General Considerations
Low back pain (LBP), discomfort, tension, or stiffness below the costal margin and above the inferior gluteal folds, is one of the most common conditions encountered in primary care, second only to the common cold. LBP has an annual incidence of 5%, and a lifetime prevalence of 60%-90%. It is the leading cause of disability in the United States for adults younger than 45 years of age, and is responsible for one-third of workers’ compensation costs and accounts for direct medical costs in excess of $38 billion per year. At any given time 1% of the US population is chronically disabled and another 1% temporarily disabled as a result of back pain. Numerous studies report a favorable natural history for acute and subacute LBP, with up to 90% of patients regaining function within 6-12 weeks with or without physician intervention. Recent studies, however, suggest that back pain is often recurrent and chronically disabling. Approximately 85% of back pain has no readily identifiable cause, and up to one-third of all patients will develop chronic low back pain. This chapter reviews a detailed evidence-based approach to the assessment, diagnosis, and management of the adult patient with acute, subacute, and chronic LBP.
Prevention
LBP is a heavy medical and financial burden to not only the patients who are experiencing the ailment, but also to society. The US Preventive Services Task Force recently produced a recommendation statement on primary care interventions to prevent low back pain in adults. Currently there is insufficient evidence to support or rebuke routine use of exercise as a preventive for low back pain. However, regular physical activity has been shown to be beneficial in the treatment and the limitation of recurrent episodes of chronic low back pain. Lumbar supports (back belts) have not been found effective in the prevention of low back pain. Work site interventions, including education on lifting techniques, have been shown to have some short-term effects, on decreasing lost time from work for patients with back pain.
Risk factor modifications may be the only way to truly prevent LBP. These risk factors can be classified as individual, psychosocial, occupational, and anatomic. Table 24-1 lists the prominent risk factors for LBP.
| Individual | Psychosocial | Occupational | Anatomic |
|---|---|---|---|
| Increasing age | Stress | Monotonous tasks | Disc space narrowing |
| Smoking | Depressed mood | Low control job | Facet joint arthritis |
| History | Decreased cognition | Manual handling of materials | Synovial cysts |
| Obesity | Somatization | Job dissatisfaction | Lumbo-sacral transitional vertebra |
| Education level | Long duration of pain | Night shift work | Schmoral nodes |
| Unemployment | Fear avoidance behavior | Bending, twisting, pulling, pushing, | Annular disruption |
| High birth weight | Whole-body vibration | Spondylolysis | |
| High levels of pain | Lifting more than 3/4 of day | ||
| Unavailability of light duty | |||
| High pressure on time | |||
| Coworker socialization |
Clinical Findings
The key elements in the correct diagnosis and management of the issues surrounding the causes of LBP include an evaluation for serious health problems, screening for red and yellow flags (Tables 24-2 and 24-3), symptom control for acute and subacute LBP, and follow-up evaluation of patients whose condition worsens or fails to improve. The first step is the accurate and timely identification of clinical conditions for which low back pain is a symptom.
| Condition | Red Flag | Action |
|---|---|---|
| Cancer | History of cancer Unexplained weight loss Age ≥50 Failure to improve with therapy Pain ≥4-6 wk Night/rest pain | If malignant disease of the spine is suspected, imaging is indicated and CBC and ESR should be considered. Identification of possible primary malignancy should be investigated, eg, PSA, mammogram, UPEP/SPEP/IPEP. |
| Infection | Fever History of intravenous drug use Recent bacterial infection: UTI, skin, pneumonia Immunocompromised states (steroid, organ transplants, diabetes, HIV) Rest pain | If infection in the spine is suspected, MRI, CBC, ESR and/or UA are indicated. |
| Cauda equina syndrome | Urinary retention or incontinence Saddle anesthesia Ana sphincter tone decrease/fecal incontinence Bilateral lower extremity weakness/numbness or progressive neurologic deficit | Request immediate surgical consultation. |
| Fracture | Use of corticosteroids Age ≥70 or history of osteoporosis Recent significant trauma | Appropriate imaging and surgical consultation. |
| Acute abdominal aneurysm | Abdominal pulsating mass Other atherosclerotic vascular disease Rest/night pain Age ≥ 60 | Appropriate imaging (ultrasound) and surgical consultation. |
| Significant herniated nucleus pulposus (HNP) | Major muscle weakness | Appropriate imaging and surgical consultation. |
| Belief Systems | Comorbid Conditions |
|---|---|
Fear Avoidance Expectation of pain with normal activity Excessive focus on pain Feeling out of control Passivity toward rehabilitation | Lack of sleep secondary to pain History of other disabling injuries or conditions |
Affective Factors Poor work history Poor compliance with exercise Withdrawal from activities History of substance abuse Depression Irritability Anxiety Lack of socialization History of physical or psychological abuse | Waddel Signs Pain with axial loading of the spine Superficial tenderness to palpation (light touch) Overreaction (pain out of proportion to physical findings) Straight leg raise test improves with distraction Regional weakness |
A careful medical history and physical examination is critical in determining the presence of a more serious condition in the patient presenting with acute LBP. On examining the patient, the primary care provider must look for “red and yellow flags” that indicate the presence of a significant medical or psychological condition. If any red flags are identified, patients requiring emergent or urgent care should be given immediate consultation or referral to the appropriate specialist. Nonemergent patients with red flags should be scheduled for the appropriate diagnostic test to determine if they have a condition that requires a referral. If any yellow flags are identified it signifies the presence of psychological distress and strongly correlates to chronicity and poor patient outcomes in both pain control and disability. When yellow flags are identified early, an interdisciplinary approach should be considered.
