Mechanical Low Back Pain

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.[3]

Numerous treatment guidelines have been written regarding the evaluation, treatment, and management of LBP.[4, 5] 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."[6]

At the beginning of the 21st century, 750 national and international organizations partnered to create the Bone and Joint Decade (2002-2011).[7] 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.[8, 9]

Lambeek et al assessed the efficacy of an integrated care program for chronic LBP against that of a more conventional care program, as a means of helping patients with this condition return to work. In the study, 66 patients received integrated care from a team made up of a clinical occupational physician, a physical therapist, an occupational therapist, and a medical specialist. Treatment included workplace intervention involving participatory ergonomics, as well as a graded activity program. Another 68 patients received the usual type of care for chronic back pain, administered by a medical specialist, general practitioner, occupational physician, and/or allied health care professionals.

Members of the integrated care group achieved a full, sustainable return to work in a median period of 88 days, while the same was accomplished in the conventional care group after a median 208 days. By 12-month follow-up, the integrated care group had experienced significantly greater improvement in functional status than had the conventional care patients. However, the investigators found no significant difference in pain reduction between the 2 groups at 12 months.[10]

Mechanical low back pain (LBP) generally results from an acute traumatic event, but it may also be caused by cumulative trauma.[1] 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.

Using data from the 2015 National Health Interview Survey, a study by Peng et al indicated that overweight and obesity are risk factors for low back pain (LBP). Compared with persons of normal weight, the adjusted odds ratios for LBP in persons with overweight or obesity were 1.21 and 1.55, respectively. However, the link between body mass index and LBP appeared to be impacted by sex and race/ethnicity. For example, the adjusted odds ratios for nonwhite men and women of normal weight were lower than the LBP risk for normal-weight white men.[11]

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.[12] 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.[13] 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.[14]

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.

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.

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.

A review study by Raastad et al of radiographic features in patients with LBP found that in community- and occupation-based studies, such pain was significantly associated with disk-space narrowing. LBP was also significantly linked with the presence of spondylolisthesis, but in occupation-based studies only. The review, which involved 28 studies (26,107 subjects total), also indicated that LBP has only a weak association with spondylosis and osteophytes and a nonsignificant association with endplate sclerosis.[15]

Research since the late 20th century suggests that chemical causes may play a role in the production of mechanical LBP. Components of the nucleus pulposus, most notably the enzyme phospholipase A2 (PLA2), have been identified in surgically removed herniated disk material. This PLA2 may act directly on neural tissue, or it may orchestrate a complex inflammatory response that manifests as LBP.

Glutamate, a neuroexcitatory transmitter, has been identified in degenerated disk proteoglycan and has been found to diffuse to the dorsal root ganglion (DRG) affecting glutamate receptors. Substance P (pain) is present in afferent neurons, including the DRG, and is released in response to noxious stimuli, such as vibration and mechanical compression of the nerve. Steady, cyclic, or vibratory loading induces laxity and creep in the viscoelastic structures of the spinal elements. This creep does not recover fully in the in vivo cat model, even when rest periods are equal in duration to the loading period.

The concept of a biomechanical degenerative spiral has an appealing quality and is gaining wider acceptance. This concept postulates the breakdown of the annular fibers allows PLA2 and glutamate, and possibly other as-yet unknown compounds, to leak into the epidural space and diffuse to the DRG. The weakened vertebra and disk segment become more susceptible to vibration and physical overload, resulting in compression of the DRG and stimulating release of substance P. Substance P, in turn, stimulates histamine and leukotriene release, leading to an altering of nerve impulse transmission. The neurons become sensitized further to mechanical stimulation, possibly causing ischemia, which attracts polymorphonuclear cells and monocytes to areas that facilitate further disk degeneration and produce more pain.

A study by Baumbauer et al indicated that a link exists between the COMT rs4680 genotype (GG) and the transition from acute to chronic LBP. In addition, an independent association with such transition seen with COMT expression.[16]

Frequency

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, as measured in years lived with disability (YLDs).[17, 18, 19]  A report by Hurwitz et al stated that in 2015, low back pain of over 3 months’ duration was experienced by more than 500 million people globally. That year, low back pain and neck pain together accounted for the fourth highest number of disability-adjusted life years (DALYs) worldwide, behind ischemic heart disease, cerebrovascular disease, and lower respiratory infection. The report concluded that the prevalence of low back pain and neck pain has risen since the late 20th century and will probably keep on increasing in response to aging populations.[20]

Estimates by numerous investigators indicate that at some point in their lives, 80% of all human beings experience LBP.

Mechanical LBP is more prevalent in countries with higher per capita income and where more liberal policies and adequate funds provide for compensation (eg, Germany, Sweden, Belgium).

In Sweden, the level of insurance benefits for disabling LBP is 100%, compared with a range of 0-80% in the United States. In 1987, the percentage of the work force placed on a sick list for diagnoses associated with back pain was 8% in Sweden versus 2% in the United States. In the same year, the average number of days of back-related absence from work per patient per year in Sweden was 40, versus 9 in the United States.

