Incidence of Low Back Pain

Back problems are among the most expensive of musculoskeletal disorders in industrialized nations, and one of the most common work related ailments affecting adults in the United States. In any given year, 50 percent of the working population will experience back pain, with 80 percent reporting low back pain (LBP) at some time during their lifetime. Although the vast majority of individuals suffering from back pain will fully recover within one month (90 percent), low back pain may also be a cause of chronic pain and long term disability.

As might be expected, fire fighters are at increased risk of back injury compared to other professions secondary to rigorous physical requirements of the occupation. The International Association of Fire Fighters’ annual Death and Injury Survey reveals that sprains and strains routinely account for approximately 50 percent of all line-of-duty injuries and back injuries account for approximately 50 percent of all line-of-duty injury retirements each year. These injuries may result in significant lost time and medical expense.

This article will discuss the anatomy of the lower back, common causes of LBP, measures for preventing LBP, and treatment of minor LBP. Given the fact, however, that back pain has a number of causes with more severe implications, it is recommended that LBP always be treated in consultation with a health care provider.

Anatomy of the Lower Back

The “lower back” is most commonly described as the area from the thorax to the pelvis on the dorsal (back) aspect of the body, containing a number of anatomic structures which should be understood if a thorough understanding of back pain is to be gained. These anatomic structures include the lower back musculature, lower back ligaments, lumbar vertebrae, vertebral discs, the spinal cord, spinal nerves, and several joints as shown below.

Lumbar vertebrae – The spine itself is made up of 33 vertebrae (bony segments stacked on top of each other connecting the upper spine to the pelvis) arranged in 5 sections (cervical, thoracic, lumbar, sacral, and coccygeal). The lumbar segment contains 5 vertebrae and is the origin of most back pain. A complex system of ligaments, cartilage, and muscle maintains these vertebrae in proper position. Working together, this system’s components provide enormous strength and flexibility, helping to support your weight and maintain your upright position while resisting the jarring physical rigors of daily life.

Small joints – Each vertebrae consists of a thick cylindrical hollow-core bone from which three bony pieces jut out, one to each side and one toward the rear. The bony prominences join with those of the adjacent vertebrae at a joint called a facet. When thrown out of alignment, the facet presses on nerve tissue and causes pain. When the vertebrae are aligned, their centers form a canal through which the spinal cord passes; spinal nerves, connecting the cord to the body’s network of nerves, pass through openings between each vertebra. Vertebral fractures or pressure from protruding disks at the point where nerves pass through spinal openings can impinge or “pinch” the nerves, causing damage and pain.

Lower back muscles and ligaments – Muscles and ligaments connect vertebrae and provide strength and stability while at the same time allowing flexibility. Strains (muscle) or sprains (ligaments) of these structures are a common source of low back pain.

Vertebral discs – Acting as cushioning shock absorbers/stabilizers, the lower back contains 6 vertebral discs which protect the lumbar vertebrae. The vertebral disk is composed of the nucleus pulposis, a soft jelly-like center or nucleus, and the fibrous annularis, a tough outer portion surrounding the nucleus. Discs may degenerate under stress or as a result of the normal aging process.

Spinal cord and nerves – The spinal cord runs through a central canal in the lumbar vertebrae, allowing transmission of electrical signals from the brain to the muscles of the legs. Spinal nerves leave the spinal cord between each set of vertebral bodies with compression/impingement potentially resulting in pain, numbness, or loss of function.

Common Causes of Low Back Pain

The following paragraphs will describe several common causes of LBP. Although most sources of LBP resolve spontaneously and may be self-treated, a number of causes are more serious medical conditions with serious consequences. It is therefore recommended that back pain be treated in consultation with a physician.

Lumbosacral sprain and strain – As shown above, the lower back contains numerous muscles and ligaments allowing strength and stability for walking, lifting, standing, bending, etc. A strain is an injury to the lower back musculature, usually caused when a muscle is overworked, overstretched, or used in a poorly conditioned state. Pain most commonly occurs during or immediately following activity, and is usually worsened with back flexion/standing and relieved with rest. Muscle spasm (involuntary contraction) is a common response to injury as the body attempts to immobilize the painful area and prevent further damage.

A sprain is an injury to the ligaments of the lower back. These injuries commonly occur when a sudden or forceful movement injures a ligament which has become stiff or weak due to lack of conditioning or overuse. Lumbosacral sprains and strains are the most common causes of low back pain, and are frequently caused by a number of factors including poor conditioning, improper biomechanics/lifting, obesity, and smoking. Although the aging process cannot be completely halted they can be slowed by regular exercise, proper lifting techniques, proper nutrition, and avoidance of smoking.

