Your spine is a column of small bones called vertebrae, which supports the entire upper body. A letter and number are used to designate each small bone. The letter shows the region of the spine: C=cervical (neck), T=thoracic (chest), and L=lumbar (lower back). The number notes its location within that region. For example, C4 is the fourth bone down in the neck region. There are seven cervical, twelve thoracic and five lumbar vertebrae.
Most of the body’s weight and stress falls on the lower back area. Below the lumbar region is the sacrum, a shield-shaped bony structure that connects with the pelvic bone. At the end of the sacrum are two to four tiny, partially joined bones known as the coccyx or ‘tail bone.’
Small cushions of cartilage, known as intervertebral discs, separate the bones in the back from each other. A disc is 80 per cent water, which makes it very elastic. It has no blood supply of its own, but relies on nearby blood vessels to keep it nourished. Inside each disc is a jelly-like substance that is surrounded by a fibrous structure.
Each bone in the back has a number of bony parts that stick out, known as processes. They attach to the muscles in the back and act like little levers, allowing the spine to twist or bend. Each bone and its processes surround and protect an arch-shaped middle opening. Together, all these vertebrae form a canal that runs down the back and encloses the spinal cord.
The spinal cord is the central trunk of nerves connecting the brain with the rest of the body. Nerves pass from the spinal column to other parts of the body. When the spinal cord reaches the lumbar region, it splits into four bundled strands of nerve roots called the cauda equina, (which means horsetail in Latin).
Various problems that may occur along the ridge of bone and disc often result in stretched or pinched nerves which can trigger low back pain. The causes of these problems include: injuries and small fractures; increased pressure on a weakened disc causing it to rupture (disc herniation); spinal stenosis (a narrowing of the spinal canal); misalignment or inflammation of the facet joints (one of the vertebral connection points); and muscle spasm.
In 85 per cent of low back pain cases, the causes are unknown. In most cases where the cause is known, the pain begins with an injury after lifting a heavy object, or after making an abrupt movement.
A number of conditions may make people more or less likely to experience low back pain.
The sciatic nerve which supplies the leg is the nerve most likely to be affected in low back pain. The pain resulting from irritation to it is known as sciatica. About 40 per cent of people will experience this pain. A herniated disc pressing on the sciatic nerve is the most common cause. It can also occur from spinal stenosis or other abnormalities of the vertebrae.
The sensation of sciatica ranges from mild tingling to pain severe enough to cause immobility. It most often occurs on one side. Some people experience sharp pain in one part of the leg or hip and numbness in other parts. The pain increases after standing or sitting for long periods. Sneezing, coughing, or laughing can all make it worse.
People in jobs that involve lifting and forceful movements, bending and twisting into awkward positions, and whole-body vibration (such as long-distance truck driving) have a higher chance of developing low back pain. People who do not exercise regularly are more likely to have low back pain, especially during times when they suddenly do an unaccustomed activity, such as shoveling, digging, or moving heavy items. A common cause of temporary low back pain in children is carrying backpacks that are too heavy. Smokers are more likely to have back problems, perhaps because smoking decreases blood circulation.
Certain warning signs should alert a person to see a doctor immediately for low back pain. Severe back pain always warrants attention, particularly if any of the following conditions are present.
An X-ray can help to rule out infection, injuries, or tumors. It may also reveal signs of narrowing and changes in the spine due to aging. A Computed Axial Tomography (CAT) or Magnetic Resonance Imaging (MRI) scan are more helpful in determining the cause of low back pain.
New low back pain can be treated with an over-the-counter pain reliever and lying down in a comfortable position. Alternating ice packs with a heating pad is helpful in relieving the pain. Ice packs should be applied first. Changing from hot to cold every three minutes and repeating this sequence three times a day is sometimes recommended. Heat or cold treatments do not have much effect on sciatica.
Supportive back belts, braces, or corsets may help some people temporarily. Since they can reduce muscle tone over time they should be used only briefly. Bed rest for more than a few days is no longer recommended. In fact, bed rest for low back pain is no more effective and may even be worse than simply continuing normal activities to the degree possible. This advice includes most cases of sciatica. Long-term bed rest results in loss of muscle tone and bone strength, increases the chance of blood clots, and can cause depression and lethargy.
Although bed rest is no longer recommended, healthy sleep plays a vital role in recovery. It is often difficult to get a good night’s sleep when suffering from back pain, particularly because pain can become worse at night. Lying curled up on the side (in a fetal position) with a pillow between the knees or lying on the back with a pillow under the knees may help. To help promote sleep, avoid caffeine in the afternoon and evening, take a warm bath before bedtime, and practice relaxation techniques. It may be necessary to take medication to help manage pain at night or treat sleeplessness.
Experts now recommend that people with acute low back pain try to resume normal activities as soon as possible. This should be done without strain or stretching. Simply letting pain be the guide is the best approach for achieving movement. In general, normal activity should be resumed gradually as soon as the person feels ready. Asking your family doctor for a referral to a physiotherapist for a program of core strengthening exercises can also help you to manage existing back pain and prevent future recurrence.