Mortality/Morbidity

While mechanical low back pain is not associated with mortality, morbidity in terms of lost productivity, use of medical services, and cost to society is staggering. Total workers' compensation costs for cases occurring in 1989 in the United States amounted to $11.4 billion, making it the most costly ailment for working-age adults. No evidence has been found to indicate that these costs are declining.

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.

Patients generally present with a history of an inciting event that produced immediate low back pain (LBP). The most commonly reported histories include the following:

• 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)[12]

• Involvement in a motor vehicle collision

• Falls

Commence the history by asking for the patient's age, hand dominance, and occupation. Also ask about the patient's current work status and last day he or she worked. If the back pain is the result of a work-related injury, ask the name of the employer and inquire how long the patient has worked for this particular employer. Sample questions are as follows:

• When did the current symptoms begin and what were you doing?

• What and where are your symptoms now? (A pain diagram is helpful for localizing the symptoms. The patient can draw on a figure and give the clinician an idea of the nature of the pain as neuropathic or nociceptive.)

• Rate the pain on a scale of 0 (none) to 10 (worst imaginable). This is a global pain rating that takes into account physiological and psychological aspects of the LBP.

• What makes the pain better (eg, sitting, standing, laying, medications, physical therapy)?

• What makes the pain worse (eg, sitting, standing, laying, medications, physical therapy)?

• What affect have these symptoms had on sleep, mood, work, activities of daily living, and/or social functioning?

Use open-ended questions to ascertain the maximum information about the patient's history. Establishing a rapport with the patient is essential to detect serious conditions, provide insights into the patient's concerns and expectations, and to achieve the optimum positive response to treatment.

In addition to the history of the present illness, the past medical history should be obtained to rule out infections (eg, septic arthritis), congenital abnormalities (eg, dysplasias, juvenile rheumatoid arthritis), metabolic disorders (eg, Paget disease), or previous traumatic causes (eg, athletic participation,[21] military service).

The review of systems is helpful for relating the current symptoms to any other body parts or systems. Patient self-reports of interruption in bowel or bladder function as well as immediate leg weakness and/or numbness should be "red flag" reminders to consider more serious causes of back pain such as a tumor, infection, or fracture and to direct management with a higher level of urgency and importance. Review of systems also should include a thorough medical history (including history of cancer, arthritis, infection, systemic disease that could increase susceptibility to infection, nocturnal pain, fever, drug use, depression, and symptoms suggestive of metabolic or metastatic disease). Ask for any history of headaches, peptic ulcer disease, prior cancer, or unexplained weight loss.

Assess for any history of previous treatments, such as the following:

• Surgery

• Medications: Obtain as complete a listing as possible, including reasons for discontinuation.

• Physical therapy

• Psychiatric or psychological therapy

Thoroughly screen for anxiety, depression, addiction, somatoform disorders, personality disorders, other prior psychiatric diagnoses, coping styles, and personality traits. Psychosocial factors (eg, depression, hypochondriasis, heavy alcohol consumption, tobacco use, menial work, poor job satisfaction, stressors at home and/or work) may accompany histories involving a work-related injury.

Assess the patient's vocational history. Look for consistency in the type of work and length of service with each employer since high school or college. Ask how many years the patient has been working for his or her current employer. Some cases have involved patients who have worked less than a week on a new job. Some work-related injuries are reported on a Monday or after a vacation. These are important dates for determining if the LBP was indeed work-related.

In a work-related LBP case, ask the patient about pending or planned litigation and related expectations.

Ask the patient what he or she thinks about the cause of the LBP.

Ask the patient what his or her goals are for the evaluation and treatment.

If the patient brought imaging study results (eg, plain radiographs, computed tomography [CT] scans, magnetic resonance imaging [MRI] scans), look for imaging evidence of herniated nucleus pulposus (seen in the images below), spinal stenosis, or other conditions associated with back pain.

An important initial 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 with a pointed finger.

Realize that much of the physical examination is subjective because a patient-generated response or interpretation to the examiner's questions or maneuvers is required. For example, sensory findings observed during the physical examination and reported symptoms in response to provocative testing are reliant on the patient's response and, hence, represent a somewhat subjective portion of the physical examination. A well-performed and well-documented physical examination, with consistent findings from one visit to the next, can yield important information that may be able to stand up to rigorous scrutiny by any involved third parties (eg, insurance company, attorney, workers' compensation judge). These physical examination findings would need to be put into the context of the patient's symptoms and diagnostic test results.

Equipment often used for the examination includes a stethoscope, goniometer, inclinometer, pinwheel or safety pin, tape measure, and reflex hammer.

Testing

Observe the patient walking into the office or examining room. Also, observe the patient's sitting posture and look for any signs of discomfort, during the history-gathering portion of the visit. The individual's standing posture and how the patient removes his/her shoes should be noted as well.

