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Spinal Manipulative Therapy for Low Back Pain

Swenson, Rand DC, MD, PhD; Haldeman, Scott DC, MD, PhD, FRCPC

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Journal of the American Academy of Orthopaedic Surgeons: July 2003 - Volume 11 - Issue 4 - p 228-237
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Abstract

Spinal manipulative therapy (SMT) is one of the oldest therapeutic procedures offered to patients with lumbar spine pain. Although it has been used for more than 2,000 years, until recently there has been little scientific evidence comparing its mode of action and effectiveness with those of other techniques. Interest in and use of complementary and alternative therapies increased in the United States during the last decade of the 20th century.1 Patients with low back pain often seek care from clinicians who offer relaxation therapy, yoga, nutritional supplements, herbal therapy, massage, acupuncture, and spinal manipulation.

Spinal manipulation is the most common and widely recognized of the complementary and alternative therapies used to manage low back pain. In fact, it is so commonplace that there is now debate about whether it should be considered part of mainstream health care. Chiropractors, who provide the greatest percentage of manipulative treatments,2,3 are now licensed in all states and are recognized as primary contact health care clinicians; in addition, their services are covered by most health insurance systems, including Workers' Compensation, Medicare, and the Military Health System. However, spinal manipulation is not practiced exclusively by chiropractors. Some osteopathic physicians, physical therapists, and medical physicians are providing and specializing in SMT. The exact utilization rate of spinal manipulation in the United States is not known, but it is estimated that >90% of spinal manipulations in the United States are done by chiropractors.3 Although many chiropractors also include other physical modalities, nutritional advice, and rehabilitation in their practices, most chiropractic visits include SMT. Approximately 30% of patients with low back pain use the services of chiropractors, with additional patients receiving SMT from other health care practitioners.2 Shekelle and Brook4 studied insurance industry data and reported that 7.5% of patients in their population group used chiropractic services each year and that there was an average of 41 visits per 100 person-years.

The increased volume of research about the effectiveness and mechanisms of action of SMT have led to the inclusion of SMT on a very short list of national guidelines for managing acute low back pain (eg, those developed by the Agency for Healthcare Research and Quality5 in the United States and similar guidelines developed in Great Britain and Denmark). Many patients under the care of practitioners of conventional medical techniques (eg, orthopaedic surgeons, neurosurgeons, physiatrists) have already undergone manipulation or will consider spinal manipulation, especially if more commonly practiced medical procedures prove to be ineffective. Therefore, it is important for any physician who treats patients with back pain to be knowledgeable enough to advise patients about SMT and to consider whether there is a role for such treatment in selected patients.

Spinal Manipulation

Many treatment methods are encompassed within SMT. These techniques can be divided into three broad categories: therapeutic massage, mobilization, and manipulative procedures (or adjustments). Massage includes manual procedures applied to the spinal soft tissues without causing joint movement, such as deep tissue massage, acupressure, muscle stimulation, and relaxation methods. Mobilization generally refers to procedures that exert stretching, traction, or pressure on the spine within or at the limit of active range of motion.6 Mobilization procedures typically involve slow, occasionally rhythmic stressing of the joint, ligaments, and muscles. They usually consist of passive force exerted by the clinician on the joint but may require active contraction of specific muscles by the patient to assist in the motion. Massage and mobilization often are used in preparation for spinal manipulation as a way of reducing the force needed to do the manipulation and to relax the patient.

Spinal manipulation usually requires application of a quick, highvelocity, short-amplitude force, either directly or indirectly, to the spine.6 Manipulative forces can be applied with the patient lying either on his or her side or prone. Most of these techniques involve so-called short levers directed at the vertebral processes (eg, spinous, transverse, mammillary, articular) to apply force to a specific spinal segment. So-called long lever techniques consist of force applied to an extremity (eg, arm, shoulder, hip, leg) to move the spine indirectly. Spinal manipulative procedures also may involve traction or a mobilizing force at the end of the physiologic joint range of motion, followed by a short-amplitude impulse to move the joint into the paraphysiologic range, beyond the passive range of motion but short of the point of anatomic disruption of the joint (Fig. 1). The typical forces and movements produced by such types of manipulation have been characterized in studies of volunteers.7 The movement is often accompanied by an audible sound that may be attributable to joint cavitation,8 which is the release of tissue gas (probably nitrogen) into the joint space as the result of a vacuum created by the manipulative thrust. This audible sign indicates that there has been motion in the joint. However, many manipulative practitioners do not consider an audible release essential to obtain a good manipulative response.

Figure 1
Figure 1:
Mobilization and manipulation take the spine beyond the active range of motion (Zone A). Ligaments and muscles resist motion beyond that point; articular mobilization passively stretches them into Zone B, although it may be actively assisted by the patient. Manipulation involves bringing the joint beyond this passive range of motion into a paraphysiologic range of motion (Zone C). Often there is cavitation of the joint being manipulated. Motion beyond that point may cause injury to the structures supporting the joint.

