Low Back Pain
What is Low Back Pain?
The spine is a column of small bones, or vertebrae, that supports the entire
upper body. Most of the body's weight and stress is placed on the lumbar
vertebrae, which can be located by touching the lowest five bones protruding
from the spinal column. Low back pain generally occurs in this area. Below
the lumbar region is the sacrum, a shield-shaped bony structure that
connects with the pelvis at the sacroiliac joints. At the end of the spine
are two to four tiny partially fused vertebrae known as the coccus or tail
bone.
Vertebrae in the spinal column are separated from each other by small
cushions of cartilage known as intervertebral discs. Inside each disk is a
jelly-like substance called the nucleus pulposus, which is surrounded by a
fibrous structure. The disk is 80% water, which makes it very elastic. It
has no blood supply of its own, however, but relies on nearby blood vessels
to keep it nourished.
Each vertebra in the spine has a number of bony projections, known as
processes. The spinal and transverse processes attach to the muscles in the
back and act like little levers, allowing the spine to twist or bend. The
articular processes form the joints between the vertebrae themselves,
meeting together and interlocking at the facet joints.
Each vertebra and its processes surround and protect an arch-shaped central
opening. These arches, aligned to run down the spine, form the spinal canal,
which encloses the spinal cord-the central trunk of nerves that connects the
brain with the rest of the body. Each nerve root passes from the spinal
column to other parts of the body through small openings bounded on one side
by the disc and the other by the facets. When the spinal cord reaches the
lumbar region, it splits into four bundled strands of nerve roots called the
cauda equina (meaning horse-tail in Latin).
Back pain may be triggered by various problems that can occur along this
ridge of bone and disc. Injuries and small fractures can occur. As a person
ages, the discs thin; pressure on a weakened disk may cause it to rupture so
the nucleus pulposus protrudes out from the spinal column, a condition known
as a herniated disc. The facets can become misaligned or deteriorate. The
spinal canal itself can become narrowed, a condition called spinal stenosis.
If any of these conditions occur, the nerve roots passing between the discs
and facets may be stretched or pinched, causing pain.
The nerve most likely to cause trouble is the sciatic nerve; at some time,
up to 40% of people experience pain caused by compression of this nerve,
which branches from the nerve roots that descend off the spinal cord in the
lumbar and sacral areas. Each of the two branches of the sciatic nerve is
about as wide as a thumb and threads through the pelvis and deep into the
buttocks, then down the hip and along the back of the thigh to the foot. The
pain known as sciatica usually occurs on one side when a sciatic nerve has
been stretched or pinched, usually by a herniated disc, although spinal
stenosis or other vertebral abnormalities can also cause this pain. The
sensation of sciatica can vary widely-from a mild tingling to pain severe
enough to cause immobility. Some people experience sharp pain in one part of
the leg or hip and numbness in other parts. The pain increases after
prolonged standing or sitting and is aggravated by sneezing, coughing, or
laughing. If spinal stenosis is causing sciatica, patients may also
experience it after bending backwards or walking more than 50 to 100 yards.
Low back pain is usually defined as either acute or chronic. Physicians
diagnose low back pain as acute if it lasts less than a month and is not
caused by serious medical conditions. If the pain lasts over six months, it
is considered chronic low back pain; this constitutes only 1% to 5% of all
low back pain cases. Most cases clear up in a few days without medical
attention. A person should see a physician, however, under certain
circumstances: pain that lasts more than two weeks; very severe
pain-particularly if it awakens the person at night; pain that is increased
by lying down; pain accompanied by fever; weakness or numbness in legs,
feet, arms, or hands; an inability to control urination or defecation; and
neck pain or back pain in children.
What Causes Low Back Pain?
Sedentary Life Style
The causes of 85% of back pain cases are unknown. Most often, pain begins
with an injury, after lifting a heavy object, or after making an abrupt
movement. But the abrupt onset of pain following a single event or injury
may be the result of long-term sedentary living, obesity, poor posture,
badly designed furniture, stress, or a combination of any of these factors.
