Low Back Pain

Department of the Navy
Bureau of Medicine and Surgery

Low back problems affect virtually everyone at some time during their life. The prevalence in working-age adults is 50 percent with 10-20 percent of these seeking medical care. It is a common presenting complaint to the GMO and perhaps the most common cause of lost productivity. Low back pain is the most common cause of disability for those under age 45. For this reason it is imperative that the GMO be competent in assessing and treating low back pain.

This chapter will focus on acute low back pain, which will be defined as activity intolerance due to lower back or back related leg symptoms of less than 3 months duration. Nearly 90 percent of patients spontaneously recover from low back pain symptoms and resume normal daily activities within 3 months.

A focused medical history and physical examination are sufficient to assess the patient with acute or recurrent limitations due to low back symptoms less than 4 weeks of duration. A "red flag" is defined as a debilitating condition or disease that should be considered in the work-up of every patient.

Red Flags

• Fractures.
  Major trauma such as vehicle accident, aircraft mishap, or fall from height.

• Possible tumor or Infection. Look for any history of cancer. Constitutional symptoms can include recent fever, chills, or unexplained weight loss. Look for a source of an infection, such as urinary tract infection, IV drug abuse, or immune suppression (steroids, positive HIV). A pattern of worsening back pain at night, worse when supine. (Note: spinal cancer is less likely in active duty age range).

• Possible Cauda Equina Syndrome. Evaluate for saddle anesthesia, bladder dysfunction, such as urinary retention, increased frequency, or overflow incontinence. Also assess for a severe or progressive neurologic deficit in the lower extremities.

Symptoms can then be classified into one of three working categories:

• Potentially serious spinal conditions - tumor, infection, spinal fracture, decompression sickness (Type I), or a major neurologic compromise, such a cauda equina syndrome.

• Sciatica. Back related lower limb symptoms suggesting lumbosacral nerve root compromise or compression.

• Nonspecific back symptoms. These occur primarily in the back and suggesting neither nerve root compromise nor a serious underlying condition.

These questions are directed primarily at activity tolerance, not pain.

• What are your symptoms? Do you have pain, numbness, weakness, stiffness, onset acute or gradual?

• Location? - primarily in back, leg, or both?

• How do these symptoms limit you? How long can you sit, stand, and walk? How much weight can you lift?

• When did the current limitations begin and how long have your activities been limited? (More than 4 weeks?) Have you had similar episodes previously? Have you had any previous testing or treatment?

• What do you hope we can accomplish during this visit?

Physical Examination

The physical examination should include:

• Observations of the patient, including gait.

• Regional back exam.

• Neurologic screening.

• Testing for sciatic nerve root tension.

Addressing Red Flags

Physical examination evidence of severe neurologic compromise that correlates with the medical history may indicate a need for immediate consultation. The examination may further modify suspicions of tumor, infection, or significant trauma. A medical history suggestive of nonspinal pathology mimicking a back problem may warrant examination of the chest, abdomen, pelvis, pulses, or other areas.

Observation and Regional Back Examination

Check for limping; guarding of lumbar motion (guarding in all plains may suggest spinal infection); vertebral point tenderness (this may suggest fracture or infection).

Neurologic Screening

Identify any nerve root impairment, peripheral neuropathy or spinal cord dysfunction. Remember that over 90 percent of all clinically significant, lower extremity radiculopathies due to disc herniation involve either the L5 or S1 nerve root at the L4-L5 or L5-S1 discs level.

• Testing for muscle strength

  • Test toe walking (S1); heel walking (L5 and some L4); do a single squat and rise (quadriceps = L4); dorsiflexion of great toe (L5); hamstrings contraction (L5); and toe flexors (S1).

• Circumferential measurements

  • Muscle atrophy can be detected by circumferential measurements of the calf and thigh bilaterally. Differences of 2 cm in measurements of the two limbs may be normal variation.