A common spinal manipulative procedure is the so-called hold-thrust adjustment, in which the force is maintained briefly before and after the application of the impulse. The recoil technique involves an impulse from a neutral position followed by an immediate termination of contact. In several techniques, very low force is applied in precise directions to vertebral structures, under the theory that the more specific the thrust, the less force necessary. Acupressure and soft-tissue massage may be done in preparation for manipulation or as the sole method of treatment. In addition, several mechanical devices, such as the handheld, spring-loaded Activator (Fig. 2), have been developed to deliver force directly to the spine with or without manual guidance. It remains to be determined whether the mechanical and clinical effects produced by these instruments are similar to those of the manual techniques.9

Figure 2
Figure 2:
Manipulation with a handheld device (Activator; Activator Methods International, Phoenix, AZ) designed to deliver force to the tissue of the back.

Theoretic Basis for Symptom Relief

The theoretic basis for SMT has evolved with increased understanding of spinal pathology, spinal biomechanics, and pain physiology. Initially, the manipulable lesion (osteopathic lesion or subluxation in chiropractic terminology) was considered a bone out of place impacting either the vascular structures or spinal nerve roots.10 Most manipulative practitioners and all chiropractic schools have broadened this concept to encompass current theories of spinal pathology that incorporate concepts of abnormal spinal biomechanics and include neurophysiologic theories about reflex function and pain physiology.11

The most common theory of the manipulable lesion is that a vertebral unit can display abnormal motion or become fixated (ie, mobility can be restricted within the normal physiologic range of joint motion). Additionally, it is thought that biomechanical changes are often associated with pain and abnormal spinal reflex function, including muscle spasms and autonomic nervous system responses. The manipulation is thought to have a direct effect on muscles and joints as well as an indirect effect on the nervous system. Limited experimental and clinical evidence supports this theory. Magnetic resonance imaging studies have indicated a direct effect on spinal joints consistent with reports describing increased spinal range of motion after spinal manipulation.12 Spinal manipulation also is accompanied by a reflex contraction of paraspinal musculature.13 Whether this is of therapeutic benefit and whether these reflex responses produce long-term changes in muscle tone or muscle spasm are unknown.

Recent neurophysiologic research has focused on possible effects of SMT on the central nervous system.11 Altered pain thresholds have been reported after SMT, possibly related to activation of endogenous pain-suppression mechanisms. In addition, decreased pain response after lumbar manipulation has been associated with abnormal somatosensory-evoked potentials from paraspinal musculature of patients with low back pain, suggesting a central effect on sensory processing.14 Activation of zygapophyseal joint receptors in rats is capable of markedly attenuating the reflex response in paraspinal muscles to noxious stimulation of nerves in the intervertebral disk,15 which suggests interaction between spinal joint receptors and the processing mechanisms for spinal pain reflexes, at least in animals. Suter et al16 investigated the effect of manipulation of the sacroiliac joint on the degree of quadriceps muscle inhibition produced by knee joint pathology. They showed that manipulation of the sacroiliac joint decreased the inhibitory effect, suggesting interaction between manipulation and the inhibition of voluntary activity produced by pain. Despite experimental observations, however, the underlying mechanisms proposed to explain the therapeutic effects of SMT remain poorly understood and require further investigation.

Clinical Trials

Many patients with uncomplicated low back pain do not have clear and quantifiable underlying pathophysiology, which has largely prevented the use of physiologic outcome measures in studies of back pain treatment. For this reason, studies of the therapeutic efficacy of most treatment approaches to low back pain have tended to be empiric, relying on clinical outcome measures such as pain scores, functional capacity, patient satisfaction, time lost from work, and cost (mostly from insurance and Workers' Compensation data). Many of these researchers have attempted to compare chiropractic with conventional medical treatment, while others have compared spinal manipulation with other nonsurgical interventions or placebo treatments. Although most patients treated by chiropractors receive spinal manipulation, chiropractic treatment is rarely limited to this modality, and caution must be exercised when extrapolating from trials of chiropractic care. For example, studies of patient satisfaction have been very favorable to chiropractic treatment, but that may have more to do with doctor-patient interaction than with SMT.17 Although comparison studies of Workers' Compensation18 and private health insurance19 data have mostly shown similar or lower costs for patients treated by chiropractors, this may reflect a difference in the population that seeks alternative providers.