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 it is less than 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).

The neurologic examination should test 2 muscles and 1 reflex representing each lumbar root to accurately distinguish between focal neuropathy and root problems.

Measure leg lengths (anterior superior iliac spine to medial malleolus) if side-to-side discrepancy is suspected.

Using the inclinometer, measure forward, backward, and lateral bending. With the goniometer positioned in a horizontal plane over the axial skeleton (ie, over the head), measure trunk rotation.

The AMA Guides to the Evaluation of Permanent Impairment (5th edition) include reference tables for all motions, but these figures are not based on empiric data, only on consensus.[22] The ROM measurements in the AMA Guides do not correlate with disability and are not consistent within the document itself.

Palpate the entire spine to identify vertebral tenderness that may be a nonspecific finding of fracture or other cause of low back pain (LBP). Note any asymmetry, misalignment, or step-off between vertebral bodies. Remember also to palpate the sacroiliac joints.

Test for manual muscle strength in both lower extremities. The Medical Research Council rating is an ordinal scale used for this purpose (0 = absent strength, 1 = trace muscle movement, 2 = poor muscle strength [less than antigravity], 3 = fair muscle strength [antigravity strength through normal arc of motion], 4 = good strength, and 5 = normal strength).

Table 1. Functional Muscle Testing (Open Table in a new window)

 

Test for sensation and reflexes using 0-2 ordinal scale for pinprick sensation (0 = no sensation, 1 = diminished sensation, and 2 = normal sensation), and 0-4 ordinal scale to rate reflexes (0 = no reflex, 1 = hyporeflexic, 2 = normal reflex, 3 = hyperreflexic, and 4 = hyperreflexic with clonus).

Table 2. Dermatomal Sensory and Reflex Testing (Open Table in a new window)

Clinical tests for signs of sciatic nerve tension are as follows:

• Supine straight leg raising (SLR) test - Reproduction of pain caused by elevation of the contralateral limb raises the probability of a disk herniation to 98%. Remember that the SLR test result can be negative in persons with spinal stenosis.

• Sitting SLR (knee extension) test (for lower roots) - The patient should sit on the table edge with both hips and knees flexed at 90° and extend the knee slowly. This maneuver stretches the nerve roots as much as a moderate degree of supine SLR. The SLR test result, if positive, reproduces symptoms of sciatica with pain that radiates below the knee.

• The prone SLR test (also called the reverse SLR test or the femoral nerve stretch test) assesses the upper lumbar roots, a less common site of radiculopathy worth remembering.

Nonphysiologic testing (Waddell signs) should be performed. The presence of 3 or more positive findings out of the 5 types may be clinically significant in terms of psychosocial issues or poor surgical outcome. Isolated positive signs are of limited value.

Nonorganic tenderness consists of the following:

• Superficial - Skin tenderness to light pinch over a wide area of lumbar surface

• Nonanatomic - Deep tenderness over a wide area, often extending cephalad to the thoracic spine or caudad to the sacrum

Simulation tests give the patient the impression that a particular examination is being conducted, including the following:

• Axial loading - Vertical loading over the patient's head while he or she is standing, producing LBP

• Rotation - Back pain when the shoulders and pelvis are rotated passively in the same plane with the feet together

Distraction tests indicate a positive finding when the patient's attention is distracted.

• SLR - Observing an improvement of 30-40° when the patient is distracted, compared with formal testing.

• Flip test - The patient is seated with the legs dangling over the examination table. Instruct the patient to steady himself or herself by holding the edge of the table. When the affected leg is flipped up quickly, the patient falls back and lets go, placing both hands behind him or her on the table.

Regional disturbances that do not correlate with anatomy include the following:

• Weakness - Cogwheeling (giving way) of many muscle groups upon manual muscle testing of strength

• Sensory - Diminished light touch or pinprick sensation in a stocking pattern, rather than a dermatomal pattern, in an individual who is not diabetic

• Nonanatomic sensory loss

Overreaction during the examination may be observed in several manifestations (eg, disproportionate verbalization, facial grimacing, muscle tension and tremor, collapsing, sweating). Care must be taken to account for cultural variations.

In addition, evaluate the patient's function. Observe ROM and flexibility, ability to dress and undress, and ability to rise from a chair or the examination table.

If the history elicits reports of fever, night sweats, and chills that might suggest other causes for the low back pain, then, at a minimum, obtain a CBC count, erythrocyte sedimentation rate, and urinalysis to rule out cancer or infection. Serum and urine electrophoresis studies may help to rule out multiple myeloma at an early stage when radiographic imaging studies appear negative or inconclusive.

The association between symptoms of mechanical low back pain (LBP) and imaging results is weak. Ordering of imaging studies should be limited to patients with clinical findings suggestive of systemic disease (eg, fever, weight loss without explanation, patients older than 50 y, alcohol use, or intravenous drug abuse) or trauma.

