An In-Depth Overview of Low Back Pain

A Reference for Patients


Theodore R. Fields, MD, FACP

Theodore R. Fields, MD, FACP

Attending Physician, Hospital for Special Surgery
Professor of Clinical Medicine, Weill Cornell Medical College

  1. How Common Is Low Back Pain?
  2. What Are the Causes of Low Back Pain?
  3. Importance of An Accurate Diagnosis
  4. Mechanical Low Back Pain
  5. Inflammatory Low Back Pain
  6. Low Back Pain Caused by Infection
  7. Fractures and Low Back Pain
  8. Low Back Pain and Cancer
  9. Referred Pain to the Lumbar Spine
  10. Chronic Low Back Pain
  11. When Are Certain Diagnostic Tests Necessary?
  12. Treatment Options for Acute Low Back Pain
  13. Surgery for Low Back Pain
  14. Summary
  15. Useful Links and References

I. How Common Is Low Back Pain?

Two out of every three adults suffer from low back pain at some time. Back pain is the #2 reason adults visit a doctor, and the #1 reason for orthopaedic visits. It keeps people home from work and interferes with routine daily activities, recreation, and exercise. The good news is that for 9 out of 10 patients with low back pain, the pain is acute, meaning it is short-term and goes away within a few days or weeks. There are cases of low back pain, however, that take much longer to improve, and some that need evaluation for a possible cause other than muscle strain or arthritis.

Symptoms may range from muscle ache to shooting or stabbing pain, limited flexibility and/or range of motion, or an inability to stand straight.


What Structures Make Up the Back?[1]

The back is an intricate structure of bones, muscles, and other tissues that form the back, or posterior part of the body’s trunk, from the neck to the pelvis. At the center is the spinal column, which not only supports the upper body’s weight but houses and protects the spinal cord — the delicate nervous system structure that carries signals that control the body’s movements and convey its sensations. Stacked on top of one another are about 30 bones — the vertebrae — that form the spinal column, also known as the spine. Each of these bones contains a roundish hole that, when stacked in line with all the others, creates a channel that surrounds the spinal cord. The spinal cord descends from the base of the brain and extends (in the adult) to just below the rib cage.

Vertebrae are bones that form the spinal column. Small nerves (“roots”) enter and come out from the spinal cord through spaces between the vertebrae. Because the bones of the spinal column continue growing long after the spinal cord reaches its full length in early childhood, the nerve roots to the lower back and legs extend many inches down the spinal column before exiting. This large bundle of nerve roots was dubbed by early anatomists as the cauda equina, or horse’s tail. The spaces between the vertebrae are maintained by round, spongy pads of cartilage called intervertebral discs that allow for flexibility in the lower back and act much like shock absorbers throughout the spinal column to cushion the bones as the body moves. Bands of tissue known as ligaments and tendons hold the vertebrae in place and attach the muscles to the spinal column.

Starting at the top, the spine has four regions:

  • The seven cervical or neck vertebrae (labeled C1-C7)
  • The 12 thoracic or upper back vertebrae (labeled T1-T12)
  • The five lumbar vertebrae (labeled L1-L5), which we know as the lower back, and
  • The sacrum and coccyx, a group of bones fused together at the base of the spine.

Image courtesy of www.SpineUniverse.com

II. What Are the Causes of Low Back Pain?

The vast majority of patients experience back pain because of mechanical reasons. They strain a muscle from heavy lifting or twisting, suffer a sudden jolt in a car accident, experience stress on spinal bones and tissues resulting in a herniated disc, or suffer from osteoarthritis, a potentially painful degeneration of one or more joints. However, to choose the safest and most effective therapy, doctors need to consider the full spectrum of possible underlying issues, such as inflammatory conditions, infection, fractures, as well as some serious conditions unrelated to the back that radiate pain to the back.

III. Importance of An Accurate Diagnosis

The doctor will need to take a careful medical history and do a physical exam to look for certain red flags that indicate the need for an x-ray or other imaging test. In most cases, however, imaging such as x-ray, MRI (magnetic resonance imaging), or CT (computerized tomography) scan is unnecessary.