The most widely accepted model for overcoming the problem of different patient populations is the randomized clinical trial. Forty-four randomized clinical trials evaluating the efficacy of spinal manipulation in patients with low back pain have been published, and there are more than 50 reviews of these trials, each using different criteria to determine their value. There are even systematic studies that rate the quality of these clinical trial reviews.3,20-28

Many of the published clinical trials are of relatively low quality, often involving small numbers of patients, differing outcome measures, short follow-up periods, heterogeneous study populations, a range of methods of manipulation or manual therapy, and varying degrees of blinding of patients and assessors. It is extremely difficult to blind patients in randomized controlled trials of physical interventions such as spinal manipulation and, therefore, to develop appropriate placebo controls. Many researchers have avoided placebo and instead have tried to use more pragmatic approaches, such as examining and comparing the outcomes of two or more common clinical procedures, one of which is manipulation or manual therapy. However, the clinical value of many of the treatments against which manipulation can be compared is mostly unknown or has minimal research support. In addition, many of the manipulative treatment protocols in these studies do not model typical clinical practice, making it difficult to extrapolate the results to the clinical setting. This is particularly problematic in studies that attempt to establish rigorous controls or use placebo treatments such as detuned diathermy, sham laser treatments, or sham manipulations.

Acute Low Back Pain

The studies by Glover et al29 and Hadler et al30 of the effect of manipulation in patients with acute low back pain have received high quality scores in most reviews and are widely quoted to have established some legitimacy for manipulation. Glover et al29 compared two groups of patients, one that received a single manipulative treatment followed by four sessions of detuned diathermy (placebo) and the other five treatments of the placebo only. Significant (P < 0.05) improvement was reported in patients immediately after the initial manipulative treatment. However, there was no difference between groups after 3 or 7 days. Hadler et al30 randomized patients to receive either a single manipulative treatment or mobilization procedure. In patients with pain of 2 to 4 weeks' duration, there was significant (P = 0.009) difference in favor of SMT at 3 days, but not at 6 days, after treatment. Despite the positive short-term beneficial outcome of manipulation in these two studies, the use of a single manipulative treatment in both has been criticized as not modeling usual clinical practice. Mathews et al31 attempted to remedy this shortcoming by comparing a group of patients with acute lower back pain treated with up to 10 manipulative treatments with a group receiving 6 treatments of infrared heat applied to the lumbar spine. A significant (P < 0.05) difference was reported in recovery at 2 weeks for patients with lower back pain who also had leg pain, but not for patients with lower back pain only. There was no difference in relapse rate after 1 year.

MacDonald and Bell32 compared the effect of five spinal manipulative treatments done in combination with a low back education program with the effects of five low back education sessions alone. The results were not statistically significant in favor of manipulation but favored manipulation. Shekelle et al3 pooled the results of seven trials, using pain and functional outcome as clinical measures, and concluded that spinal manipulation had significant (P < 0.05) overall benefit, averaging approximately a 34% improvement in recovery compared with several alternative treatment methods. They calculated a pooled odds ratio of 0.17 probability of faster recovery at 3 weeks compared with other therapies. In a similar meta-analysis, Brønfort23 concluded that there was moderate evidence of short-term efficacy when SMT was used to manage acute low back pain. van Tulder and Waddell27 concluded that there is moderate evidence that manipulation is more effective than placebo for short-term relief of acute low back pain; however, they also stated that it was not yet possible to judge whether manipulation is more effective than nonsteroidal anti-inflammatory drugs or physical therapy. This type of review led the Agency for Health Care Policy and Research in 1994 to add manipulation to its short list of recommended treatments for acute low back pain.5

Chronic Low Back Pain

The study by Koes et al33 of SMT in patients with chronic low back pain has received high quality scores. The authors compared a course of 14 SMT treatments with three other treatment approaches. One included massage, heat, and modalities such as electrotherapy, ultrasound, and diathermy; another consisted of medical management with anti-inflammatory medications and advice; the third invloved detuned modalities (placebo). At 1-year follow-up, they found significant (P = 0.05) benefit in terms of pain, but not physical functioning, for patients treated with spinal manipulation compared with the group that received massage, heat, and modalities. There was significant benefit for spinal manipulation over medical management (P = 0.05) and over placebo modalities (P = 0.02) at 6 weeks but not at 12 weeks.

Pope et al34 conducted a four-arm clinical trial in patients with chronic low back pain. They compared a group of patients treated with nine spinal manipulative treatments with three other treatment protocols (massage, transcutaneous electrical muscle stimulation, or corsets). At 3-week follow-up, SMT showed a significant (P < 0.05) benefit in terms of disability score. However, this improvement was not found to extend to pain scores, where the only significant (P = 0.05) benefit was found in the comparison with transcutaneous muscle stimulation.

