nerve root caused by disorders such as a herniated disk, osteoarthritis, or spinal stenosis (see Compression of the Spinal Cord). Coughing, sneezing, straining, or bending over while keeping the legs straight may trigger the pain. If pressure on the nerve root is great or if the spinal cord is also compressed, the pain may be accompanied by muscle weakness in the leg, a pins-and-needles sensation, or even loss of sensation and loss of bladder or bowel control (incontinence).
Referred pain is felt in a different location from the actual cause of the pain (see What Is Referred Pain?). For example, some people who have a heart attack feel pain in their left arm. Referred pain in the lower back tends to be deep and aching, and its exact location is hard to pinpoint. Typically, movement does not worsen it, unlike pain from a musculoskeletal disorder.
Most back pain is caused by disorders of the spine and the muscles, ligaments, and nerve roots around it or the disks between vertebrae. Often in such cases, no single specific cause can be identified. Whatever the cause, many factors such as fatigue, obesity, and lack of exercise can worsen back pain. Also, any painful disorder of the spine may cause reflex tightening (spasm) of muscles around the spine. This spasm worsens the existing pain. Stress may worsen low back pain, but how it does so is unclear.
Occasionally, back pain is due to disorders outside the spine, such as those of the kidneys and urinary tract, digestive tract, and blood vessels.
The most common cause of low back pain is
Muscle strains and ligament sprains may result from lifting, exercising, or moving in an unexpected way (such as when falling or when in a car accident). In addition to snatching a heavy weight from the ground, strains and sprains may be caused by pushing against an opposing lineman in football, suddenly turning to dribble after a rebound in basketball, swinging a bat in baseball, or swinging a club in golf. The lower back is more likely to be injured when a person's physical conditioning is poor and the supporting muscles of the back are weak. Having poor posture, lifting incorrectly, being overweight, and being tired also contribute.
Other common causes of low back pain include
Osteoarthritis (degenerative arthritis) causes the cartilage that covers and protects the vertebrae to deteriorate. This disorder is thought to be due, at least in part, to the wear and tear of years of use. People who repetitively stress one joint or a group of joints are more likely to develop osteoarthritis. The disks between the vertebrae deteriorate, narrowing the spaces between them and often compressing spinal nerve roots. Irregular projections of bone (spurs) may develop on the vertebrae and compress spinal nerve roots. All of these changes can cause low back pain as well as stiffness.
Compression (crush) fractures commonly develop when bone density decreases because of osteoporosis, which typically develops as people age. Vertebrae are particularly susceptible to the effects of osteoporosis. Compression fractures (which sometimes cause sudden, severe back pain) can be accompanied by compression of spinal nerve roots (which may cause chronic back pain). However, most fractures due to osteoporosis occur in the upper and middle back and cause upper and middle rather than low back pain.
A ruptured or herniated disk can cause low back pain. A disk has a tough covering and a soft, jelly-like interior. If a disk is suddenly squeezed by the vertebrae above and below it (as when lifting a heavy object), the covering may tear (rupture), causing pain. The interior of the disk can squeeze through the tear in the covering, so that part of the interior bulges out (herniates). This bulge can compress, irritate, and even damage the spinal nerve root next to it, causing more pain. A ruptured or herniated disk also commonly causes sciatica.
A Herniated Disk
What Is Sciatica?
Lumbar spinal stenosis is narrowing of the spinal canal (which runs through the center of the spine and contains the spinal cord) in the lower back. It is a common cause of low back pain in older people. Spinal stenosis also develops in middle-aged people who were born with a narrow spinal canal. It is caused by such disorders as osteoarthritis, spondylolisthesis, rheumatoid arthritis, ankylosing spondylitis, and Paget disease of bone. Spinal stenosis may cause sciatica as well as low back pain.
Spondylolisthesis is partial displacement of a vertebra in the lower back. It usually occurs in people who have a common bone birth defect (spondylolysis) that weakens part of the vertebrae. Usually, during adolescence or young adulthood (often in athletes), a minor injury causes a part of the vertebra to fracture. The vertebra then slips forward over the one below it. If it slips far, pain can result. Spondylolisthesis can also occur in older adults. People with spondylolisthesis are at risk of developing lumbar spinal stenosis.
Fibromyalgia (see Fibromyalgia) is a common cause of body pain, sometimes including low back pain. This disorder causes chronic widespread (diffuse) pain in muscles and other soft tissues in areas outside the lower back.