In the absence of any findings from the neurologic examination and no evidence of infection or cancer, imaging studies are not clinically helpful in the first 4 weeks of symptoms. The Quebec Task Force of Spinal Disorders (QTFSD) suggests that early radiographs are necessary only if the patient has neurologic deficits, fever, trauma, age older than 50 years or younger than 20 years, or signs of neoplasm. Anteroposterior and lateral views should be used on plain films unless spondylolysis is suggested, in which case oblique views are needed.

Persistent mechanical LBP may require additional imaging studies, including CT scanning, diskography, and 3-phase bone scanning. Sensitivity refers to the ability of the test or study to show that a disorder is present. Specificity refers to the ability of the test or study to rule in a specific disorder. The higher the number [0 to 1], the more sensitive or specific the test or study.

CT scanning has a sensitivity and specificity of 0.92 and 0.88, respectively, for a herniated disk.

MRI is superior to CT scanning for detection of many conditions because it presents soft tissue detail and multiple planar points of view; it should be used if infection, cancer, or persistent neurologic deficit is strongly suggested. See images below.

Diskography has a sensitivity and specificity of 0.83 and 0.78, respectively, for a herniated disk. This test should be interpreted in the context of data on pain reproduction.

A 3-phase bone scanning may be helpful if infection, metastatic cancer, or pathological fracture is suggested.

Thermography has no known role in the evaluation of mechanical LBP.

Electrodiagnostic studies such as electromyography (EMG) and nerve conduction studies (NCS) can be very helpful in the evaluation of neurologic symptoms and/or neurologic deficits seen during the physical examination.

In the context of patients with low back pain (LBP) and neurologic symptoms/signs in the lower limb(s), EMG/NCS can objectively assess whether those symptoms/signs are due to lumbosacral radiculopathy versus peripheral polyneuropathy, myopathy, or peripheral nerve entrapment, among other conditions.

Further, EMG/NCS can often help identify which specific nerve root is involved in a given radiculopathy, which can be extremely helpful for correlation with any abnormal lumbosacral imaging study results (especially when the MRI shows multilevel abnormalities, while the nerve root compromise may be occurring in only 1 specific level). Identifying the specific nerve root involved can help ensure that any spinal injections or eventual surgery are performed at the appropriate level or site within the lumbar spine.

EMG/NCS is considered to have a relatively high degree of sensitivity for detecting radiculopathy, particularly with use of the needle EMG portion of the testing, when performed by an appropriately skilled physician. Further, because a patient is unable to voluntarily influence the appearance of abnormal EMG/NCS findings, the testing can be helpful in providing objective evidence of nerve pathology (or lack of evidence for such nerve pathology) in cases in which symptom magnification or malingering is suspected.

Many of the abnormal EMG/NCS findings take a couple of weeks to appear after an acute injury; hence, many electromyographers wait 2-4 weeks before performing the testing.

Selective nerve root blocks and intradiskal injections are 2 diagnostic and therapeutic procedures for identifying the location of a possible pain generator.[8, 9] These interventions depend on the patient's self-report of pain during or after the procedure. Some clinicians videotape the patient's reaction to the injection to correlate the patient's response (subjective) with the physical response (objective).

Anatomic studies of autopsy tissues taken from individuals aged in their 20s reveal a superficial annulus fibrosus ligament over the ventral surface of the L5 intervertebral disk. This ligament is completely separate from the overlying anterior longitudinal ligament and the intervertebral disk. The fibers are vertically oriented.

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.

• Acupuncture appears to produce functional improvement in the immediate post-treatment period but does not seem to bring about a clinically significant reduction in pain.[23]

Physical Therapy

The treatment program for mechanical low back pain (LBP) must have specific functional goals and can be outlined in the following 6 steps:

• Control of pain and the inflammatory process - Pain treatment should be initiated early and efficiently to gain control. Ice, transcutaneous electrical nerve stimulation (TENS), and relative rest may help with controlling the pain and the inflammatory process. Excessive bedrest, however, may be detrimental by leading to lumbar segment motion, loss of muscle strength, and general deconditioning with blunting of motivation.

• Restoration of joint ROM and soft tissue extensibility - Extension exercises may reduce neural tension. Flexion exercises reduce articular weight-bearing stress to the facet joints and stretch the dorsolumbar fascia. The use of ultrasound therapy may improve collagen extensibility.

• Improvement of muscular strength and endurance - Exercise training can begin after the patient has passed successfully through the pain control phase. The key is to attain adequate musculoligamentous control of lumbar spine forces to minimize the risk of repetitive injury to the intervertebral disks, facet joints, and surrounding structures. Start with isometrics, then progress to isotonic exercises with effort directed at concentric strengthening.

• Coordination retraining - Dynamic exercise in a structured training program maximizes coordinated muscle group activities that lead to postural control and the fusion of muscle control with spine stability.