The doctor will look for certain clues in a patient’s medical history to reach a diagnosis. The character of the pain is telling. A common pain is due to sciatica, a condition in which a herniated or ruptured disc presses on the sciatic nerve, which extends down the spinal column to its exit point in the pelvis and carries nerve fibers to the leg. This compression causes pain in the lower back combined with pain, and often numbness, which radiates through the buttocks and down one leg to below the knee. In the most extreme cases, the patient experiences weakness in addition to numbness and pain, which suggests the need for quick evaluation.

A shooting or tingling pain may suggest lumbar disc disease. A pain that comes and goes, reaching a peak and then quieting for a minute or two, only to reach a peak again, may suggest an altogether different cause of back pain, such as a kidney stone.

Age and gender help in diagnosing back pain. In a young patient, a benign tumor of the spine called an osteoid osteoma may be the culprit. Inflammatory bowel disease in young people can be connected with spondylitis (inflammation in the spinal joints) and sacro-iliitis (inflammation in the sacroiliac joint where the spine meets the pelvis).

Low back pain from disc disease or spinal degeneration is more likely to occur as people get older. Conditions such as abdominal aneurysm (a widening of the large artery in the belly) or multiple myeloma (a tumor that can attack bone) are also considered in older individuals. Osteoporosis and fibromyalgia are much more common triggers of back pain in women than in men. Osteoporosis is a progressive decrease in bone density that leaves the bones brittle, porous and prone to fracture. Fibromyalgia is a chronic disorder that causes widespread musculoskeletal pain, fatigue, and multiple “tender points” in the neck, spine, shoulders, and hips.

During the physical exam, the doctor may ask the patient to move in certain ways to determine the area affected. For example, the patient may be asked to hyperextend her back, bending backwards for 20 to 30 seconds, to see if that movement causes pain. If it does, spinal stenosis, a narrowing of the canal that runs through the vertebrae and houses the spinal nerves, may be the cause.

When tumor or infection are suspected, the doctor may order blood tests, including a CBC (complete blood count) and sedimentation rate (an elevated sedimentation rate indicates inflammation).

The Agency for Health Care Policy and Research established guidelines for acute low back pain in 1994. The federal agency suggests there are 8 red flags in low back pain that indicate the need for an x-ray:

These red flags identify patients who are more likely to get infection, cancer or who have a fracture, i.e., the patients are less likely to have a simple muscle strain. (Litigation compensation was included because Worker’s Compensation cases generally require x-ray.) If none of these red flags exists, an x-ray and other studies may be delayed for one month, during which time 90% of patients with acute back pain will feel better.

IV. Mechanical Low Back Pain

Because it represents 97% of cases, mechanical low back pain deserves to be discussed first. To determine the factors that bring out the pain, the doctor will consider the following causes of mechanical low back pain:

  • Muscle strain
  • Spondylolisthesis (slippage of one vertebral body on the next)
  • Herniated disc (the discs, or pads, that act as shock absorbers between the vertebrae can bulge into the space containing the spinal cord or a nerve root and cause pain)
  • Osteoarthritis (a common form of arthritis in which the cartilage that cushions the joints breaks down and bony spurs form in the joint, causing pain and swelling.)
  • Spinal stenosis (caused by a narrowing of the bony canal and predisposes some people to pain related to pressure on the spinal nerves or the spinal cord itself.)

Low back pain that gets worse with sitting may indicate a herniated lumbar disc (one of the discs in the lower part of the back). Acute onset, that is, pain that comes on suddenly, may suggest a herniated disc or a muscle strain, as opposed to a more gradual onset of pain, which fits with osteoarthritis, spinal stenosis, or spondylolisthesis.

V. Inflammatory Low Back Pain

Although comparatively few patients have low back pain due to inflammation, the problem can be life long and can impair function significantly. The good news is that treatments can help essentially all patients, and can lead to major improvements.

