Low Back Pain Flashcards
Practice Essentials
Mechanical low back pain (LBP) remains the second most common symptom-related reason for seeing a physician in the United States. Of the US population, 85% will experience an episode of mechanical LBP at some point during their lifetime. Fortunately, the LBP resolves for the vast majority within 2-4 weeks.
Signs and symptoms
An important part of the physical examination is the general observation of the patient. The patient presents with pain in the low back region and often places his or her whole hand against the skin to indicate a regional pain; however, in some cases the patient may indicate a more precise location.
Interruption in bowel or bladder function should be a reminder to consider more serious causes of back pain such as a tumor, infection, or fracture.
Patients generally present with a history of an inciting event that produced immediate low back pain.
The most commonly reported histories include the following:
1. Lifting and/or twisting while holding a heavy object (eg, box, child, nursing home resident, a package on a conveyor)
- Operating a machine that vibrates
- Prolonged sitting (eg, long-distance truck driving, police patrolling)
- Involvement in a motor vehicle collision
Falls
Testing
The following tests are used when evaluating low back pain.
- Observe the patient walking into the office or examining room
- Observe the patient during the history-gathering portion of the visit for development, nutrition, deformities, and attention to grooming
- Measure blood pressure, pulse, respirations, temperature, height, and weight
- Inspect the back for signs of asymmetry, lesions, scars, trauma, or previous surgery
- Note chest expansion: If < 2.5 cm, this finding can be specific, but not sensitive, for ankylosing spondylitis
- Take measurements of the calf circumferences (at midcalf). Differences of less than 2 cm are considered normal variation
- Measure lumbar range of motion (ROM) in forward bending while standing (Schober test)
- Neurologic examination should test 2 muscles and 1 reflex representing each lumbar root to distinguish between focal neuropathy and root problems
- Measure leg lengths (anterior superior iliac spine to medial malleolus) if side-to-side discrepancy is suspected
- Use the inclinometer to measure forward, backward, and lateral bending. With the goniometer positioned over the head, measure trunk rotation
- Palpate the entire spine to identify vertebral tenderness that may be a nonspecific finding of fracture or other cause of low back pain
- Test for manual muscle strength in both lower extremities.
- Test for sensation and reflexes
- Imaging studies: Persistent pain may require CT scanning, diskography, and 3-phase bone scanning; electromyography and nerve conduction studies can help in the evaluation of neurologic symptoms or deficits
Management
Management of mechanical low back pain can be outlined in the following 6 steps:
1. Control of pain and the inflammatory process
- Restoration of joint ROM and soft tissue extensibility
- Improvement of muscular strength and endurance
- Coordination retraining
- Improvement of general cardiovascular condition
- Maintenance exercise programs
Surgical interventions for mechanical low back pain (LBP) are the last choice for treatment.
Pharmacological interventions for the relief of low back pain include acetaminophen, nonsteroidal anti-inflammatory drugs, topical analgesics, muscle relaxants, opioids, corticosteroids, antidepressants, and anticonvulsants.
Background
Mechanical low back pain (LBP) remains the second most common symptom-related reason for seeing a physician in the United States. Of the US population, 85% will experience an episode of mechanical LBP at some point during their lifetime. Fortunately, the LBP resolves for the vast majority within 2-4 weeks.
For individuals younger than 45 years, mechanical LBP represents the most common cause of disability and is generally associated with a work-related injury. For individuals older than 45 years, mechanical LBP is the third most common cause of disability, and a careful history and physical examination are vital to evaluation, treatment, and management.
Numerous treatment guidelines have been written regarding the evaluation, treatment, and management of LBP. [2, 3] Perhaps the most widely reviewed (and controversial) guideline was published in 1994 by the Agency for Health Care Policy and Research titled “Acute Lower Back Problems in Adults: Clinical Practice Guidelines.”
At the beginning of the 21st century, 750 national and international organizations partnered to create the Bone and Joint Decade (2002-2011). [5] This initiative involves patient and professional health care organizations, government agencies, and industries working collaboratively to increase the awareness of bone and joint diseases while increasing the information and research to address this major health care issue. Because 1 in 5 Americans will be age 65 or older by 2030, 65 million people (20% of the total population) will be affected by musculoskeletal impairments, with LBP ranking among the most common problems. Already, total direct and indirect costs for the treatment of LBP are estimated to be $100 billion annually.