Although no definitive studies have been done to prove the relationship
between lack of exercise and low back pain, sedentary living is probably the
primary nonmedical culprit contributing to this condition. Experts offer as
theoretical evidence for this connection the many proven damaging effects of
sedentary life on other parts of the body. Obesity, associated with lack of
exercise, puts more weight on the spine and may increase pressure on the
vertebrae and discs. Lack of exercise results in muscle inflexibility, which
restricts the body's ability to move, rotate, and bend. Weak stomach muscles
increase the strain on the back and can cause an abnormal tilt of the
pelvis, and weak back muscles increase the load on the spine and the risk
for disc compression.
Exercise
Improper exercise instruction and inattention to mechanics can be sources of
sudden trouble; a single jerky golf swing or incorrect use of exercise
equipment, especially free weights, nautilus and rowing machines, can cause
serious back injuries.
Abnormalities of the Spine
A herniated disc, sometimes-but incorrectly-called a slipped
disc, is the most common cause of severe sciatica. (Sciatica can also be
caused by other problems, including spinal stenosis, inflammation, and the
piriformis syndrome-the entrapment of the sciatic nerve deep in the buttock
by the piriformis muscle. A disc in the lumbar area becomes herniated when
it ruptures or when the gelatin within the disc protrudes outward. If the
material breaks off or extends far enough out to press against the nerve
root, sciatic pain can occur. When an x-ray or scanner image shows
protruding or bulging disks in patients with low back pain, surgery is often
recommended. A recent study reported, however, that bulging and protruding
discs showed up on the scans of nearly two-thirds of people who had no back
pain at all.
Experts now generally believe that bulging, or even protruding, discs may be normal and do not necessarily indicate serious back problems
requiring surgical procedures. One expert suggested that discs might even swell in response to
stress and then contract again. However, disc material that extrudes, that is, it balloons into the area
outside the vertebrae or is fragmented from the disc itself, most likely is a cause of pain.
Spinal stenosis, the narrowing of the spinal canal, is usually caused by bone
overgrowth, which occurs mostly in the elderly who have degenerative arthritis, but it can
sometimes be caused by other problems, including infection and birth defects.
Osteoporosis is a disease of the skeleton in which the amount of calcium present in
the bones slowly decreases to the point where the bones become fragile and prone to fracture.
Fractures of the hip, wrist, or forearm are usually caused by falls or accidents, but spinal fractures
can occur simply as a result of pressure that compresses the vertebrae together. Osteoporosis is a
major cause of disability and death in the elderly. Between 25% and 60% of women over 60 years
old develop spinal compression fractures. Early spinal compression fractures may go undetected for
a long time, but after a large percentage of calcium has been lost, the vertebrae in the spine start to
collapse, gradually causing a stooped posture called kyphosis, or commonly, a dowager's hump.
Although this is usually painless, patients may eventually lose as much as 6 inches in height. If the
vertebrae collapse suddenly, however, pain is often severe, particularly over the affected vertebrae,
but pain can also radiate around the area.
Osteoarthritis occurs in joints where cartilage is damaged, then destroyed; in reaction
to this destruction, the bones associated with the joints develop abnormalities. Unlike some other
types of arthritis, such as rheumatoid arthritis, osteoarthritis is not systemic-that is, it does not
spread through the entire body, but rather concentrates in one or several joints where deterioration
occurs. (Rheumatoid arthritis can damage the joints in the neck but rarely effects the lower back.)
Osteoarthritis affects joints differently depending on their location in the body. It is commonly
found in the joints of the fingers, feet, knees, hips, and spine and only rarely in the wrist, elbows,
shoulders, or jaw. When it affects the spine, osteoarthritis may damage the cartilage in the discs, the
moving joints of the spine, or both. In any case, the patient can experience pain, muscle spasms,
and diminished mobility. The nerves may become pinched, causing pain and, in advanced cases,
numbness and muscle weakness.
