Low back pain is one of the most frequent complaints for which patients are seen in primary care. Low back pain has a substantial economic impact, estimated at $100 billion per year including direct and indirect costs. The evaluation of low back pain involves a thorough history and physical examination. Imaging is only indicated when a more serious underlying cause or neurologic abnormality is suspected. Abnormalities detected on imaging do not strongly correlate with symptoms. Generally, a specific underlying cause for low back pain is not identified. Treatment consists of a multidisciplinary approach with goal to maintain function and minimize disability.

Keywords

Acute low back pain

Chronic low back pain

Risk factors

Cause

Diagnosis

Imaging

Treatment

Sciatica

Key points

Introduction

Low back pain affects a significant proportion of the population.1–5 The precise incidence and prevalence of low back pain are difficult to characterize due to significant heterogeneity in the epidemiologic studies. In a survey of Saskatchewan adults, 84% of participants reported experiencing at least one episode of back pain in their lifetime.6 A 2002 US National Health Interview Study found that 26.4% of the 30,000 participants had experienced at least one full day of back pain in the past 3 months.7 A 2010 review article reported 1-year incidences of first time, any time, and recurrent low back pain episodes as ranging from 1.5% to 80%, and the 1-year prevalence of low back pain ranging from 0.8% to 82.5%.8 These findings are summarized in Table 1.

The incidence of low back pain peaks in the third decade of life. The prevalence increases until age 60 to 65 and then gradually declines.

Commonly reported risk factors for low back pain include physical, psychological, social, and occupational factors and are summarized in Table 2.2,6

Low back pain has an enormous social and economic impact. It is a leading cause of work absenteeism globally and the second most common cause of missed work days in the United States.9,10 Direct medical costs attributed to the evaluation and treatment of low back pain are estimated to exceed $33 billion annually in the United States. When the indirect costs of missed work and decreased productivity are added, the total costs exceed $100 billion each year.2

Primary care providers play a key role in the evaluation and treatment of low back pain. Indeed, low back pain is the chief complaint in about 2.3% of all ambulatory physician visits, representing about 15 million office visits per year, and is second only to upper respiratory symptoms as a symptom prompting office evaluation.7

Pathophysiology

Anatomy

There are 5 lumbar vertebrae, each of which is composed of a vertebral body, 2 pedicles, 2 lamina, 4 articular facets, and a spinous process. Between each pair of vertebrae are the foramina, openings through which pass the spinal nerves, radicular blood vessels, and sinuvertebral nerves. The spinal canal is formed anteriorly by the posterior surface of the vertebral bodies, intervertebral discs, and posterior longitudinal ligament, laterally by the pedicles, and posteriorly by the ligamentum flavum and lamina (Fig. 1).

In the normal spine, the anterior structures including the vertebral bodies and intervertebral discs perform weight-bearing and shock-absorbing functions. The posterolateral structures, including the vertebral arches, lamina, transverse, and spinous processes, provide protection for the spinal cord and nerve roots. Balance, flexibility, and stability are provided by the facet joints and paraspinous muscles and ligaments.