Seronegative spondyloarthropathies are a group of inflammatory diseases that begin at a young age, with gradual onset. Like other inflammatory joint diseases, they are associated with morning stiffness that gets better with exercise. Sometimes fusion of vertebrae in the cervical or lumbar regions of the spine occurs. Drugs called TNF-alpha blocking agents, (such as etanercept, infliximab and adalimumab) which are used for rheumatoid arthritis, are also used to treat the stiffness, pain, and swelling of spondyloarthropathy, when the cases are severe and not responsive to traditional medications.

People who have spondyloarthropathy have stiffness that is generally worst in the morning, and have decreased motion of the spine. They also can have decreased ability to take a deep breath due to loss of motion of the chest wall. It’s important for the physician to look for problems with chest wall expansion in patients with spondyloarthropathy.

Treatment for inflammatory back pain includes stretching and strengthening exercises. If there is chest wall involvement, chest physiotherapy is important. Avoiding pillows under the neck when sleeping can help the cervical spine - if it fuses - to fuse in a less debilitating position. Non-steroidal anti-inflammatory agents are useful. In patients with more severe disease, the drugs used are typically sulfasalazine and methotrexate. If the patient is not doing well despite trying these medications, TNF-alpha blockers, appear to provide benefit in such spondyloarthropathies as ankylosing spondylitis and psoriatic arthritis. Etanercept (Enbrel®), adalimumab (Humira®), infliximab (Remicade®) and Golimumab (Simponi®) are anti-TNF agents presently approved by the FDA for use in this condition. The fifth presently-available anti-TNF agent, certolizumab (Cimzia®) has not as yet received FDA approval for ankylosing spondylitis. These agents clearly improve the patient’s ability to move and function. More study is needed to see whether these medications can prevent fusion of the spine, over the long run.

Reactive arthritis syndrome is one of the forms of spondyloarthropathy. It is a form of arthritis that occurs in reaction to an infection somewhere in the body, and it carries its own set of signs and symptoms. The doctor will look for skin rashes, gastrointestinal or urinary problems, eye inflammation, mouth sores, and involvement of joints of the arms or legs, in addition to back pain. Reactive arthritis is treated similarly to ankylosing spondylitis and psoriatic arthritis, with sulfasalazine and methotrexate, and, if necessary, TNF-alpha blockers. If there is any clue to infection at the time the arthritis starts, such as infectious diarrhea or infection of the genitourinary tract, these conditions will be treated. However, even with treating the underlying infection, reactive arthritis can continue. This is because reactive arthritis is an inflammatory reaction to an infection, and the inflammation can continue after the infection is gone.

VI. Low Back Pain Caused by Infection

Infections of the spine are not common, but they do occur. The doctor will ask about the usual signs and symptoms of infection, especially when back pain is accompanied by fever and/or chills. Dialysis patients, IV drug users, and patients who have recently had surgery, trauma, or skin infections are at risk for infections of the spine. Infections of the spine can be caused by a number of agents, most commonly bacteria. Doctors will first test for the presence of bacteria, then give antibiotics.

VII. Fractures and Low Back Pain

Fractures of the spine are often very difficult pain problems and indicate the possible presence of osteoporosis (a bone disease marked by a progressive loss of bone density and strength, making the bones brittle and vulnerable to breaking). In patients with severe osteoporosis, spinal fractures can occur with no early warning and no significant trauma—the patient does not have to fall to fracture a vertebrae.

Patients with spinal compression fractures experience spasms and very high pain levels.

In patients with low back pain where the cause is difficult to determine, especially for elderly patients with osteoporosis, a fracture in the sacrum (the bone between the two hip bones) may be the cause of the pain. A standard x-ray or bone scan may not show a sacral fracture. Imaging techniques such as CT scan (Computer Tomography, a type of x-ray examination that obtains digital images of the body using a thin x-ray beam) or MRI (magnetic resonance imaging, a diagnostic test that depicts both soft tissue and bone) can often reveal these fractures.

