See related patient information handout on low back pain , written by the author of this article.

Acute low back pain is commonly treated by family physicians. In most cases, only conservative therapy is needed. However, the history and physical examination may elicit warning signals that indicate the need for further work-up and treatment. These “red flags” include a history of trauma, fever, incontinence, unexplained weight loss, a cancer history, long-term steroid use, parenteral drug abuse, and intense localized pain and an inability to get into a comfortable position. Treatment usually consists of non-steroidal anti-inflammatory agents or acetaminophen and a gradual return to usual activities. Surgery is reserved for use in patients with severe neurologic deficits and, possibly, those with severe symptoms that persist despite adequate conservative treatment.

Low back pain is a problem that family physicians confront in their patients almost daily. It is so prevalent that the Agency for Health Care Policy and Research (AHCPR) of the U.S. Department of Health and Human Services has developed and published national guidelines to assist primary care physicians in the appropriate care of affected patients.1 A 23-member multidisciplinary committee compiled the guidelines, which focus on low back pain of less than three months' duration. This review incorporates many of that committee's recommendations.

Clinical Categories of Low Back Pain Jump to section + Abstract

Epidemiology

Duration of Symptoms

Clinical Categories of Low Back Pain

History

Physical Examination

Laboratory Tests

Radiographic Evaluation

Treatment

Difficulties in Diagnosing Acute Low Back Pain

References Low back pain can be caused by many conditions, both serious and benign. Because of this, the AHCPR has grouped back pain into three categories: potentially serious spinal conditions, sciatica and nonspecific back symptoms. POTENTIALLY SERIOUS SPINAL CONDITIONS Spinal tumor, infection, fracture and the cauda equina syndrome are potentially serious causes of acute low back pain. These conditions are suggested by characteristic findings from the history and physical examination (Table 1). Immediate further work-up and treatment are usually needed. View/Print Table TABLE 1 Causes of Low Back Pain Condition Clinical clues Nonspecific back pain (mechanical back pain, facet joint pain, osteoarthritis, muscle sprains, spasms) No nerve root compromise, localized pain over lumbosacral area Sciatica (herniated disc) Back-related lower extremity symptoms and spasm in radicular pattern, positive straight leg raising test Spine fracture (compression fracture) History of trauma, osteoporosis, localized pain over spine Spondylolysis Affects young athletes (gymnastics, football, weight lifting); pain with spine extension; oblique radiographs show defect of pars interarticularis Malignant disease (multiple myeloma), metastatic disease Unexplained weight loss, fever, abnormal serum protein electrophoresis pattern, history of malignant disease Connective tissue disease (systemic lupus erythematosus) Fever, increased erythrocyte sedimentation rate, positive for antinuclear antibodies, scleroderma, rheumatoid arthritis Infection (disc space, spinal tuberculosis) Fever, parenteral drug abuse, history of tuberculosis or positive tuberculin test Abdominal aortic aneurysm Inability to find position of comfort, back pain not relieved by rest, pulsatile mass in abdomen Cauda equina syndrome (spinal stenosis) Urinary retention, bladder or bowel incontinence, saddle anesthesia, severe and progressive weakness of lower extremities Hyperparathyroidism Insidious, associated with hypercalcemia, renal stones, constipation Ankylosing spondylitis (morning stiffness) Mostly men in their early 20s, positive for HLA-B27 antigen, positive family history, increased erythrocyte sedimentation rate Nephrolithiasis Colicky flank pain radiating to groin, hematuria, inability to find position of comfort TABLE 1 Causes of Low Back Pain Condition Clinical clues Nonspecific back pain (mechanical back pain, facet joint pain, osteoarthritis, muscle sprains, spasms) No nerve root compromise, localized pain over lumbosacral area Sciatica (herniated disc) Back-related lower extremity symptoms and spasm in radicular pattern, positive straight leg raising test Spine fracture (compression fracture) History of trauma, osteoporosis, localized pain over spine Spondylolysis Affects young athletes (gymnastics, football, weight lifting); pain with spine extension; oblique radiographs show defect of pars interarticularis Malignant disease (multiple myeloma), metastatic disease Unexplained weight loss, fever, abnormal serum protein electrophoresis pattern, history of malignant disease Connective tissue disease (systemic lupus erythematosus) Fever, increased erythrocyte sedimentation rate, positive for antinuclear antibodies, scleroderma, rheumatoid arthritis Infection (disc space, spinal tuberculosis) Fever, parenteral drug abuse, history of tuberculosis or positive tuberculin test Abdominal aortic aneurysm Inability to find position of comfort, back pain not relieved by rest, pulsatile mass in abdomen Cauda equina syndrome (spinal stenosis) Urinary retention, bladder or bowel incontinence, saddle anesthesia, severe and progressive weakness of lower extremities Hyperparathyroidism Insidious, associated with hypercalcemia, renal stones, constipation Ankylosing spondylitis (morning stiffness) Mostly men in their early 20s, positive for HLA-B27 antigen, positive family history, increased erythrocyte sedimentation rate Nephrolithiasis Colicky flank pain radiating to groin, hematuria, inability to find position of comfort SCIATICA Back-related lower extremity symptoms suggest nerve root compromise. Sciatica is often debilitating but, in most cases, the pain abates with conservative therapy. NONSPECIFIC BACK SYMPTOMS Some patients have symptoms primarily in the back that suggest neither nerve root compromise nor a serious underlying condition.1 Mechanical low back pain is in this category. These patients also usually improve with conservative treatment. With this clinical classification, the examiner can use the history and physical findings to specify the type of back pain affecting the patient and properly treat patients who have potentially serious spinal conditions.