The physiatrist represents one type of medical specialist who can evaluate, diagnose, treat, and manage LBP by using medical and nonsurgical procedures and interventions. The physiatrist may have the best functional understanding of all specialists in the treatment and management of mechanical LBP
Pathophysiology
Mechanical low back pain (LBP) generally results from an acute traumatic event, but it may also be caused by cumulative trauma. The severity of an acute traumatic event varies widely, from twisting one’s back to being involved in a motor vehicle collision. Mechanical LBP due to cumulative trauma tends to occur more commonly in the workplace.
Repetitive, compressive loading of the disks in flexion (eg, lifting) puts the disks at risk for an annular tear and internal disk disruption. Likewise, torsional forces on the disks can produce shear forces that may induce annular tears. (Degenerative disk forces are demonstrated in the image below.) The contents of the annulus fibrosis (nucleus pulposus) may leak through these tears. Central fibers of the disk are pain free, so early tears may not be painful. Samples of disk material taken at the time of autopsy reveal that the cross-linked profile of pentosidine, a component of the collagen matrix, declines. This may indicate the presence of increased matrix turnover and tissue remodeling
In lumbar flexion, the highest strains are recorded within the interspinous and supraspinous ligaments, followed by the intracapsular ligaments and the ligamentum flavum. In lumbar extension, the anterior longitudinal ligament experiences the highest strain. Lateral bending produces the highest strains in the ligaments contralateral to the direction of bending. Rotation generates the highest strains in the capsular ligaments.
Biomechanical Forces of the Low Back
Biomechanically, the movements of the lumbar spine consist of the cumulative motions of the vertebrae, with 80-90% of the lumbar flexion/extension occurring at the L4-L5 and L5-S1 intervertebral disks. The lumbar spine position most at risk for producing LBP is forward flexion (bent forward), rotation (trunk twisted), and attempting to lift a heavy object with out-stretched hands.
Axial loading of short duration is resisted by annular collagen fibers in the disk. Axial loading of a longer duration creates pressure to the annulus fibrosis and increased pressure to the endplates. If the annulus and endplate are intact, the loading forces can be adequately resisted. However, compressive muscular forces may combine with the loading forces to increase intradiskal pressure that exceeds the strength of the annular fibers.
Pathophysiology of Low Back-Different Studies
In a systematic study review, Chen et al investigated whether a sedentary lifestyle (which the authors defined as including sitting for prolonged periods at work and during leisure time) is a risk factor for LBP. Examining journal articles published between 1998 and 2006, they identified 8 high-quality reports (6 prospective cohort and 2 case-control studies). While 1 of the cohort studies reported a link between sitting at work and the development of LBP, the other investigations did not find a significant connection between a sedentary lifestyle and LBP. Chen and coauthors concluded that a sedentary lifestyle alone does not lead to LBP.
In a birth cohort study from 1980-2008, Rivinoja et al investigated whether lifestyle factors, such as smoking, being overweight or obese, and participating in sports, at age 14 years would predict hospitalizations in adulthood for LBP and sciatica. The authors found that 119 females and 254 males had been hospitalized at least once because of LBP or sciatica. Females who were overweight had an increased risk of second-time hospitalization and surgery. Smoking in males was linked with an increased risk of first-time nonsurgical hospitalization and second-time hospitalization for surgical treatment.
Similarly, a study by Yang and Haldeman, derived from the 2009-2012 National Health Interview Survey of the civilian US population, indicated that risk factors for LBP include current or previous smoking, current or previous alcohol use, lack of sleep, obesity, and lack of leisure-time physical activity.
The pathophysiology of mechanical LBP remains complex and multifaceted. Multiple anatomic structures and elements of the lumber spine (eg, bones, ligaments, tendons, disks, muscle) are all suspected to have a role. (See the images below.) Many of these components of the lumber spine have sensory innervation that can generate nociceptive signals representing responses to tissue-damaging stimuli. Other causes could be neuropathic (eg, sciatica). Most chronic LBP cases most likely involve mixed nociceptive and neuropathic etiologies.