Less common causes that are serious include
A bulge (aneurysm) in the large artery in the abdomen (abdominal aortic aneurysm)
Certain digestive disorders, such as a perforated peptic ulcer, diverticulitis, and pancreatitis
Certain urinary tract disorders, such as kidney infections, kidney stones, and prostate infections
Certain disorders involving the pelvis, such as ectopic pregnancy, pelvic inflammatory disease, and cancer of the ovaries or other reproductive organs
Less common causes that are not as serious include shingles and several types of inflammatory arthritis, such as ankylosing spondylitis.
The doctor aims to identify any serious disorders. Because low back pain is often caused by several problems, diagnosing a single cause may not be possible. Doctors may only be able to tell that the cause is a musculoskeletal disorder and is not serious.
In people with low back pain, certain symptoms and characteristics are cause for concern. They include
A history of cancer
Pain for more than 6 weeks
Numbness, weakness in one or both legs, difficulty emptying the bladder (retention of urine), or loss of bladder or bowel control (incontinence)—symptoms that suggest nerve damage
Severe pain at night
Pain in people aged 55 or older without an obvious explanation (such as an injury)
Use of drugs that suppress the immune system, HIV infection or AIDS, use of injected drugs, recent surgery, or a wound—conditions that increase the risk of infection
Difficulty breathing, paleness, light-headedness, sudden sweating, a racing heartbeat, or loss of consciousness—symptoms that suggest an abdominal aortic aneurysm
Vomiting, severe abdominal pain, or stool that is black or bloody—symptoms that suggest a digestive disorder
Difficulty urinating, blood in the urine, or severe crampy pain on one side radiating into the groin—symptoms that suggest a urinary tract disorder
People should see a doctor immediately if they have fever or symptoms suggesting nerve damage, an abdominal aortic aneurysm, a digestive disorder, or a urinary tract disorder. People with most other warning signs should see a doctor within a day. If pain is not severe and people have no warning signs other than pain for more than 6 weeks, they can wait several days to see a doctor.
Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause and the tests that may need to be done (see Table: Some Causes and Features of Low Back Pain).
Doctors ask questions about the pain:
Certain characteristics of the pain can give clues to possible causes:
Pain in an area that is tender to the touch and is worsened by changes in position or weight bearing is usually local pain.
Pain on only one side of the back probably does not involve the spine.
Pain that radiates down the leg, such as sciatica, is usually caused by compression of a spinal nerve root.
Pain that is moderate or severe, is not affected by changes in position of the back, and is not accompanied by tenderness may be referred pain.
Pain that is constant, severe, progressively worse, and unrelieved by rest, particularly if it keeps the person awake at night, may indicate cancer or an infection.
The physical examination focuses on the spine and on evaluation of the nerves to the groin and legs to look for signs of nerve root compression. Signs of nerve root compression include weakness of one of the muscle groups in a leg, abnormal reflexes (tested by tapping the tendons below the knee and behind the ankle), decreased sensation in the groin area, retention of urine, and incontinence of urine or stool.
Doctors may ask the person to move in certain ways to determine the type of pain. For example, they may ask the person to lie flat, then lift the leg without bending the knee, and then stand and bend over. Doctors may also check a person's abdomen for tenderness or a mass, particularly in people over 55, who may have an aortic aneurysm. They examine the prostate in men by doing a digital rectal examination and the internal reproductive organs in women by doing a pelvic examination.
With information about the pain, the person’s medical history, and results of a physical examination, doctors may be able to determine as much as is necessary about the cause.
Some Causes and Features of Low Back Pain
Usually, no tests are needed because most back pain results from strains and sprains or other minor musculoskeletal disorders and resolves within 6 weeks. Imaging tests are often needed if
X-rays of the lower back show only the bones. They can help detect degenerative changes due to osteoarthritis, compression fractures, spondylolisthesis, and ankylosing spondylitis. However, magnetic resonance imaging (MRI) or computed tomography (CT) provides clearer images of bones and, particularly MRI, can show soft tissues (including disks and some nerves). MRI or CT is usually necessary when doctors are checking for disorders that cause subtle changes in bone and disorders of soft tissue. For example, MRI or CT can confirm or exclude the diagnosis of a herniated disk, spinal stenosis, cancer, and usually infection. These tests can also indicate whether nerves are being compressed.