History Jump to section + Abstract

Epidemiology

Duration of Symptoms

Clinical Categories of Low Back Pain

History

Physical Examination

Laboratory Tests

Radiographic Evaluation

Treatment

Difficulties in Diagnosing Acute Low Back Pain

References The diagnosis of low back pain requires a careful history to determine whether the causes are mechanical, or secondary and more threatening. Mechanical causes of acute low back pain include dysfunction of the musculoskeletal and ligamentous structures. Pain can originate from the disc, annulus, facet joints and muscle fibers. Mechanical low back pain generally has a favorable outcome, but back pain with a secondary cause requires treatment for the underlying condition. Fortunately, secondary causes of low back pain are much less frequent than mechanical causes. An important consideration in the patient's history is age. Patients older than 50 and younger than 20 are more likely to have secondary causes. Clinical findings that may indicate an underlying disease are listed in Table 1. Less common secondary causes of acute low back pain include metabolic diseases, inflammatory rheumatologic disorders, referred pain from other sources, Paget's disease, fibromyalgia and psychogenic pain8,9 (Table 2). View/Print Table TABLE 2 Differential Diagnosis of Low Back Pain Primary mechanical derangements Ligamentous strain Muscle strain or spasm Facet joint disruption or degeneration Intervertebral disc degeneration or herniation Vertebral compression fracture Vertebral end-plate microfractures Spondylolisthesis Spinal stenosis Diffuse idiopathic skeletal hyperostosis Scheuermann's disease (vertebral epiphyseal aseptic necrosis) Infection Epidural abscess Vertebral osteomyelitis Septic discitis Pott's disease (tuberculosis) Nonspecific manifestation of systemic illness Bacterial endocarditis Influenza Neoplasia Epidural or vertebral carcinomatous metastases Multiple myeloma, lymphoma Primary epidural or intradural tumors Metabolic disease Osteoporosis Osteomalacia Hemochromatosis Ochronosis Inflammatory rheumatologic disorders Ankylosing spondylitis Reactive spondyloarthropathies (including Reiter's syndrome) Psoriatic arthropathy Polymyalgia rheumatica Referred pain Abdominal or retroperitoneal visceral process Retroperitoneal vascular process Retroperitoneal malignancy Herpes zoster Paget's disease of bone Primary fibromyalgia Psychogenic pain Malingering TABLE 2 Differential Diagnosis of Low Back Pain Primary mechanical derangements Ligamentous strain Muscle strain or spasm Facet joint disruption or degeneration Intervertebral disc degeneration or herniation Vertebral compression fracture Vertebral end-plate microfractures Spondylolisthesis Spinal stenosis Diffuse idiopathic skeletal hyperostosis Scheuermann's disease (vertebral epiphyseal aseptic necrosis) Infection Epidural abscess Vertebral osteomyelitis Septic discitis Pott's disease (tuberculosis) Nonspecific manifestation of systemic illness Bacterial endocarditis Influenza Neoplasia Epidural or vertebral carcinomatous metastases Multiple myeloma, lymphoma Primary epidural or intradural tumors Metabolic disease Osteoporosis Osteomalacia Hemochromatosis Ochronosis Inflammatory rheumatologic disorders Ankylosing spondylitis Reactive spondyloarthropathies (including Reiter's syndrome) Psoriatic arthropathy Polymyalgia rheumatica Referred pain Abdominal or retroperitoneal visceral process Retroperitoneal vascular process Retroperitoneal malignancy Herpes zoster Paget's disease of bone Primary fibromyalgia Psychogenic pain Malingering In general, clues to secondary causes of low back pain can be found in the history and physical examination. These are referred to as “red flags,” and they warrant further diagnostic work-up and immediate treatment (Table 3). View/Print Table TABLE 3 Red Flags for Acute Low Back Pain History Cancer Unexplained weight loss Immunosuppression Prolonged use of steroids Intravenous drug use Urinary tract infection Pain that is increased or unrelieved by rest Fever Significant trauma related to age (e.g., fall from a height or motor vehicle accident in a young patient, minor fall or heavy lifting in a potentially osteoporotic or older patient or a person with possible osteoporosis) Bladder or bowel incontinence Urinary retention (with overflow incontinence) Physical examination Saddle anesthesia Loss of anal sphincter tone Major motor weakness in lower extremities Fever Vertebral tenderness Limited spinal range of motion Neurologic findings persisting beyond one month TABLE 3 Red Flags for Acute Low Back Pain History Cancer Unexplained weight loss Immunosuppression Prolonged use of steroids Intravenous drug use Urinary tract infection Pain that is increased or unrelieved by rest Fever Significant trauma related to age (e.g., fall from a height or motor vehicle accident in a young patient, minor fall or heavy lifting in a potentially osteoporotic or older patient or a person with possible osteoporosis) Bladder or bowel incontinence Urinary retention (with overflow incontinence) Physical examination Saddle anesthesia Loss of anal sphincter tone Major motor weakness in lower extremities Fever Vertebral tenderness Limited spinal range of motion Neurologic findings persisting beyond one month