• Improvement of general cardiovascular condition - Patients are encouraged to remain active and to initiate brisk walking programs, aquatic activities, or use of stationary bicycles/stair steppers. These activities can increase endorphin levels, promoting a sense of well-being, and allow the patient to perform at a higher level of function before perceiving pain.

• Maintenance exercise programs - A home program is developed within the tolerance and ability of the patient in order to encourage continued exercise after discharge from physical therapy.

Sertpoyraz et al compared isokinetic and standard exercise programs for chronic LBP.[24] Pain, mobility, disability, psychological status, and muscle strength were measured. Forty patients were randomly assigned to a program that took place in an outpatient rehabilitation clinic. No statistically significant difference was found between the 2 programs with regard to their effect in the treatment of low back pain.

The main goal of physical therapy in persons with acute back pain is not to increase strength but to achieve adequate pain control. No benefit has been demonstrated for strengthening exercises in persons with acute back pain. Exercise should begin with extension exercises in the prone position after lateral trunk shifts and then progress, as tolerated, to prone lying with support. Flexion exercises can be performed only if the patient has no acute dural tension.[25, 26]

The spine should be stabilized using strengthening of segmental muscles followed by the prime movers of the spine (ie, latissimus dorsi, abdominals, erector spinae). Muscle groups should be strengthened in a neutral position to decrease tension on ligaments and joints; this position allows balanced segmental forces between the disks and the zygapophyseal joints and maximizes functional stability with axial loading.

Physical therapy programs should also include positioning the patient to maximize comfort. Loosening of the hamstrings, glutei, gastrocnemius/soleus group, tensor fascia latae, quadriceps group, and hip flexors also contributes to reduction of LBP and effective conditioning.

In a 2004 multicenter randomized trial, patients who were trained in exercises that matched their directional preference (DP) were more likely to achieve immediate, lasting improvement in pain compared with patients who received nondirectional treatment or opposite directional treatment.[27] Patients using DP exercises were found to have a 3-fold decrease in medication usage. The idea of patient-specific exercises in managing LBP is recognized as controversial by the authors. Using DP to guide patients may improve outcomes in pain, function, and treatment satisfaction.

A randomized, controlled trial by Michaelson et al found no significant difference in outcomes for patients with mechanical LBP whether they underwent therapy with high-load lifting exercise or low-load motor control exercise, with 50-80% of subjects reporting reduced perceived pain intensity and disability at short- and long-term follow-up (2-24 mo). The study included 70 patients.[28]

Jüni et al found that the addition of spinal manipulative therapy to standard care is unlikely to result in relevant early pain reduction in patients with acute LBP.[29] In a randomized trial involving 104 patients with acute LBP, pain reduction during days 1-14 and at 6 months were similar (P = .13) in patients who received spinal manipulative therapy plus standard care—consisting of general advice and acetaminophen, diclofenac, or dihydrocodeine as needed—and those who received only standard care. Small initial differences in analgesic use diminished over time.

Hill et al in a study from 2011 tested stratified primary care with nonstratified current best practice to determine which was clinically more effective and cost-effective for back pain. Patients with back pain (N=851) were placed in the intervention (n=568) and control groups (n=283). The results indicate that after 12 months, the patients who received stratified care showed an overall increase in their health, as well as healthcare cost savings compared with the control group.[30]

Yoga can also be an effective treatment for low back pain, a study by Tilbrook et al has determined. In a randomized, controlled study, 313 patients for a 12-week period either attended yoga classes (n=156) or were given the usual care for chronic low back pain (n=157). After 3, 6, and 12 months, the yoga group demonstrated better back function compared with the usual care group.[31]

A randomized trial of 228 patients compared yoga (n=92), stretching (n=91), and a self-care book (n=45) for alleviation of chronic LBP. The results indicated that stretching classes were the best treatment option in improving function and reducing chronic LBP for at least several months, followed by yoga classes, and then the self-care book. Outcomes were assessed at baseline, 6, 12, and 26 weeks.[32]

A prospective study by Ben-Ami et al of 189 patients with chronic LBP found that those who underwent a physical therapy program focused on dealing with obstacles to physical activity (an enhanced transtheoretical model intervention [ETMI]), including low self-efficacy and fear avoidance, in order to increase recreational physical activity, experienced better reduction in long-term disability than did patients who underwent usual physical therapy. The investigators determined that at 12-month follow-up, patients who underwent the ETMI had significantly better results with regard to worst pain, physical activity, and physical health.[33]

A study by Bade et al indicated that in patients with mechanical LBP, treatment of not just the lumbar spine but of the hips as well, though manual therapy and exercise, produces better results than treatment of the lumbar spine alone. At 2 weeks after treatment began, the investigators found that the global rating of change (GRoC) scale score and patient satisfaction were better in the lumbar spine/hips group, while at discharge, significantly better results for this group were seen in the Modified Oswestry Disability Index, the numeric pain rating scale, the GRoC scale score, and patient satisfaction.[34]