It is very important that patients with acute lumbar compression fractures be tested for osteoporosis. A bone density study is needed, unless the patient has no other osteoporosis risk factors and has had a very high impact fracture. Studies have shown that many patients with fractures in the U.S. are discharged from hospitals with no plans for management of their bone density problems, which then are left to worsen.

If osteoporosis is found, many treatments are available, including calcium, vitamin D, and a number of prescription drugs. The variety of agents available to treat osteoporosis is large enough that an agent can generally found for each patient, even if other medical problems make one or another of the agents wrong for them. In patients who have just had a spinal fracture, and their bone density is not yet known, nasal calcitonin is a medication that has been shown to reduce fracture pain (and which has some benefit for bone density). Once bone density is measured, a decision as to long term osteoporosis management can be made.

Although pain can be very intense, it is best for patients with lumbar fracture to resume activity as soon as possible. This is especially true for elderly patients, who can too easily become weakened, and develop other complications, if mobility is reduced for too long. Opioids (synthetic narcotic drugs that are not the same as opium) are often needed for pain control, for a brief period.

If patients have multiple spinal compression fractures, or if they have post-fracture pain that does not respond to treatment, procedures such as vertebroplasty (done as an outpatient) and kyphoplasty (done in the operating room), have been used. Vertebroplasty is an outpatient procedure that uses three-dimensional imaging to help the doctor guide a fine needle into the vertebral body. Cement is injected, which quickly hardens to stabilize and strengthen the bone and provide pain relief (although it does not restore height to the bone). In kyphoplasty, which is done in the operating room, prior to injecting the cement, a special balloon is inserted and inflated to restore height to the bone and reduce spinal deformity. These procedures have become more controversial in the literature in 2009, and patients should discuss the pros and cons of these procedures in detail with their physicians if they are proposed for their particular situation.

In patients with acute spinal fracture, options used for management include: 1) returning to activity as soon as possible. 2) pain management, e.g., with opioid medication, at times with epidural steroid injection. 3) Nasal calcitonin has been reported to decrease pain of spinal compression fracture. 4) Vertebroplasty and kyphoplasty have been used (see discussion above). 5) Do a bone density study to see if the patient has osteoporosis, so that this can be treated, and also evaluate for any other possible cause of spinal fracture, such as bone tumor.

VIII. Low Back Pain and Cancer

Cancer involving the lumbar spine (low back) is rare. However, in people who have a prior history of cancer, for example, in the breast or prostate, or who have weight loss or loss of appetite along with back pain cancer needs to be considered.

Night pain can be a clue to cancer in the spine. A benign tumor called osteoid osteoma, which most often affects young people, causes pain that tends to respond well to aspirin. Multiple myeloma is a malignancy that occurs when the plasma cells in the bone marrow begin reproducing uncontrollably. It is most common in older people, and can cause pain in many parts of the spine. When tumor or infection are suspected, blood tests may be ordered, including a CBC (complete blood count especially to detect anemia), sedimentation rate (an elevated sedimentation rate indicates inflammation, tumor or infection), and protein electrophoresis (which is a screening test for myeloma).

IX. Referred Pain to the Lumbar Spine

Pain in the area of the lumbar spine may be due to important problems that are actually unrelated to the back. Referred pain occurs when a problem in one place in the body causes pain in another place. The pain travels down a nerve. For example, a pinched nerve in the neck may cause pain that is felt in the arm or hand. Actual sources of referred pain could include abdominal aneurysm (enlarged artery in the belly), tubal pregnancy, kidney stones, pancreatitis, and colon cancer. Clues to these maladies include pain that waxes and wanes over a short period, with frequent peaks of intense pain, weight loss, abnormalities found during abdominal exam, and trace amounts of blood in the urine.

X. Chronic Low Back Pain

When back pain continues for more than 3 months, it is considered chronic. It often progresses and can have a major impact on one’s ability to function. For some patients, physical therapy with local heat or ice application (10-15 minutes on and 10 minutes off), combined with a home exercise program and education in lifting and other movement techniques can make a major difference. Patients must learn to tolerate a certain degree of pain, or they may allow themselves to become more disabled than necessary. Patients at the Hospital for Special Surgery have had success with “graded exercise” to work through the pain, gradually increasing the exercise quota at each session so they can learn to tolerate more exercise in spite of the pain, and get back to work and activities. More details are provided in the article The Goals of Physical Therapy for Low Back Pain.

