What causes low back pain?
For most persons with low back pain, no specific cause is ever found. It is estimated that a clear explanation can be identified in only about 10 percent to 15 percent of cases. Among the common causes, however, are the following:
- Muscle or ligament strain — Some of the largest, hardest-working muscles in the body are in or near the lower back. Unlike muscles stressed primarily during exercise, these muscles are also stressed with sitting, standing and walking.
- Degenerative joint disease — The joints that allow mobility and stability are subject to wear and tear. In degenerative joint disease (also called osteoarthritis), the shiny, smooth cartilage that lines the joint wears away, leaving bone to rub on bone, a painful situation.
- Disk disease — Given their location, torn or bulging disks can readily compress the spinal cord or nerves traveling out of the back.
- Spinal stenosis — Narrowing (stenosis) of the spinal canal can be caused by calcium deposits in ligaments, degenerative joint disease or disk disease, or it may be present since birth. Any of these problems alone or in combination can lead to pressure on the spinal cord or a nearby nerve, causing pain.
- Spondylolisthesis — Spondylolisthesis is a relatively common condition, especially among older persons, in which one vertebra slides forward on another. When a tiny defect or fracture in the bones at the back of the vertebrae is also present, the condition is called spondylolysis. In either case, the spinal cord or nerves leaving the cord can be compressed, causing pain in the back or legs.
- Osteoporosis with compression fracture — By itself, osteoporosis is painless, but it increases the risk of bone fracture, especially fractures of the hip, wrist and vertebrae. The fracture itself or the resulting abnormal curvature of the spine or pressure on nerves may be a source of pain.
Why is low back pain so common?
The reason the lower back is so prone to trouble is not entirely clear but probably relates to the remarkable stresses placed on it over a lifetime. And although the lower back may seem simple enough (especially when it isn’t causing any trouble), it has a complex anatomy that allows it to serve several basic functions:
- To protect the spinal cord
- To allow mobility of the lower back
- To provide support for the rest of the spine, allowing upright posture
- To allow attachment of many muscles, including those involved in hip motion that allow sitting, standing and walking
Is low back pain ever life threatening?
People with back pain, especially back pain that is severe or long lasting, often wonder if the cause is life threatening. Fortunately, life-threatening causes are rare, representing less than 1 percent of all cases of back pain. Of these rare causes, infection and cancer top the list. In most cases, recognizing risk factors and associated features readily identifies these causes.
Health-care providers will ask whether you have noticed other problems along with the back pain. Important “red flag” symptoms that could indicate a life-threatening condition include significant trauma, weight loss, fever, pain that spreads into one or both legs, numbness, tingling or weakness in one or both legs, or bowel or bladder incontinence.
More specifically, cancer is often associated with weight loss, poor appetite, a history of cancer elsewhere in the body, pain that worsens at night and constant but progressively worsening pain. Back pain caused by cancer may cause bowel or bladder incontinence or leg weakness and is more common in older persons. Infection may be associated with fever and weight loss and usually follows some risk factor, such as intravenous drug use, a prior medical condition, use of drugs that suppress the immune system (such as those used to prevent rejection of an organ transplant), long-standing diabetes, cirrhosis, HIV or a recent injury or surgery.
What tests are used to evaluate low back pain?
Because most people with low back pain return to a normal state of health within a month (often much sooner), there is usually no need for testing. However, diagnostic tests are appropriate when a life-threatening cause is suspected; when pain does not improve with the usual, conservative measures; or when surgical treatment is being considered.
Keep in mind that no test is perfect. The tests may find abnormalities that have nothing to do with low back pain, or they may detect normal findings in persons with severe back pain. Thus, care must be taken regarding which tests are ordered and how the results are interpreted. Testing is particularly helpful when a life-threatening cause of pain is suspected (because early diagnosis is important) and when test results are likely to have a significant effect on treatment and outcome.
How is low back pain treated?
Low back pain can be treated in a number of ways. To some extent, the best treatment depends on the cause. Many common causes are treated similarly, but rarer, life-threatening causes require more specific treatment.
Conservative treatment is usually tried first. Conservative treatment may include physical therapy, stretching and massage.
Acetaminophen, anti-inflammatory drugs (such as naproxen or ibuprofen) or a muscle relaxant may be helpful. Rest is recommended only as required by the severity of pain; activity, if tolerated, is encouraged. If a life-threatening cause of pain is not suspected, you can consider alternative and complementary therapies, including acupuncture, chiropractic care or homeopathy.
Any life-threatening cause needs to be directly addressed. For example, a bacterial cause should be treated with antibiotics, and a cancerous cause typically requires chemotherapy, radiation and/or surgery. Whatever treatment is chosen, re-evaluation may be important to be sure the diagnosis is correct and to re-assess other treatment options. Referral to a specialist (including an orthopedist, rheumatologist, neurosurgeon or pain expert) may be a good idea.
If pain continues, stronger pain medications and injections with anesthetic and corticosteroid agents may be appropriate. Sometimes, electrical stimulation of the area is helpful. If a surgically treatable cause of pain is discovered, surgery, as a last resort, may be required for relief of symptoms.
Is surgery ever necessary to treat low back pain?
For certain conditions (such as disk disease, spinal stenosis, spondylolisthesis or spondylolysis), surgery may prove to be the only highly effective treatment, although it is usually used as a last resort. Surgery does not work well for all causes of low back pain, and it is usually appropriate for only those situations in which a definite anatomic abnormality is causing the pain. When no identifiable cause of back pain is present, surgical intervention should rarely, if ever, be considered.
Surgical options include minimally invasive procedures. These procedures use small incisions and require less recovery time than does traditional (open) surgery. Minimally invasive surgery may be used to treat certain types of fractures or disk disease.
The best way to decide about surgery is to discuss this treatment option with your primary care physician and your surgeon. It may be helpful and reassuring to get an independent, second opinion before scheduling an operation. Unless you have a life-threatening condition for which urgent surgery is clearly necessary, the decision to have surgery requires that you and your doctors compare the risks and benefits of surgery with the risks and benefits of nonsurgical options. Only you can assess the amount of pain you have and its effect on your quality of life and function. For every case, the decision to undergo surgery must be individualized.
How can low back pain be prevented?
Because not everything about low back pain is understood, it is not always possible to prevent a recurrence. However, there are some general recommendations that you can follow to reduce your risk. Remember that it is usually best to avoid doing too much too soon. So start slowly.
If you are prone to back pain, it is also important that you work closely with your health-care provider. He or she can help keep you on track and remain pain-free.