A prospective study by Thomson et al indicated that restorative neurostimulation can bring improvements in pain and disability in patients with chronic mechanical LBP. Patients were treated with an implantable device that stimulated the L2 medial branch of the dorsal ramus. The investigators found that at 2-year follow-up, 57% of patients had experienced pain reduction of greater than 50%, while in 51.4% of patients, the disability score had improved by more than 15 points.[35]

Surgical interventions for mechanical low back pain (LBP) are the last choice for treatment. Diskectomies are performed in the United States at a rate proportional to the number of spine surgeons in the community. The US rate of surgeries is twice that of Europe, Canada, and Australia and is 5 times the rate in the United Kingdom. Better results occur with open excisions compared with percutaneous diskectomies. Results are best when no workers' compensation or litigation is involved.[36, 37]

Medical Care

A prospective, randomized, controlled study by Soneji et al indicated that in patients with chronic mechanical LBP caused by sacroiliac joint arthritis, the use of fluoroscopy alone is as effective as the employment of ultrasonography with fluoroscopic confirmation in guiding local anesthetic and steroid injections to the sacroiliac joint. The study, which involved 40 patients, found that pain scores did not differ significantly between the fluoroscopy and ultrasonography groups at 24-hour, 72-hour, 1-week, 1-month, and 3-month follow-up, with both groups showing significant pain reduction at 1 month.[38]

Guidelines

Evidence-based clinical practices on selected rehabilitation interventions for low back pain (LBP) have focused on the timing of interventions.

• Acute LBP is defined as pain that does not radiate below the knees with current symptoms that have been present 4-6 weeks or less.

• Subacute LBP is defined as pain that does not radiate below the knees with current symptoms that have been present 4-12 weeks from onset.

• Chronic LBP is defined as pain that does not radiate below the knees with current symptoms that have been present greater than 12 weeks.

• The Philadelphia Panel evaluated the literature on the treatment of LBP and assigned Grades of Recommendation based on the clinical importance of the studies, statistical significance of the findings, and the study design.[5] Randomized control trials with statistically significant findings were assigned an A grade. Any study design without clinically significant findings but thought to have been worth performing was assigned a D grade. Grades of Evidence were assigned to the various studies. The highest grades were I for randomized control trials and III for the opinions of respected authorities.

  • For LBP of less than 4 weeks duration, the Philadelphia Panel found poor evidence (grade C) to include or exclude therapeutic exercises, traction, ultrasonography, or TENS. Return to work was strongly encouraged.

  • For LBP of 4-12 weeks duration, the Philadelphia Panel found good evidence for the inclusion of therapeutic exercise and manual traction.

  • For LBP of greater than 12 weeks' duration, the Philadelphia Panel found good evidence for the inclusion of therapeutic exercises, therapeutic ultrasonography, and electromyographic biofeedback. These treatments were positive interventions for achieving adequate pain control, increasing functional activities of daily living, and promoting return to work.

• Evidence-based clinical practice guidelines from the American Pain Society (APS) for patients with chronic low back pain describe the use of interventional diagnostic tests and therapies, surgeries, and interdisciplinary rehabilitation.[39]

  • Practice guidelines for nonradicular pain

    • Interdisciplinary rehabilitation that emphasizes cognitive-behavioral approaches should be considered for patients who fail to respond to usual interventions.

    • Provocative diskography (in which material is injected into a disk nucleus to reproduce the patient's typical pain) is not recommended.

    • Facet joint corticosteroid injection, prolotherapy (stimulation of an inflammatory response through repeated injections of irritant material), and intradiskal corticosteroid injection are not recommended.

    • Degenerative spinal changes and persistent, disabling symptoms should lead to discussion and shared decision-making regarding surgery or interdisciplinary rehabilitation. (The evidence is insufficient to weigh the risks and benefits of vertebral disk replacement in these patients.)

  • Practice guidelines for persistent radiculopathy

    • For patients with herniated disks, the use of epidural steroid injection should be discussed.[40]

    • For patients with herniated disks and disabling leg pain from spinal stenosis, surgical options should be discussed.

    • For patients with persistent pain after surgery, the risks and benefits of spinal cord stimulation should be discussed.

Pharmacologic 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.[41] 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.

Topically applied lidocaine patches (Lidoderm 5% patch) have provided a reduction in pain intensity and pain relief in clinical trials of patients with acute pain.

Opioid medications are mainstays for short-term treatment of severe pain. Their role in the long-term care of patients with mechanical LBP is the subject of intense investigations. Transdermal opioid (fentanyl) has been shown to compare favorably to oral long-acting opioids. Concerns about drug diversion and abuse continue to cloud the benefits of long-term opioid use for LBP.

Corticosteroids may play a role in the treatment of mechanical LBP with acute radiculopathic features of radiating pain down one or both legs.