Ankylosing spondylitis is a chronic inflammation of the spine that may
gradually result in a fusion of the spine causing the patient to stoop over. It can be quite mild,
however, and it rarely effects a person's ability to work. Symptoms include a slow development of
back discomfort, with pain lasting for more than three months. The back is usually stiff in the
morning; pain improves with exercise. It can be diagnosed using x-rays or scans. Ankylosing
spondylitis occurs mostly in young Caucasians in their mid-twenties. It was thought that the disease
affected mostly men, but about 30% of the cases are in women. It is probably hereditary; many
patients with ankylosing spondylitis have a protein on their cells called tissue-type HLA-B27.
About 20% of people with inflammatory bowel disease and about 20% of people with psoriasis
develop a form of ankylosing spondylitis.
Causes of back pain in young people
Scoliosis is an abnormal curvature of the spine that usually is discovered in childhood and is usually
due to defects present since birth. Juvenile chronic arthropathy is an inherited form of arthritis that
can cause pain in the sacrum and hip joints of children and young people; it used to be grouped
under juvenile rheumatoid arthritis but is now defined as a separate problem. In young athletes,
back pain is most likely to be caused by stress fractures in the spine (spondylolysis) or because of
an inborn exaggerated inward curve in the lumbar area (hyperlordosis). Sometimes back pain can be caused by problems in other organs, usually near the spine, which is
then called referred pain.
Who develops low back pain?
After the common cold, back pain is the most frequent reason for visits to doctors. At any given
time, about 31 million people in the U.S. suffer from back pain, and between 60% and 80% of
Americans experience it at some time in their lives. People who do not exercise are at particular risk
for low back pain, especially if they then embark on stressful unaccustomed activity, such as
shoveling, digging, or moving heavy items. Smokers are at higher risk, probably because smoking
decreases blood circulation, which is needed for nourishment of the discs. Pregnant women are
prone to back pain due to a shifting of abdominal organs, the forward redistribution of body
weight, and the loosening of ligaments in the pelvic area as the body prepares for delivery. Others at
higher than normal risk include older people, long-distance drivers, people who lift heavy objects
repetitively or operate heavy equipment, and tall people. Athletes are also prone to back injuries.
People with a family history of arthritis or disc abnormalities may also be at risk.
How is low back pain diagnosed?
Medical History
Because back pain can have so many different causes, it is very important to first rule out any other
medical conditions. A complete medical and family history should be taken that includes heart
problems, cancer, arthritis, and any other serious conditions. The patient should report previous
episodes of back pain as well as any history of injuries or accidents involving the neck, back, or
hips. The physician will generally ask about frequency, duration, and the nature of the pain, e.g.,
whether it is dull, piercing, throbbing, or burning. The patient should describe its onset and
whether the pain was triggered by an event, such as lifting a heavy object. The physician will need
to know what worsens the pain (for example, coughing, exercise, straining during bowel
movements, walking) and what relieves the pain (lying down, exercise). Other important symptoms
may include morning stiffness, problems in urination or defecation, and weakness or numbness in
the legs.
Physical Examination
Patients are asked to sit, stand, and walk in different ways-flat-footed, on the toes, and on their
heels. They will be requested to bend forward, backward, and sideways, to twist, and to lift their
leg straight up while lying down (which tests the tension of the sciatic nerve). The physician will
also move the patient's legs in different positions and bend and straighten the knees. To test nerve
function and reflexes, physicians will tap the knees and ankles with a rubber hammer. The
circumference of the calves and thighs may be measured to look for muscle deterioration. The
physician may touch parts of the body lightly with a pin, cotton swab, or feather to test for
numbness and nerve sensitivity.