If compression of the spinal cord is suspected, MRI is done immediately. Rarely, when results of MRI are unclear, myelography (see Tests for Brain, Spinal Cord, and Nerve Disorders : Myelography) with CT is required. Rarely, if cancer or infection is suspected, removal of tissue (biopsy) is necessary. Occasionally, electromyography and nerve conduction studies (see Tests for Brain, Spinal Cord, and Nerve Disorders : Electromyography and Nerve Conduction Studies) are done to confirm the presence, location, and sometimes duration and severity of nerve root compression.
The most effective way to prevent low back pain is to exercise regularly. Aerobic exercise and specific muscle-strengthening and stretching exercises can help.
Aerobic exercise, such as swimming and walking, improves general fitness and generally strengthens muscles.
Specific exercises to strengthen and stretch the muscles in the abdomen, buttocks, and back (core muscles) can help stabilize the spine and decrease strain on the disks that cushion the spine and the ligaments that hold it in place.
Muscle-strengthening exercises include pelvic tilts and abdominal curls. Stretching exercises include the sitting leg stretch and knee-to-chest stretch. Stretching exercises can increase back pain in some people and therefore should be done carefully. As a general rule, any exercise that causes or increases back pain should be stopped. Exercises should be repeated until the muscles feel mildly but not completely fatigued. Breathing during each exercise is important. People who have back pain should consult a doctor before beginning to exercise.
Exercises to Prevent Low Back Pain
Exercise can also help people maintain a desirable weight. Weight-bearing exercise can help people maintain bone density. Thus, exercise may reduce the risk of developing two conditions that can lead to low back pain—obesity and osteoporosis.
Maintaining good posture when standing and sitting reduces stress on the back. Slouching should be avoided. Chair seats can be adjusted to a height that allows the feet to be flat on the floor, with the knees bent up slightly and the lower back flat against the back of the chair. If a chair does not support the lower back, a pillow can be used behind the lower back. Sitting with the feet on the floor rather than with the legs crossed is advised. People should avoid standing or sitting for long periods. If prolonged standing or sitting is unavoidable, changing positions frequently may reduce stress on the back.
Sleeping in a comfortable position on a firm mattress is recommended. People who sleep on their back can place a pillow under their knees. People who sleep on their side should use a pillow to support their head in a neutral position (not tilted down toward the bed or up toward the ceiling). They should place another pillow between their knees with their hips and knees bent slightly.
Learning to lift correctly helps prevent back injury. The hips should be aligned with the shoulders (that is, not rotated to one side or the other). People should not bend over with their legs nearly straight and reach out with their arms to pick up an object. Instead, they should bend at the hips and knees. Bending this way keeps the back straighter and brings the arms down to the object with the elbows at the side. Then, keeping the object close to the body, they lift the object by straightening their legs. This way, the legs, not the back, lift the object. Lifting an object over the head or twisting while lifting increases the risk of back injury.
Stopping smoking is also recommended.
If a specific cause can be diagnosed, that disorder is treated. For example, antibiotics are used to treat a prostate infection. However, there is no specific treatment for musculoskeletal pain due to sprains or strains nor for many other musculoskeletal causes. But many general measures can help. Usually, these general measures are also used when a spinal nerve root is compressed.
For low back pain that has recently developed, treatment begins with avoiding activities that stress the spine and cause pain—such as lifting heavy objects and bending. Bed rest does not hasten the resolution of the pain, and most experts recommend continued light activity. Bed rest, if required to relieve severe pain, should last no more than 1 or 2 days. Longer bed rest weakens the core muscles and increases stiffness, thus worsening back pain and prolonging recovery. Spinal corsets and traction are not helpful. Traction may delay recovery.
Acetaminophen is usually recommended for pain relief unless inflammation is present. If inflammation is present, over-the-counter or prescription nonsteroidal anti-inflammatory drugs (NSAIDs—see Nonopioid Analgesics : Nonsteroidal Anti-Inflammatory Drugs) can relieve pain and reduce inflammation. If acetaminophen or NSAIDs do not provide sufficient pain relief, opioid analgesics (see Opioid Analgesics) may be required.
Muscle relaxants, such as carisoprodol, cyclobenzaprine, diazepam, metaxalone, or methocarbamol, are sometimes given to relieve muscle spasms, but their usefulness is controversial. These drugs are not recommended for older people, who are more likely to have side effects.