Antidepressants are thought to be effective when a component of depression is accompanying the mechanical LBP. Antidepressants may contribute to improving the disruption in sleep that patients frequently mention as a part of the constellation of symptoms resulting from LBP.

The basic mechanism of anticonvulsants is to stabilize neural membranes. This concept has been used to support the use of anticonvulsants for adjunct analgesia suspected to come from neuropathic causes.

Botulinum toxin type A has been investigated for pain relief in several small studies. The toxin temporarily paralyzes the lumbar muscles, which may be creating spasms that contribute to the generation of LBP.

Clinicians have found that long-acting oral opioids can be rotated periodically (eg q6-12mo) to maintain effectiveness. The molecular structures of these compounds may be sufficiently different to opioid receptors to counter the affects of diminished and down-regulation of receptors to chronic opioid exposure.

Pharmaceutical companies are exploring various combinations of NSAIDs/opioids, extended-release formulations, and drug delivery (eg topical, mucosal) in an effort to achieve safe and effective pain control.

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma or have sustained injuries. The FDA has cleared duloxetine to treat chronic musculoskeletal pain.[42]

Acetaminophen (Tylenol, Feverall, Tempra)

DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

Duloxetine (Cymbalta)

Potent inhibitor of neuronal serotonin and norepinephrine reuptake. Indicated for chronic musculoskeletal pain, including discomfort from osteoarthritis and chronic lower back pain.

Class Summary

Have analgesic, anti-inflammatory, and antipyretic activities.[41] Mechanism of action is not known, but they may inhibit COX activity and prostaglandin synthesis. Other mechanisms may also exist, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions.

Aspirin (Anacin, Ascriptin)

Effective in most mechanical LBP cases. Irreversibly inhibits platelet function, leading to prolonged bleeding times.

Naprosyn (Naproxen, Naprelan, Naprosyn)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing activity of COX, which results in a decrease of prostaglandin synthesis.

Class Summary

Although increased cost can be a negative factor, the incidence of costly and potentially fatal GI bleeding is clearly less with COX-2 inhibitors than with traditional NSAIDs. Ongoing analysis of cost avoidance of GI bleeds will further define the populations that will find COX-2 inhibitors the most beneficial.

Celecoxib (Celebrex)

Inhibits primarily COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited, thus GI toxicity may be decreased. Seek lowest dose of celecoxib for each patient.

Class Summary

Mechanism of action is not fully understood.

Cyclobenzaprine (Flexeril)

Skeletal muscle relaxant that acts centrally and reduces motor activity of tonic somatic origins, influencing alpha and gamma motor neurons.

Structurally related to TCAs and thus carries some of their same liabilities. Given in combination with an NSAID (similar to carisoprodol).

Orphenadrine (Norflex)

While exact mode of action not well understood, has shown clinical effectiveness in muscular injury. Effectiveness may be related to analgesic properties. May have atropinelike effects and analgesic properties.

Carisoprodol (Soma)

Short-acting medication that may have depressant effects at spinal cord level. Often given in combination with an NSAID.

Class Summary

Useful only for extremely severe pain. Can be administered by injection.

Oxycodone (OxyContin)

Indicated for relief of moderate to severe pain. Use of this medication should be discussed with the prescribing physician due to numerous concerns, including with regard to addiction, abuse, diversion, and overdosing.

See the list below:

• The proper application of physical therapy, analgesic medications, and selected injections (when warranted) can produce a positive impact on the functional outcome of mechanical low back pain (LBP).

• Careful and complete history gathering, objective physical examinations, and clearly prescribed therapeutic interventions are fundamental in the management of mechanical LBP.

• Patients may need regular follow-up and careful monitoring to ensure a positive outcome. Structured daily activity is crucial to encourage patients to realize that their efforts result in a positive outcome.

• The most successful management of mechanical LBP comes from an interdisciplinary team approach of physicians, therapists, counselors, and case managers.

• Sometimes, the physician needs to return to the history when if a puzzling clinical presentation that cannot be resolved.

• Ensuring care between the physicians and therapists is coordinated, evidence-based medical practices are being used, and certain published guidelines are being considered may help achieve the optimum treatment for LBP patients.

See the list below:

• Mechanical low back pain (LBP) generally is treated in an outpatient setting. Inpatient care may be appropriate in some cases when compelling evidence of neurological deficits is present along with an accompanying history of infection, malignancy, and/or trauma. The initial medical workup should be performed in the general acute hospital setting.

  • Patients who are elderly or severely disabled with no social support may need to be admitted into a medical setting for diagnostic studies and therapeutic interventions.

  • A comprehensive interdisciplinary approach combines the medical management of the pain with the functional restoration of motion and activities of daily living that is achieved through physical and occupational therapy.