Rates of Low Back Pain
United States
The lifetime prevalence of mechanical low back pain (LBP) in the United States is 60-80%. The prevalence of serious mechanical LBP (persisting >2 wk) is 14%. The prevalence of true sciatica (pain radiating down one or both legs) is approximately 2%.
Of all cases of mechanical LBP, 70% are due to lumbar strain or sprain, 10% are due to age-related degenerative changes in disks and facets, 4% are due to herniated disks, 4% are due to osteoporotic compression fractures, and 3% are due to spinal stenosis. All other causes account for less than 1% of cases.
Mechanical LBP is the most common cause of work-related disability in persons younger than 45 years in the United States.
International
Mechanical low back pain (LBP) exists in every culture and country. Worldwide, more disability is caused by LBP than by any other condition. [14, 15, 16] Estimates by numerous investigators indicate that at some point in their lives, 80% of all human beings experience LBP. Mechanical LBP becomes more prevalent in countries with higher per capita income and where more liberal policies and adequate funds provide for compensation (eg, Germany, Sweden, Belgium).
Etiology of Low Back Pain
Race
No published information suggests that race is a factor in the prevalence of mechanical low back pain.
Sex
The impact of sex on prevalence of low back pain (LBP) has not been established as well as the roles of other risk factors in LBP (eg, previous LBP, age). A reported 50-90% of women develop symptoms of LBP in the course of pregnancy. Discomfort generally develops in the very early weeks, more commonly in the third trimester. Age, race, occupation, baby’s weight, prepregnancy maternal weight, weight gain, number of children, exercise habits, sleeping posture, mattress type, and history of previous LBP have not shown any correlation with the development of LBP symptoms during pregnancy.
Age
Age has been shown to be associated more consistently with mechanical low back pain (LBP) than with sex. The prevalence of LBP during pregnancy appears to increase 5% for every 5 years of patient age. Sciatica (pain that radiates down one or both legs) is usually reported in persons aged 40-59 years. Women aged 60 years or older also report more low back symptoms.
Small overview of Treatment possibilities
Mechanical low back pain (LBP) is not a life-threatening illness. Unfortunately, it does have a far-reaching impact on medical care expenditures for injured workers. An in-depth examination of the impact of mechanical LBP on the US workers’ compensation system, which varies from state to state, is beyond the subject of this article.
Many interesting perceptions about mechanical LBP have been noted:
In studies in which subjects had to answer self-assessment instruments, patients with insurance referrals had poorer self-assessment scores regardless of functional status.
Among different health care providers, patients rated care and communication, followed by competence, over efficacy of treatment.
Chiropractors often have been favored over internists and orthopedic surgeons on the basis of their “high touch” approach to treatment.
Orthopedic surgeons were found to be less restrictive with activities compared with family practitioners.
In a Dutch study, factors such as better health, better job satisfaction, status as breadwinner, lower age, and reporting of less pain were favorable prognosticators of return to work in individuals who had not been working for more than 3 months. The authors of the study believed that more focus was necessary on the psychosocial aspects of health behavior and job satisfaction.
Exercise was found to be more effective than usual primary care management
Medication Summary
Pharmacological interventions for the relief of low back pain (LBP) include acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), topical analgesics, muscle relaxants, opioids, corticosteroids, antidepressants, and anticonvulsants.
Acetaminophen remains one of the best first-line treatments of acute LBP. It is generally well tolerated, has few adverse effects or drug reactions with other medications, and is inexpensive. Acetaminophen is as effective as aspirin; however, overdoses can result in fatal hepatic injury. The maximum advised dose is 4 g/d.
NSAIDs are the most frequently prescribed analgesic medications for mechanical LBP worldwide. A review of the Cochrane Controlled Trials Registry found 51 randomized control trials (involving 6057 patients) comparing different NSAIDs for the treatment of acute mechanical LBP. [34] NSAIDs were found to be effective for short-term symptomatic relief. No specific type was shown to be clearly more effective than the others. Insufficient evidence was found for effective analgesic control in chronic LBP.
NSAIDs augmented with muscle relaxants are a standard medical prescription for LBP in the primary care setting. These agents should be prescribed on a scheduled basis, rather than as needed, for optimal analgesia. Patients on combined NSAIDs and muscle relaxants report reduction of symptoms at 1 week, which is less than when compared with either drug alone. The optimum combination of NSAIDs and muscle relaxants remains to be determined.