We will next discuss degenerative sources of LBP. Normal “wear and tear” and several inherited factors may cause degenerative changes in several areas in the lower back.

Degenerative Disc Disease/Disc Herniation – When degenerative changes occur in the disks, the process is often referred to as degenerative disk disease. Between vertebral bodies, vertebral disks act as shock absorbers, cushioning the lower back from loads and stressors of daily work. The vertebral disk is composed of the nucleus pulposis, a soft jelly-like center or nucleus, and the fibrous annularis, a tough outer portion surrounding the nucleus. With aging, the nucleus begins to harden and occasionally cracks/weakens and material from the disk may push out or rupture. Bulging of disks is common and often painless. The herniation becomes painful when excessive bulging or fragments of the disc herniate and place pressure on nearby nerves, often referred to as a herniated or slipped disk.

Osteoarthritis – Degenerative changes may also occur in the small joints between vertebral bodies. These changes occur to some degree in everyone, but are especially common in those over the age of 60. Overload, injury, and aging may slowly cause deterioration of the cartilage between vertebral joints. Disc narrowing, joint inflammation, and bone spur formation may occur potentially resulting in low back stiffness, pain, and nerve irritation/leg pain. These effects may be seen below.

Sciatica – Disc herniation, osteoarthritis, and other causes of LBP may cause inflammation or compression of nerves in the lower back with resulting pain in the lower leg known as “sciatica”. Compression or inflammation of the nerve roots in your spine that form the sciatic nerve cause pain in the buttock or leg as seen below. As this symptom may be caused by a number of processes including fracture, cancer, infection, and vertebral body slippage, patients with sciatica should be seen by their physician.

Osteoporosis – Most commonly seen in patients older than 50, especially women, osteoporosis is defined as a thinning of bone mass. This condition results in porous and brittle vertebral bodies, which are weaker than normal vertebrae predisposing the patient to vertebral compression fractures. Management of osteoporosis with your doctor and smoking cessation may reduce your risk of these fractures.

Spinal Stenosis – Spinal stenosis is defined as soft tissue and/or bony encroachment on the spinal cord and/or nerve roots often resulting in leg pain, numbness, or weakness. Spinal stenosis commonly occurs in middle age to older adults and is worsened by walking and relieved by sitting. Your provider may order imaging studies to confirm this diagnosis.
Personal Risk Factors

Studies have linked incidence of low back pain to smoking and being overweight. Therefore stopping smoking and maintaining an ideal body weight may decrease the incidence and duration of back pain.

Click here for the US Fire Administration manual on Ergonomics

Prevention of Low Back Pain

The effects of aging that result in decreased bone mass, decreased strength and elasticity of muscles and ligaments can’t be halted completely, but may be slowed. With a little care and attention, you may be able to avoid an aching back in the first place. Speak with your health care provider to find out what you can do to reduce your likelihood of developing LBP.

Exercise – Regular aerobic activities that don’t strain or jolt your back can increase strength and endurance in your lower back, allowing your muscles to function more effectively, and allowing you to maintain an appropriate body weight, eliminating unnecessary strain on your back muscles. These aerobic exercises may include walking, swimming or biking. Talk with your doctor about which activity is best for you. Conditioned abdominal and back muscles work to protect and stabilize your back. Flexibility in your hips and upper legs allows for proper pelvic bone alignment, which improves how your back feels. Performing simple exercises on a regular basis can help support and align your back.

Proper Biomechanics – additionally, the following activities will reduce stress on the lower back during everyday activities.

Stand smart – Maintain a neutral pelvic position. If you must stand for long periods of time, alternate placing your feet on a low footstool to take some of the load off your lower back.

Sit smart – Choose a seat with good lower back support or place a pillow or rolled towel in the small of your back to maintain its normal curve. Keep your knees and hips level.

Lift smart – Let your legs do the work. Move straight up and down. Keep your back straight and bend only at the knees. Hold the load close to your body. Avoid lifting and twisting simultaneously.

Sleep smart – Lie on a firm mattress. Use pillows for support, but don’t use a pillow that forces your neck up at a severe angle.

Avoid Smoking

Treatment of Low Back Pain

Self Care – Because most back problems aren’t life threatening, many doctors recommend home treatment first. Regardless of the type of treatment, most people find that their back pain gets better within 6 weeks. If you have strained ligaments or severe muscle strain, your recovery could take as long as 12 weeks.