• Reflexes

  • Test the ankle jerk (S1); and the knee jerk (L4). Up-going toes with planter stroking (Babinski or plantar response) may indicate upper motor neuron abnormalities (such as myelopathy or demyelinating disease) rather than a common low back problem.

• Sensory Examination

  • Test light touch or pressure in the medial (L4), dorsal (L5), and lateral (S1) aspects of the foot.

Clinical tests for sciatic tension

The straight leg raising (SLR) test produces leg pain by stretching the L5 and/or S1 nerve roots. Performance testing involves having the patient lie in a supine position. Place your hand over the anterior thigh and your other hand beneath the heel. Be certain that the leg is straight and ask the patient to relax. Gradually raise the leg at the heel while keeping the knee extended and allowing for simultaneous flexion of the hip. Ask the patient to state when the symptoms occur. Ask where the pain is felt and where the most distal area of discomfort is located (back, hip, thigh, knee, or below the knee). Pain below the knee at less than 70 degrees of straight leg raising, aggravated by dorsiflexion of the ankle and relieved by ankle planter flexion or external limb rotation, is most suggestive of tension on the L5 or S1 nerve root related to disc herniation. Reproducing back pain alone with SLR testing does not indicate significant nerve root tension.

Crossover pain

Pain is elicited in the affected leg (sciatica) while the well limb is straight leg raised. Crossover pain is a stronger indication of nerve root compression than pain elicited from "straight leg raising" (SLR) the painful limb.

Sitting knee extension

This is also used to test for sciatic tension. The patient with significant nerve root irritation tends to complain or lean backward in order to reduce tension on the nerve. While the patient is sitting on the table with both hips and knees are flexed at 90 degrees, slowly extend the knee as if evaluating the patella or bottom of the foot. This maneuver stretches nerve roots as much as a moderate degree of supine SLR.

Initial Care Patient Education

Back education will vary from patient to patient. If no red flags are discovered during the initial assessment, reassure the patient that no dangerous problems have been found and that a rapid recovery can be expected. If the patient does not recover in several weeks, a repeat medical evaluation including special studies should be recommended. Also review the type of treatment and activities that the patient has followed since the last visit.

Patient comfort

The vast majority of patients will obtain adequate comfort with a prudent restriction of activities and non-prescription analgesics.

Medications

The safest effective medication is for pain relief is acetaminophen. NSAIDs including aspirin and Ibuprofen, are also effective but may cause gastrointestinal irritation / ulceration or (less commonly) renal or allergic problems. Acetaminophen may also be used safely in combination with NSAIDs. Muscle relaxants are no more effective than NSAIDs either by themselves or in combination with NSAIDs. Remember muscle relaxants cause drowsiness. Opioids should be avoided whenever possible. If prescribed, these should be given for only a short period of time. Poor patient tolerance, risk of drowsiness, decreased reaction time, clouded judgement, and potential misuse are reasons not to prescribe narcotics. Patients should be warned about these potentially debilitating problems.

Physical Methods

• Manipulation

  • This type of treatment is defined as manual loading of the spine using short or long leverage methods. This therapy is safe and effective for patients (presuming that it is performed competently) in the first month of acute low back symptoms without radiculopathy. For patients with symptoms more than 1 month in duration, manipulation is safe but the efficacy is unproven. If manipulation has not resulted in symptomatic and functional improvement after 4 weeks, it should be stopped and the patient should be reevaluated.

• Traction

  • Traction applied to the spine has not been found to be effective in treating acute low back symptoms.

• Physical modalities

  • These therapies include massage, diathermy, ultrasound, cutaneous laser treatment, biofeedback, and transcutaneous electrical nerve stimulation (TENS). These provide no proven efficacy in the treatment of acute low back symptoms.

• Invasive Techniques

  • Needle acupuncture and injection procedures (injection of trigger points in the back; injections of facet joints; injection of steroids, lidocaine, or opiates in the epidural space) have no proven benefit in the treatment of acute low back symptoms.

