Evaluation and Treatment of Acute Low Back Pain

SCOTT KINKADE, M.D., M.S.P.H., University of Texas Southwestern Medical School, Dallas, Texas

	Patient information: A handout on low back pain, written by the author of this article and by Richard B. Sisson, a medical student at Georgetown University School of Medicine, is provided on page 1190.
	A PDF version of this document is available. Download PDF now (8 pages/240 KB).

Acute low back pain with or without sciatica usually is self-limited and has no serious underlying pathology. For most patients, reassurance, pain medications, and advice to stay active are sufficient. A more thorough evaluation is required in selected patients with "red flag" findings associated with an increased risk of cauda equina syndrome, cancer, infection, or fracture. These patients also require closer follow-up and, in some cases, urgent referral to a surgeon. In patients with nonspecific mechanical low back pain, imaging can be delayed for at least four to six weeks, which usually allows the pain to improve. There is good evidence for the effectiveness of acetaminophen, nonsteroidal anti-inflammatory drugs, skeletal muscle relaxants, heat therapy, physical therapy, and advice to stay active. Spinal manipulative therapy may provide short-term benefits compared with sham therapy but not when compared with conventional treatments. Evidence for the benefit of acupuncture is conflicting, with higher-quality trials showing no benefit. Patient education should focus on the natural history of the back pain, its overall good prognosis, and recommendations for effective treatments. (Am Fam Physician 2007;75:1181-8, 1190-2. Copyright © 2007 American Academy of Family Physicians.)

Low back pain affects a reported 5.6 percent of U.S. adults each day,1 and 18 percent report having had back pain in the previous month.2 The lifetime prevalence of low back pain is estimated to be at least 60 to 70 percent.3,4 Although most patients self-treat back pain and only 25 to 30 percent seek medical care,5,6 back pain is one of the most common reasons for visits to family physicians. Family physicians treat more patients with back pain than any other subspecialist, and about as many as orthopedists and neurosurgeons combined.3

SORT: KEY RECOMMENDATIONS FOR PRACTICE
Clinical recommendation	Evidence rating	References
In the absence of "red flag" findings or signs of cauda equina syndrome, four to six weeks of conservative care is appropriate for patients with acute low back pain.	C	16-20
Nonsteroidal anti-inflammatory drugs, acetaminophen, and skeletal muscle relaxants are effective first-line medications in the treatment of acute, nonspecific low back pain.	A	22, 24-26
Bed rest for more than two or three days in patients with acute low back pain is ineffective and may be harmful. Patients should be instructed to remain active.	A	32, 33
Education about activity, aggravating factors, natural history, and expected time course for improvement may speed recovery of patients with acute low back pain and prevent chronic back pain.	C	34, 37
Specific back exercises for patients with acute low back pain are not helpful.	A	39
Heat therapy may be helpful in reducing pain and increasing function in patients with acute low back pain.	B	45-50
Spinal manipulative therapy for acute low back pain may offer some short-term benefits but probably is no more effective than usual medical care.	B	51-54
A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, see page 1135 or http://www.aafp.org/afpsort.xml.

Diagnosis

Acute low back pain is defined as pain that occurs posteriorly in the region between the lower rib margin and the proximal thighs and that is of less than six weeks' duration. Sciatica is pain that radiates down the posterior or lateral leg beyond the knee. Knowing the prevalence of various etiologies of back pain, looking for "red flag" findings (which indicate a serious underlying condition) in the history and physical examination, and performing some basic physical examination maneuvers allow physicians to accurately and quickly classify most causes of back pain.

differential diagnosis

Serious conditions such as cancer, infection, and visceral disease account for only a small percentage of back pain cases, and vertebral compression fractures account for less than 5 percent (Table 13,7-13). Herniated disks, which are often managed initially like lumbar strains, account for only 4 percent of back pain cases.3 Most back pain is nonspecific lumbar strain or idiopathic back pain. The prevalence of these disorders varies with age, with herniated disks being most common in patients between 20 and 50 years, and degenerative processes (e.g., spinal stenosis, osteoporotic fractures) more likely in older patients.7,10

Table 1. Differential Diagnosis of Low Back Pain
Condition (prevalence*)	Signs and symptoms
Mechanical low back pain (97%)
Lumbar strain or sprain (≥ 70%)	Diffuse pain in lumbar muscles; some radiation to buttocks
Degenerative disk or facet process (10%)	Localized lumbar pain; similar findings to lumbar strain
Herniated disk (4%)	Leg pain often worse than back pain; pain radiating below knee
Osteoporotic compression fracture (4%)	Spine tenderness; often history of trauma
Spinal stenosis (3%)	Pain better when spine is flexed or when seated, aggravated by walking downhill more than uphill; symptoms often bilateral
Spondylolisthesis (2%)	Pain with activity, usually better with rest; usually detected with imaging; controversial as cause of significant pain
Nonmechanical spinal conditions (1%)
Neoplasia (0.7%)	Spine tenderness; weight loss
Inflammatory arthritis (0.3%)	Morning stiffness, improves with exercise
Infection (0.01%)	Spine tenderness; constitutional symptoms
Nonspinal/visceral disease (2%)
Pelvic organs-prostatitis, pelvic inflammatory disease, endometriosis	Lower abdominal symptoms common
Renal organs-nephrolithiasis, pyelonephritis	Usually involves abdominal symptoms; abnormal urinalysis
Aortic aneurysm	Epigastric pain; pulsatile abdominal mass
Gastrointestinal system-pancreatitis, cholecystitis, peptic ulcer	Epigastric pain; nausea, vomiting
Shingles	Unilateral, dermatomal pain; distinctive rash
*-Estimated percentage of patients with this condition among all adult patients with low back pain in primary care. Information from references 3 and 7 through 13.

The natural history of back pain is favorable overall; studies show that 30 to 60 percent of patients recover in one week, 60 to 90 percent recover in six weeks, and 95 percent recover in 12 weeks.7,14 However, relapses and recurrences are common, occurring in about 40 percent of patients within six months.15