  • More varied modalities can be used in the rehabilitation unit (eg, aquatic therapy, other physical modalities), as can counseling for the patient and his or her family. Psychological counseling may be more readily available in the rehabilitation unit, compared with the general medical or surgical unit.

See the list below:

• The most commonly prescribed medications for mechanical low back pain (LBP) are NSAIDs, muscle relaxants, opioid and nonopioid analgesics, and antidepressants.

  • NSAIDs provide satisfactory analgesic relief for most cases of mechanical LBP. NSAIDs are very easy to obtain in prescribed formulations and as over-the-counter preparations.

  • Muscle relaxants, in combination with the NSAIDs, may provide symptomatic relief to the low back musculature and promote more freedom of movement.

  • Opioid medications generally are not used as first-line treatments for mechanical LBP.

  • Nonopioid medications are being combined with NSAIDs to achieve adequate pain relief without the adverse effects of opioid medications.

  • Antidepressants are helpful adjuncts to the bio-psycho-social effects of chronic LBP.

See the list below:

• Patients with mechanical low back pain (LBP) may present to their family physicians or to the emergency department of a hospital or clinic. After determining the patient has no life-threatening cause for the mechanical LBP (eg, tumor on the spine, fracture of the axial spine), consideration should be given to transferring the patient to an appropriate outpatient care facility or to an inpatient rehabilitation unit for pain management, reconditioning of muscles, and preventive treatment.

See the list below:

• Prevention of most cases of mechanical low back pain (LBP) can be achieved using good biomechanical principles when performing heavy manual labor. Deterrence and prevention information is mostly anecdotal and depends on education and raising the awareness levels of individuals at risk for developing mechanical LBP.

See the list below:

• Complex social, legal, and economic issues tend to produce most of the complications surrounding mechanical low back pain (LBP). A full account of these issues is beyond the scope of this article. The following complicating factors have been associated with extended care of LBP and should be viewed as "yellow flags" to help the physician explore other causes to the chronic spinal condition being presented:

  • Trauma

  • Greater than 4 separate episodes of LBP

  • Sciatica defined as pain extending below the knees

  • Skeletal anomalies

  • Heavy smoking

  • Multilevel degenerative joint disease

  • Job dissatisfaction

  • Job disability in previous 12 months

  • Psychological distress and abnormal illness behavior (eg, positive Waddell signs, pain consistently rated 9/10, pain avoidance behavior, symptom proliferation, total body pain, collapsing or inability to move)

• In an informal survey of chiropractors who were asked to rate the top 10 "back-breaking jobs," the number 1 job was heavy truck driving. Following, in no particular order, are the next 9 jobs:

  • Construction worker

  • Landscaper

  • Police officer (due to long hours sitting in a car then having to respond to a call for help)

  • Farmer (because self-employment, tend to respond rapidly to pain management interventions)

  • Roofers (often in awkward, bending positions for long periods)

  • Firefighters and emergency medical technicians

  • Delivery drivers

  • Nursing home workers

  • Auto mechanics

The prognosis is good for recovery from mechanical low back pain (LBP). At 1 month, 35% of patients can be expected to recover; at 3 months, 85% have recovered; and at 6 months, 95% have recovered.

Failure of a patient to recover should lead the clinician into a more thorough and extensive search into the cause of the back pain, including the possibility of recurrent back injuries.

Recurrence at 1 year is 62%. At 2 years, 80% of patients have had 1 or more recurrences. The question remains whether this is the inevitable result of natural aging, continued pathologic processes, somatization, or a combination of all of these. Clearly, much more research is required.

A prospective cohort study by Mehling et al reviewed outcome measures for recovery in primary-care patients with recent-onset acute LBP. Since a consensus does not exist about outcome definitions or how to identify when patients have failed to recover from an episode of LBP, the authors suggest that a combination of ratings from perceived recovery scales along with pain and disability measures be used as a highly accurate way to identify recovery.[43]

A study by Imagama et al indicated that in patients with chronic LBP, factors that negatively impact the outcome of pharmacologic therapy for the condition include neuropathic pain at baseline, Tramacet use at baseline, use of weak opioids at baseline, older age, lengthy disease duration, a history of spinal surgery, and smoking.[44]

See the list below:

• Patient education should begin with reassurance and a management plan, even though a precise pathoanatomic diagnosis may not be possible.

• The importance of educating patients to understand that uncomplicated mechanical low back pain (LBP) has a natural course of recovery cannot be overemphasized.

• One consistent finding from a review of the literature is that people who are depressed, have poor job satisfaction, and can receive compensation as long as their backs hurt have an increased prevalence of mechanical LBP that develops into chronic disability.

• Deal with external factors that influence recovery, including anxiety, and increase the patient's understanding of the expectations of key players (eg, family, physician, employer) compared with his or her own goals.

• Posture, reconditioning, proper nutrition, and stress management also should be addressed.

• For patient education resources, see the patient education articles Low Back Pain, Sprains and Strains, and Pain Medications.