Imaging Techniques
Imaging techniques, including x-rays and magnetic resonance imaging (MRI) and computerized
tomography (CT) scans, have fallen out of favor for routine use. Scans are very expensive, and
HMOs and insurance companies are increasingly reluctant to pay for them. Many experts believe
that their routine use for back pain has lead to an increase in the number of operations on the back,
some of which have been unnecessary and even dangerous. A recent study suggested that the
majority of all adults have bulging or protruding vertebrae discs, even if they have no back pain at
all, so that abnormalities in people who do have back pain may simply be a coincidence rather than
an indication for treatment. People with low back pain should have x-rays or scans done only under
certain circumstances, such as pain that lasts more than a month, very severe pain, numbness,
muscle weakness, accidents that might involve the vertebrae, a history of cancer, or the presence of
fever. If these conditions exist, usually an x-ray is used first, and then, if results are inconclusive,
either a CT or MRI scan. CTs and MRIs have largely replaced an older, more invasive imaging test
known as a myelogram. A local anesthetic is applied and then a dye is injected into the spinal canal,
which allows visualization of the spinal canal. The patient must remain still for several hours after
the x-ray to avoid severe headaches. A discography is an x-ray of the disc and also uses a spinal
injection; this can be more painful than a myelogram. MRI and CT scans do not require spinal
injections and are not painful.
How is low back pain treated?
Back pain attributed to medical conditions, such as arthritis, osteoporosis, or pregnancy, either
resolves when the condition does or is treated as part of the overall therapeutic plan. When low back
pain is not caused by a medical condition, about 90% of people recover within a month without any
treatment at all. In spite of this encouraging statistic, back pain is the third most common reason for
surgery and costs the country up to $50 million each year in medical and disability benefits. Such a
discrepancy recently triggered a major government investigation into why such a minor problem
ends up so often in the operating room. This resulted in some new guidelines set by the Agency for
Health Care Policy and Research recommending very moderate treatment options for most cases of
low back pain.
General Guidelines for Treatment of Acute Low Back Pain
At the onset of acute low back pain, the patient should take an over-the-counter pain killer and lie
down in a comfortable position. Lying on the side or back with knees bent supported by a pillow
relieves the stress on the back. Many people find that alternating ice packs and heating pads at about
twenty-minute intervals is helpful in relieving the pain. Ice packs should be applied first.
Bed rest is usually not needed; if it is, most experts recommend staying in bed no longer than a
couple of days. A recent study reported, however, that even two days may be too long. In the
study, people who avoided bed rest altogether and simply tried to resume normal activities, without
strain or stretching exercises, recovered more quickly than those who were in bed for even as short
a period as two days. Those who are in bed a week or longer do even worse. Long-term bed rest
results in loss of muscle tone and bone strength, increases susceptibility to blood clots, and
produces depression and lethargy. Traction probably has no benefit and may be harmful.
The speed at which patients resume activity can be guided by their level of pain. People usually
recover from a strained back or a mildly herniated disc in a few of days. It may take, however, as
long as six weeks to fully recover from back pain, particularly if it is due to sciatica. At that time, if
the pain has not been relieved, other measures may be needed.
Medication
NSAIDs and Acetaminophen. The most useful pain killers for back pain are nonsteroidal
anti-inflammatory drugs (NSAIDs). These drugs block prostaglandins, substances that dilate blood
vessels and cause inflammation. Some experts recommend aspirin as the first choice. Short term use at low doses is beneficial and has low risk. Long time use for chronic
back pain or arthritis can cause problems, especially gastrointestinal disorders and kidney damage
(which is nearly always reversible after stopping the drug). Although aspirin is commonly cited as
the chief culprit for stomach distress, a major study found that, in moderate doses, aspirin had less
severe side effects than other NSAIDs, and in high doses (more than 3900 mg per day), the side
effects were the same. Ibuprofen has also been shown to have less gastrointestinal side effects,
although it has one of the highest risks of the NSAIDs for kidney problems.