Application of heat or cold may help (see Treatment of Pain and Inflammation). Cold is usually preferred to heat during the first 2 days after an injury. Ice and cold packs should not be applied directly to the skin. They should be enclosed (for example, in plastic) and placed over a towel or cloth. The ice is removed after 20 minutes, then reapplied for 20 minutes over a period of 60 to 90 minutes. This process can be repeated several times during the first 24 hours. Heat, using a heating pad, can be applied for the same periods of time. Because the skin on the back may be insensitive to heat, heating pads must be used cautiously to prevent burns. People should not use a heating pad at bedtime to avoid the risk of falling asleep with the pad still on their back.
Massage may speed the resolution of musculoskeletal pain due to muscle spasm, strains, or sprains. Some studies suggest that acupuncture may have similar benefits, but others suggest little or no benefit. Spinal manipulation, done by chiropractors or some other doctors (such as osteopathic doctors), may also speed the resolution of pain due to muscle spasm, strains, or sprains. However, it may have risks for people with osteoporosis or a herniated disk.
After the pain has subsided, light activity, as recommended by a doctor or physical therapist, can speed healing and recovery. Specific exercises to strengthen and stretch the back and to strengthen core muscles are usually recommended to help prevent low back pain from becoming chronic or recurring.
Other preventive measures (maintaining good posture, using a firm mattress with appropriately placed pillows, lifting correctly, and stopping smoking) should be continued or started. In response to these measures, most episodes of back pain resolve in several days to 2 weeks. Regardless of treatment, 80 to 90% of such episodes resolve within 6 weeks.
Additional measures are needed for chronic low back pain. Aerobic exercise may help, and weight reduction, if necessary, is advised. If analgesics are ineffective, other treatments can be considered.
Transcutaneous electrical nerve stimulation (TENS) may be used (see Nondrug Pain Treatments). The TENS device produces a gentle tingling sensation by generating a low oscillating current. This current can block transmission of some pain sensation from the spinal cord to the brain. The current can be applied to the painful area several times a day for 20 minutes to several hours at a time, depending on the severity of the pain.
Sometimes a corticosteroid (such as dexamethasone or methylprednisolone) plus a local anesthetic (such as lidocaine) can be periodically injected into the epidural space—between the spine and the outer layer of tissue covering the spinal cord. These injections are more effective for sciatica caused by a herniated disk than for lumbar spinal stenosis. However, they are usually effective only for several days to weeks. Their main use is to relieve pain enough that an exercise program, which can provide long-term pain relief, can be started.
If a herniated disk is causing relentless or chronic sciatica, weakness, loss of sensation, or loss of bladder and bowel control, surgical removal of the disk (diskectomy) and sometimes part of the vertebra (laminectomy) may be necessary. A general anesthetic is usually required. The hospital stay is usually 1 or 2 days. Often, microsurgical techniques, with a small incision and regional spinal anesthesia (which numbs only a specific part of the body), can be used to remove the herniated portion of the disk. Hospitalization is not required. However, when the incision is small, the surgeon may not be able to see and therefore may not remove all fragments of the herniated disk. After either procedure, most people can resume all of their activities in a few weeks. More than 90% of people recover fully.
For severe spinal stenosis, a large part of a vertebra may be surgically removed to widen the spinal canal. A general anesthetic is usually required. The hospital stay is usually 4 or 5 days. People may need 3 to 4 months before they can resume all of their activities. About two thirds of people have a good or full recovery. For most of the rest, such surgery prevents symptoms from worsening.
When the spine is unstable (as may result from severe osteoarthritis), surgery can be done to fuse vertebrae together. However, fusion decreases mobility and may put additional stress on the rest of the spine.
Low back pain is very common and usually caused by a musculoskeletal disorder of the spine plus other factors, such as fatigue, obesity, and lack of exercise.
In young people, low back pain is rarely serious, and testing is usually unnecessary unless symptoms persist for weeks.
People who have warning signs or who are older than age 55 should see a doctor without delay.
Strengthening abdominal and back muscles can help prevent the most common types of low back pain.
For most low back pain, avoiding activities that stress the back, taking pain relievers, and sometimes applying ice or heat are sufficient treatment.
Prolonged bed rest and traction can delay recovery.