Physical Examination Jump to section + Abstract

Epidemiology

Duration of Symptoms

Clinical Categories of Low Back Pain

History

Physical Examination

Laboratory Tests

Radiographic Evaluation

Treatment

Difficulties in Diagnosing Acute Low Back Pain

References The physical examination is not as important as the history in identifying secondary causes of acute low back pain. Nevertheless, certain aspects of the physical examination are considered important. GAIT AND POSTURE Observation of the patient's walk and overall posture is suggested for all patients with low back pain. Scoliosis may be functional and may indicate underlying muscle spasm or neurogenic involvement. RANGE OF MOTION The examiner should record the patient's forward flexion, extension, lateral flexion and lateral rotation of the upper torso. Pain with forward flexion is the most common response and usually reflects mechanical causes. If pain is induced by back extension, spinal stenosis should be considered. Unfortunately, the evaluation of spinal range of motion has limited diagnostic use,10 although it may be helpful in planning and monitoring treatment. PALPATION OR PERCUSSION OF THE SPINE Point tenderness over the spine with palpation or percussion may indicate fracture or an infection involving the spine. Palpating the paraspinous region may help delineate tender areas or muscle spasm. HEEL-TOE WALK AND SQUAT AND RISE A patient unable to walk heel to toe, and squat and rise may have severe cauda equina syndrome or neurologic compromise. PALPATION OF THE SCIATIC NOTCH Tenderness over the sciatic notch with radiation to the leg often indicates irritation of the sciatic nerve or nerve roots. STRAIGHT LEG RAISING TEST With the patient in the supine position, each leg is raised separately until pain occurs. The angle between the bed and the leg should be recorded. Pain occurring when the angle is between 30 and 60 degrees is a provocative sign of nerve root irritation (Figure 1, top). Bending the knee while maintaining hip flexion should relieve the pain, and pressure in the popliteal region should worsen it (popliteal compression test).11 If placing the knee back in full extension during straight leg raising and dorsiflexing the ankle also increase the pain (Lasègue's sign), nerve root and sciatic nerve irritation is likely. The rightsholder did not grant rights to reproduce this item in electronic media. For the missing item, see the original print version of this publication. FIGURE 1. The result of straight leg raising is positive in 95 percent of patients with a proven herniated disc at surgery, but it is also positive in 80 to 90 percent of patients without any form of disc protrusion at surgery.12 In contrast, crossed straight leg raising is less sensitive but much more specific for disc herniation. In the crossed straight leg raising test, the contralateral, uninvolved leg is raised (Figure 1, bottom). The test result is positive when pain is produced. REFLEXES AND MOTOR AND SENSORY TESTING Testing knee and ankle reflexes in patients with radicular symptoms often helps determine the level of spinal cord compromise. An altered knee or ankle reflex alone does not suggest the need for invasive management because this finding is generally transient and fully reversible.8 Weakness with dorsiflexion of the great toes and ankle may indicate L5 and some L4 root dysfunction. Sensory testing of the medial (L4), dorsal (L5) and lateral (S1) aspects of the foot may also detect nerve root dysfunction.1 LIMITED NEUROLOGIC TESTING In the primary care of patients with low back pain and leg symptoms, the neurologic examination can be limited to just a few tests. These include the testing of dorsiflexion strength of the ankle and great toe, ankle reflexes and light touch over aspects of the foot, as well as the straight leg raising test. This abbreviated neurologic examination of the lower extremities allows the detection of most clinically important radiculopathy related to lumbar disc herniation. If patients with abnormal findings on these tests do not show improvement by one month, further diagnostic work-up or referral to a specialist is necessary.8 Those with progressive symptoms should undergo further evaluation without delay.