Acetaminophen (Tylenol, Anacin-3, Panadal, Phenaphen, Valadol, and other brands) is the
over-the-counter alternative to NSAIDs. One study reported that acetaminophen was as effective as
an anti-inflammatory drug in relieving chronic pain. Still, many patients report less pain relief with
acetaminophen than with NSAIDs. Acetaminophen can be used alone or in combination with
NSAIDs with some success. Liver and kidney damage, however, are potential serious side effects
of acetaminophen. A recent study showed that taking one tablet daily for a year doubled the risk of
kidney disease, and that amounts as low as 4 to 10 grams daily increased the risk of liver damage in
people who hadn't eaten much for prolonged periods due to illness. Experts recommend taking no
more than 8 extra-strength tablets each day.
Steroids. A one-time injection of a steroid into the area around the spinal column may be an
effective way to short-cut the back pain until the body heals itself, although studies are conflicting.
It is not a cure; steroids are generally useful for reducing inflammation. Two reviews of studies
found that use of steroids had no benefit, but other recent studies support this treatment, finding it
more beneficial than the use of a local anesthetic.
Other Medications. Although physicians may prescribe muscle relaxants such as cyclobenzaprine
(Flexeril), some experts believe that relaxing muscle spasm may actually be harmful, because the
tensed back muscles may be serving a purpose by protecting the damaged disk or vertebrae.
Injections of local anesthetics are occasionally used and can be helpful for temporary relief of severe
pain, but experts now strongly advise against heavy-duty prescription pain killers, such as
morphine and codeine, which they believe do more harm than good.
Exercise
In a recent study, therapeutic exercises to improve flexibility did not hasten recovery from acute low
back pain any better than simply gradually resuming normal activity, letting pain be the guide for
how much movement is achieved. In fact, recovery was slower in the therapeutic exercise group
and these patients required more physician care. In general, normal activity should be resumed in a
gradual fashion as soon as the patient feels ready, reserving therapeutic exercises until the acute pain
has resolved. An incremental aerobic exercise program is less stressful than stretching or exercises
strengthening the trunk muscles. Experts suggest that walking, stationary biking, swimming, and
even light jogging may begin within two weeks of symptoms, but patients should never force
themselves to exercise if, by doing so, pain increases.
Exercise appears to be the best approach in treating chronic low back pain. In a study of patients
who had suffered back pain for an average of 18 months, those who were assigned 8 one-hour
exercise sessions over four weeks improved in nearly every area, including reduced pain and
increased capacity, compared to the patients who did not exercise. Another study of 250 men and
women found the same results. Swimming, bicycling, and walking are all good exercises that can
strengthen muscles in the abdomen and back without over straining the back. People vulnerable to
back pain should avoid exercises or activities that put undue stress on the lower back or require
sudden movements, such as football, rowing, ballet, and weight lifting. Jogging is usually not
recommended, at least not initially. Traditional standard sit-ups can be harmful, but bent-knee sit
ups can build stomach muscles without stress to the lower back.
Surgery
It is extremely important to get a second opinion before agreeing to surgery for low back pain.
Surgery does not always improve outcome and in some cases can make the condition worse. One
study showed there was no difference in employment at the end of a year between people who
underwent surgery and those who did not, although the surgical group experienced less pain.
Evidence of a herniated disk and nerve compression is not an automatic indication for surgery.
Surgery is almost always advised, however, if sciatic pain is accompanied by incontinence, which
indicates that the bundle of nerves at the end of the spinal cord known as the cauda equina are being
pinched. In such cases, an operation should be performed as soon as possible to avoid permanent
damage. Other indications include a progressive weakening in the legs and evidence of some
physical abnormality of the spine, such as a bone spur or spinal stenosis due to bone growth. A
patient should be sure that the surgeon has had significant experience with any procedure to be
performed.