XI. When Are Certain Diagnostic Tests Necessary?

A. Imaging: X-ray, MRI and CT Scan

There is concern within the medical community that high-tech imaging methods, such as CT scan and MRI, are overused for acute low back pain. Often, these sensitive imaging techniques reveal abnormalities in the lumbar spine that are not the cause of the patient’s pain. In one study, volunteers with no history of back pain were given MRIs and 90% of those over age 60 had degenerative disc disease. MRIs that show abnormalities in the lumbar region that cause no symptoms for the patient are not helpful.

The presence of red flags for infection, fracture, or more serious disease will likely require an MRI or CT scan. Also, if symptoms last longer than a month and surgery is being considered, imaging is necessary. When a patient has had prior back surgery, imaging beyond x-ray is reasonable.

If a patient has signs of cauda equina syndrome, a serious injury to the spinal cord, causing symptoms such as leg weakness, perineal numbness (numbness between the inner thighs) and difficulty urinating), permanent neurological damage may result if this syndrome is left untreated. If clues to this syndrome are present, an MRI, or at minimum, a CT scan, is urgently needed.

B. Blood Tests

When tumor or infection are suspected, blood tests may be ordered, including a CBC (complete blood count especially looking for anemia) and sedimentation rate (an elevated sedimentation rate indicates inflammation).

XII. Treatment Options for Acute Low Back Pain

Most low back pain can be treated without surgery. To treat the pain, medications such as acetaminophen (Tylenol), non-steroidal anti-inflammatory agents (such as aspirin, naproxen, and ibuprofen), and opioids can be used. NSAIDs suppress inflammation, pain and fever by inhibiting certain inflammation-causing chemicals in the body. Acetaminophen reduces pain and fever, but does not inhibit inflammation. Opioids (such as codeine) provide pain relief only and are often prescribed to manage severe acute and chronic back pain. Epidural injection is an option if the back pain does not respond to these treatments. Each person is different in terms of response to medication.

In contrast with popular wisdom, numerous studies have shown that bed rest beyond 2 to 3 days is not helpful. Patients should resume activities as soon as possible. Exercise is an effective way to speed recovery and help strengthen the back and abdominal muscles. Exercise also helps reduce the risk that the back pain will return. Doctors or physical therapists should provide a list of exercises to do at home. It is also important to learn lifting techniques and exercises to reduce work-site injuries. Lumbar corsets are only appropriate if helpful in the work setting. Routine use of lumbar corsets may weaken spinal muscles and delay recovery. Spinal manipulation can be effective for some patients with acute low back pain.

Other techniques:

  • IntraDiscal Electrothermal Therapy (IDET) uses thermal energy to treat pain resulting from a cracked or bulging spinal disc. A special needle is inserted via a catheter into the disc and heated to a high temperature for up to 20 minutes. The heat thickens and seals the disc wall and reduces inner disc bulge and irritation of the spinal nerve.
  • Nucleoplasty uses radiofrequency energy to treat patients with low back pain from contained, or mildly herniated, discs. Guided by x-ray imaging, a wand-like instrument is inserted through a needle into the disc to create a channel that allows inner disc material to be removed. The wand then heats and shrinks the tissue, sealing the disc wall. Several channels are made depending on how much disc material needs to be removed.
  • Radiofrequency lesioning is a procedure using electrical impulses to interrupt nerve conduction (including the conduction of pain signals) for 6 to12 months. Using x-ray guidance, a special needle is inserted into nerve tissue in the affected area. Tissue surrounding the needle tip is heated for 90-120 seconds, resulting in localized destruction of the nerves.

XIII. Surgery for Low Back Pain

Because the vast majority of patients recover from their low back pain with little help from a doctor, the rationale behind choosing surgery must be convincing. Eighty percent of patients with sciatica recover eventually without surgery.