• Other miscellaneous therapies

  • There is no evidence indicating that shoe lifts are effective in treating acute low back symptoms or limitations, especially when the difference in limb length is less than 2 cm. Shoe insoles are a safe and inexpensive option if requested by patients with low back symptoms who must stand for prolonged periods. Low back corsets and back belts do not appear beneficial for treating acute low back symptoms.

Activity Alteration

To avoid both undue back irritation and debilitation from inactivity, recommendations for alternate activity can be helpful. Most patients will not require bed rest. Prolonged bed rest (more than 4 days) has potential debilitating effects, and the efficacy in the treatment of acute low back problems is unproven. Two to four days of bed rest are reserved for patients with the most severe limitations (due primarily to leg pain).

Avoiding undue back irritation

Activities and improper posture can aggravate back symptoms. Patients limited by back symptoms can minimize the stress of lifting by keeping any lifted object close to the body at the level of the navel. Twisting, bending, and reaching while lifting also increases stress on the back. Sitting may aggravate symptoms for some patients as well. Advise patients to avoid prolonged sitting and to change position often. A soft support placed at the small of the back, armrests to support some bodyweight, and a slight recline of the chair back may make required sitting more comfortable.

Avoiding debilitation

Until the patient returns to normal activity, aerobic (endurance) conditioning exercise such as walking, stationary biking, swimming, and even light jogging may be recommended to avoid debilitation from inactivity. An incremental, gradually increasing regimen of aerobic exercise (up to 20-30 minutes daily) can usually be started within the first 2 weeks after symptoms have resolved. Such activities have been found to stress the back no more than sitting for an equal period of time on the side of a bed. Patients should be informed that exercise might increase symptoms slightly at first. If intolerable, some exercise alteration is usually helpful.

• Specific conditioning exercises for trunk muscles are more mechanically stressful to the back than aerobic exercise. Such exercises are not recommended during the first few weeks of symptoms, although they may later help patients regain and maintain activity tolerance.

• There is no evidence to indicate that back-specific exercise machines are effective for treating acute low back problems. Neither is there evidence that stretching of the back helps patients with acute symptoms.

Sitting and unassisted lifting

When prescribing work restrictions, remember that even moderately heavy unassisted lifting may aggravate back symptoms. Restrictions are intended to allow for improvements in recovery time. Restrictions should only be for a short period of time, and should never exceed 3 months since no benefit is apparent after 3 months.

Recommendations for sitting periods and weight lifting

• Employees without low back symptoms should not sit for more than 50 minutes without getting a break to get up and walk around.

• Employees with mild pain should not sit more than 30 minutes

• Employees with moderate pain should not sit for more than 20 minutes.

• Workers without back symptoms should not routinely be lifting more than 80 pounds (men) and 40 pounds (women).

• Workers with severe or moderate symptoms should not lift more than 20 pounds.

• Workers with mild symptoms should not lift more than 60 pounds (men) and 35 pounds (women).

Special studies and diagnostic considerations

Routine testing (laboratory tests, plain x-rays of the lumbosacral spine) and imaging studies are not recommended during the first month of activity limitation due to back symptoms except when significant trauma or other "red flag(s) " are present; then selected studies are appropriate, as is referral to a specialist.

Summary

The overall plan for otherwise healthy Navy members with acute low back symptoms should include the following guidelines:

• a competent and thoroughly documented evaluation.

• optimism that a full recovery is likely.

• pain control with mild analgesic medications.

• early return to modified work.

• appropriate work activity restrictions.

• a progressive program of exercise and escalating activity tolerance.

In the absence of red flags or severe neurological compromise, few patients should be at complete bed rest.

Reference

1. Agency for Health Care Policy and Research, Acute Low Back Pain problems in Adults, Clinical Guide and Quick Reference Guide #14, website address: (http://www.ahcpr.gov/).

Reviewed by CAPT John S. Webster, MC, USN, Chairman, Orthopedic Department, Residency Program Director, Naval Medical Center San Diego, and LCDR Geoffrey McCullen, MC, USNR, Director, Orthopedic Spine Service, Naval Medical Center San Diego, San Diego, CA (1999).