The history should focus on the location of the pain, the mechanism of injury (what was the patient doing when he/she first noticed the pain, was it insidious or was there a specific trauma or activity), the character (mechanical, radicular, caludicant, or nonspecific), and duration of the pain (acute: less than 6 weeks, subacute: between 6 and 12 weeks, or chronic: greater than 12 weeks). The provider must identify neurologic symptoms (bowel/bladder symptoms, weakness in the extremities, saddle anesthesia) suggestive of cauda equina syndrome (CES: a true neurosurgical emergency). The functional status of the patient should be noted as should any exacerbating or ameliorating factors. The presence of fever, weight loss, and night pain are particularly concerning as these could be pointing to a more serious disease, such as an underlying malignancy. The social history should include information about drug use/abuse, intravenous (IV) drug use, tobacco use, and the presence of physical demands at work, and the presence of psychosocial stressors. Past medical and surgical history should also be obtained, particularly a history of previous spinal surgery or immunosuppression (history of cancer, steroid use, HIV). A thorough history enables the primary care provider to identify any “red and/or yellow flags” that require a more extensive workup to rule out a potentially serious and disabling disease processes.
The physical examination supplements the information obtained in the history by helping to identify underlying serious medical conditions or possible serious neurologic compromise. The primary elements of the physical examination are inspection, palpation, observation (including range of motion testing), and a specialized neuromuscular evaluation. The examination should start with an evaluation of the spinal curvature, lumbar range of motion, noting the amount of pain free movement. Palpation should include the paraspinal muscles, the spinous processes, the sacroiliac joints, the piriformis muscles, and the position of the pelvic bones. Because the lumbar spine is kinetically linked to the pelvis, (particularly the sacroiliac area), pain from the pelvis is often referred to the lumbar spine. Hip flexors and hamstring flexibility should also be assessed as a potential cause for the pain.
The neurologic evaluation should include Achilles (S1) and patellar tendon(L2-L4) reflex testing, ankle and great toe dorsiflexion (L4-L5) and plantarflexion (S1) strength, as well as the location of sensory complaints (dermatomes involved). Light touch testing for sensation in the medial (L4), dorsal (L5), and lateral (S1) aspects of the foot should also be performed. In patients presenting with acute LBP and no specific limb complaints, a more elaborate neurologic examination is not usually necessary. A seated and supine straight leg raise test (SLR) evaluates for nerve root impingement. This abbreviated neurologic evaluation of the lower extremity allows detection of clinically significant nerve root compromise at the L4-L5 or L5-S1 levels. These two sites make up over 90% of all significant radiculopathy secondary to lumbar disc herniation. Because this abbreviated examination may fail to diagnose some of the less common causes of LBP, any patient who has not improved in 4-6 weeks should return for further evaluation.
All patients, with acute LBP should be risk stratified with an initial assessment attempting to identify red flags-responses or findings in the history and physical examination that indicate a potentially serious underlying condition, such as a fracture, tumor, infections, abdominal aneurysm, or CES that can lead to considerable patient morbidity and/or mortality. These clinical clues (red flags) include a history of major trauma, minor trauma in patients older than 50 years of age, persistent fever, history of cancer, metabolic disorder, major muscle weakness, bladder or bowel dysfunction, saddle anesthesia, decreased sphincter tone, and unrelenting night pain. Red flags risk stratify the patient to an increased risk and should prompt an earlier clinical action, such as imaging or laboratory work up. See Table 24-2 for a listing of red flags and their related conditions.
Psychosocial factors also significantly affect pain and function in LBP patients. These psychosocial factors are known as “yellow flags” and are better predictors of treatment outcomes than physical factors in some patients. These yellow flags are listed in Table 24-3.