Severe progressive nerve problems, bowel or bladder dysfunction and the cauda equina syndrome (described above) make up the most clear-cut indications for back surgery. Back surgery will also be considered if the patient’s signs and symptoms correlate well with studies such as MRI and electromyogram (a diagnostic procedure to assess the electrical activity in a nerve that can detect if muscle weakness results from injury or a problem with the nerves that control that muscle).

Types of Surgery [2]

In the most serious cases, when the condition does not respond to other therapies, surgery may relieve pain caused by back problems or serious musculoskeletal injuries. Some surgical procedures may be performed in a doctor’s office under local anesthesia, while others require hospitalization. It may be months following surgery before the patient is fully healed, and he or she may suffer permanent loss of flexibility. Since invasive back surgery is not always successful, patients should consider it only when they have progressive neurologic disease, or when they are very severely disabled by pain.

  • Discectomy is one of the more common ways to remove pressure on a nerve root from a bulging disc or bone spur. During the procedure the surgeon takes out a small piece of the lamina (the arched bony roof of the spinal canal) to remove the obstruction below.
  • Foraminotomy is an operation that “cleans out” or enlarges the bony hole (foramen) where a nerve root exits the spinal canal. Bulging discs or joints thickened with age can cause narrowing of the space through which the spinal nerve exits and can press on the nerve, resulting in pain, numbness, and weakness in an arm or leg. Small pieces of bone over the nerve are removed through a small slit, allowing the surgeon to cut away the blockage and relieve the pressure on the nerve.
  • Spinal fusion is used to strengthen the spine and prevent painful movements. The spinal disc(s) between two or more vertebrae is removed and the adjacent vertebrae are “fused” by bone grafts and/or metal devices secured by screws. Spinal fusion may result in some loss of flexibility in the spine and requires a long recovery period to allow the bone grafts to grow and fuse the vertebrae together.
  • Spinal laminectomy (also known as spinal decompression) involves the removal of the lamina (usually both sides) to increase the size of the spinal canal and relieve pressure on the spinal cord and nerve roots.

Other surgical procedures to relieve severe chronic pain include rhizotomy, in which the nerve root close to where it enters the spinal cord is cut to block nerve transmission and all senses from the area of the body experiencing pain; cordotomy, where bundles of nerve fibers on one or both sides of the spinal cord are intentionally severed to stop the transmission of pain signals to the brain; and dorsal root entry zone operation, or DREZ, in which spinal neurons transmitting the patient’s pain are destroyed surgically. The multiplicity of possible surgical options requires that patients fully discuss the options in their individual case with their spinal surgeon.

XIV. Summary

97% of back pain will have a mechanical cause and most will get better quickly. The other potential causes will need to be considered early on, because many of these other types of back pain require very specific approaches to non-surgical or surgical therapy. Many patients do not need x-rays, and many more do not need CT or MRI scan, which are overly sensitive and often reveal abnormalities not related to the patient’s pain. Careful, early attention to obtain the correct diagnosis will maximize the success of the treatment chosen for the individual patient. When back pain is associated with fever, loss of leg sensation or strength or difficulty with urination, quick medical attention is required. Where back pain is mechanical, patients can exercise and learn lifting and movement techniques for prevention of future episodes.

XV. Useful Links and References

Low Back Pain Fact Sheet, National Institute of Neurological Disorders and Stroke, National Institutes of Health. Reviewed, July 26, 2003
www.ninds.nih.gov/health_and_medical/pubs/back_pain.htm

Special Report: The Goals of Physical Therapy for Low Back Pain, Hospital for Special Surgery, Theodore R. Fields, MD, FACP, February 11, 2004.

Deyo RA, Weinstein JN, Low Back Pain, N Engl J Med, Vol 344, No. 5, Feb 1, 2001, pp 363-370.

1, 2. Excerpted from Low Back Pain Fact Sheet, National Institute of Neurological Disorders and Stroke, National Institutes of Health

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