A sore back often settles down or improves within a short period of time. Rest for only 1 or 2 days if your back pain is severe, because prolonged bed rest can reduce your muscle strength and lead to further disability. These steps can help you treat back pain at home:

Apply cold, then heat. Sources of heat and cold, including a hot bath and hot or cold compresses, can soothe sore and inflamed muscles. Use cold treatment first. Immediately after injuring your back, apply ice several times a day, for up to 20 minutes at a time. Put the ice in a bag, then wrap the bag in a cloth or towel to keep a thin barrier between the ice and your skin. Use ice for as long as spasms persist. After spasms and acute pain subside, you can apply heat from a heating pad or heat lamp to help loosen tight muscles. Limit each heat application to 20 minutes.

Use pain relievers. Over-the-counter pain relievers such as acetaminophen (Tylenol, others) may help control pain. Nonsteroidal anti-inflammatory drugs such as aspirin and ibuprofen (Advil, Motrin, others) also can reduce inflammation.

When to Seek Medical Advice – Most back pain disappears with home treatment and self-care. Although it may take several weeks for complete resolution, if you don’t feel some improvement within the first 72 hours of self-care, or notice any of the signs/symptoms listed below, see your doctor.

  • LBP with a fever of 100.4 F or higher for more than 48 hours
  • Constant or intense LBP, especially at night
  • LBP spreading down one or both legs
  • LBP with weakness, numbness or tingling in one or both legs
  • LBP which interfere with bladder and bowel control
  • LBP associated with abdominal pain or pulsation (throbbing)
  • LBP following trauma (e.g. a fall or car crash)
  • LBP with a history of back pain, previous back surgery, or cancer
  • LBP lasting longer than 6 weeks
  • LBP when you are older than age 50
  • LBP if you have lost more than 10 pounds within 6 months

Screening and Diagnosis – Your doctor will examine your back to determine where the pain is, what degree of motion you have without pain, and whether you have muscle spasms. Your doctor may also order the following tests to help with diagnosis.

X-ray – These images show the alignment of your bones, whether you have degenerative joint disease and whether you have a tumor.

Myelography – A special dye injected into your spinal canal allows a herniated disk or other lesions to show up on X-rays.

Magnetic resonance imaging (MRI) or computerized tomography (CT) scans – These scans can generate images that may reveal herniated disks or problems with bones, muscles, cartilage, ligaments, tendons and blood vessels.

Bone scan – You’ll receive an injection of a radioactive substance (tracer) into a vein. Using a special camera, your doctor may be able to detect bone tumors or compression fractures caused by osteoporosis.

Electrodiagnostic studies – Studying your nerve conduction pathways can confirm nerve compression caused by herniated disks or narrowing of your spinal canal (spinal stenosis). Electrodiagnosis measures how long it takes for an electrical charge to move from a needle in your spine to a needle in your leg.

Treatments for back pain may include:

Medications – Prescription drugs such as nonsteroidal anti-inflammatory drugs (NSAIDS) and muscle relaxants may relieve mild to moderate back pain. Your doctor may also use corticosteroid injections to ease more severe back pain.

Heat, cold and massage – When performed by a licensed professional, applications of heat, cold and gentle massage may relieve back pain due to muscle spasms. A word of caution — manipulation of your spine may aggravate a disk problem or cause compression fractures if you have osteoporosis. Ask your physician if spinal manipulation is safe and helpful for you.

Electrical stimulation – Transcutaneous electronic nerve stimulation (TENS) may help stop pain by blocking nerve signals from reaching your brain. A physical therapist places electrodes on your skin near the area of your pain. TENS may relieve pain in your leg due to inflammation or compression of nerves in your back (sciatica), but it may provide little relief for chronic back pain.

Back schools – These programs, available in many communities, focus on managing back pain and preventing its recurrence. Classroom study generally involves back anatomy and function, followed by practice sessions on how to protect your back at home and work.

Exercise and physical therapy – Once your pain subsides, your doctor or a physical therapist can design an exercise program to improve your flexibility, strengthen your back and abdominal muscles and improve your posture.

Lastly, before you decide on back surgery, consider a second opinion. Surgery to remove a herniated disk is among the most frequently performed procedures in the United States. This surgery carries little risk, and the results usually are good. But long-term outcomes also are often similar following less-invasive treatments for injuries.