Laminectomy is an operation that cuts away a piece of vertebrae and removes
damaged parts of the disk. If bone growth is causing the problem, as in spinal stenosis, the surgeon
will shave away the bone in order to decompress the nerve. Laminectomy requires general
anesthesia and a two or three day hospital stay. Recuperation takes up to six weeks. Although it
often brings immediate relief from pain, there are small risks to the operation and it is not always
successful. Some recurrence of back pain and sciatica occurs in half to two-thirds of postoperative
patients.
Automated percutaneous discectomy (APD) requires the
insertion of a thin tube into the diseased disc. The tube has a device at the tip that cuts away some of
the nucleus pulposes and a vacuum that then sucks this gelatinous matter out, relieving pressure on
the nerve. Lasers may be used for this procedure, although recovery takes longer in such cases. The
disadvantage to this procedure is that surgeons cannot observe the nerve root itself, so they cannot
tell if the fragments removed are the source of the trouble, nor can they locate and remove any
matter that has gone beyond the disk and entered the spinal canal.
Patients best suited for this procedure appear to be those whose pain has lasted less than a year and
who are unable to undergo more invasive procedures.
For herniated discs not treatable by other methods, the
procedure chemonucleolysis (CNL) is effective in some cases. It is not warranted for any other type
of low back problem. CNL still requires general anaesthesia and a brief hospital stay, but it is less
traumatic than laminectomy, and patients may be able to return to work sooner. It is somewhat less
effective than discectomy. The physician injects the herniated disk with
chymopapain, an enzyme
made from the papaya. Chymopapain is a common ingredient in meat tenderizers and it softens the
nucleus purposis-the disc's gelatinous filling, thus reducing the bulge and relieving the pressure on
the sciatic nerve. It may take days or even months for the enzyme to relieve the pain completely, but
in 17 out of 20 studies, CNL was found ultimately to be as beneficial as
laminectomy. In one study
it relieved pain in 75% of patients. Risks include severe allergic reactions to
chymopapain, which
occur in about 1% of people, and nerve damage if the enzyme leaks out of the disc.
Transcutaneous Electric Nerve Stimulation
Transcutaneous electric nerve stimulation (TENS) uses low-level electrical pulses to suppress back
pain. The standard approach is to give 80 to 100 pulses per second for 45 minutes three times a day;
patients are barely aware of the sensation. However, studies have not found this treatment to be any
more beneficial than conservative therapy.
How is low back pain prevented?
It is best not to stand for long periods of time, but if it is necessary, one should walk around as
much as possible and maintain good posture. This means keeping the ears, shoulders, and hips in a
straight line with the head up and stomach pulled in. If a low stool is available, alternating resting
each foot on it may relieve pressure. Wearing shoes without heels, preferably with cushioned soles,
prevents the back from arching and absorbs shock.
Sitting puts the most pressure on the back, and driving for long periods in a vehicle increases the
stress. Chairs should either have straight backs or low-back support. If possible, chairs should
swivel to avoid twisting at the waist, have arm rests, and adjustable backs. While sitting, the knees
should be a little higher than the hip, so a low stool or hassock is useful to put the feet on. When
driving, move the seat as far forward as possible to avoid bending forward. A small pillow or rolled
towel behind the back helps relieve pressure while either sitting or driving.
Be sure to have a firm mattress. If the mattress is too soft, a 1/4-inch plywood board can be put
between the mattress and box spring. On the other hand, some people have experienced morning
back ache from a mattress that is too hard. The back is the best guide.
Although exercise is important for recovery from back pain, there are no studies proving that exercise prevents back pain in the first place. Many experts believe, however, that by strengthening the muscles in the trunk, the spine is better protected against injury. Generally, preventive exercise objectives include abdominal strengthening, increasing lower back mobility, hip flexibility, flexibility of hamstring muscles and tendons (those at the back of the thigh), and back muscle strength and endurance. Exercises in which the lower back is under pressure, such as leg lifts done in a prone (face-down) position, should be avoided until the back muscles are well-toned. Straight leg sit-ups and leg curls using exercise equipment should also be avoided unless back muscles are well-strengthened.
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