Triano et al35 compared conventional spinal manipulation provided daily for 2 weeks with a similar number of placebo manipulations using measured forces below a previously identified manipulative threshold. A third group of patients received the same number of structured education sessions. The differences in Oswestry disability scores between those treated with manipulation and placebo reached statistical significance (P = 0.004) at 2 weeks but not at 4 weeks. No comparison was made with the back education program. At 4 weeks, the difference in pain scores between manipulation and placebo manipulation were not statistically significant. However, the authors placed constraints on the manipulative treatments to adequately mimic the placebo treatments.

The most comprehensive study of the long-term effects of manipulation was done by Meade et al.36 They compared nine spinal manipulative treatments done in private chiropractic offices with six hospital-based physical therapy clinic sessions that included conventional physical therapy as well as spinal manipulation in a cohort of 741 patients. They reported significant (P < 0.05) benefits for the group treated by the chiropractors in terms of pain at 6-week, 6-month, and 1-, 2-, and 3-year follow-ups and in terms of disability at 6-month and 2- and 3-year follow-ups. However, this study has been criticized for having excessive numbers of patients lost to follow-up as well as for differences in treatment settings.

Cherkin et al37 conducted a randomized clinical trial in a group of 321 patients with acute or chronic low back pain of at least 7 days' duration. Patients were assigned to SMT or physical therapy according to the McKenzie method or were provided an educational booklet about back pain. The group treated by chiropractors did significantly better than the group receiving the booklet at 4 weeks (P = 0.02) but not at 12 weeks, 1 year, or 2 years. However, there was no difference between patients who received SMT and those treated with physical therapy. Although disability scores appeared to be better for the groups treated with manipulation and physical therapy than for the group given the booklet, this was not statistically significant. In the groups that received active treatment, approximately 75% of patients reported that their care was good or excellent, while only 30% of those in the group given the booklet reported receiving good or excellent care (P < 0.001). One limitation of this study was the rather low level of initial symptoms that, combined with the usual trend to spontaneous improvement of low back pain, resulted in a statistical floor effect restricting the ability to detect differences between treatment groups.

Until recently, systematic reviews and meta-analyses of trials in patients with chronic low back pain have not been as positive as those of patients with acute pain. The issue has been complicated by inconsistency between studies, with some showing a beneficial effect on pain but not disability, and others reaching the opposite conclusion. However, in none of the studies has it been shown that manipulation is less effective than any treatment approach with which it has been compared. In their systematic review, van Tulder et al24 concluded that there was strong evidence that manipulation was more effective than placebo and moderate evidence that manipulation was more effective than several other treatments with which it had been compared. Brønfort23 concluded that there was moderate evidence of a short-term effect of manipulation in chronic low back pain but inconclusive evidence of a longterm effect. In the review by the Swedish Council on Technology Assessment in Health Care in 2000, using the Cochrane Collaboration methodology, van Tulder and colleagues concluded that “there is strong evidence that manual therapy is more effective than a placebo treatment for short-term relief”27 of acute low back pain, although they found insufficient evidence to determine whether it is better than other physical therapeutic interventions or drug therapy. In an examination of the literature on chronic low back pain, the authors found that “there is strong evidence that manual therapy provides more effective short-term pain relief than a placebo treatment” and moderate evidence that “manual therapy is more effective than usual care by the general practitioner, bed rest, analgesics and massage for short-term pain relief.”28 However, they also concluded that “there is limited and conflicting evidence of any long-term effects.”28

Two recent studies have compared the treatment of back pain patients by chiropractors with that by various other providers. Skargren et al38 randomized 323 patients with back and neck pain to chiropractic treatment or treatment by physical therapists. The authors found no significant overall difference in the cost or outcome of treatment. However, chiropractic treatment was favored in the group with a short duration and high level of symptoms, whereas physical therapy was favored in those with more chronic symptoms. Some questions have been raised about their conclusions because of restrictions that the experimental protocol placed on the chiropractic treatment. Nonetheless, the findings of Skargren et al38 suggest overall similarity in benefit between treatments incorporating SMT and those using intensive physical therapy.

Hurwitz et al39 randomized 681 patients with low back pain in a managed care setting to conventional medical treatment with or without physical therapy or to chiropractic care with or without physical modalities. They found that all groups improved over 6 months of follow-up without any significant differences in disability or pain between the patients treated by chiropractors and those treated by medical providers with or without physical therapy. Although these studies38,39 do not specifically address the question of benefit of SMT as an isolated intervention, their results argue that care incorporating spinal manipulation does at least as well as the best medical management.

Radiculopathy and Disk Herniation

While most studies on the effects of spinal manipulation on patients with radiculopathy and/or disk herniation have been individual case reports or uncontrolled small case series, there have been three randomized clinical trials40-42 and one nonrandomized clinical trial.43 Most of the small studies had no control or comparison group. The authors of the randomized clinical trials compared manipulation with other nonsurgical measures (eg, traction, exercise, heat treatments), and all reported an advantage for spinal manipulation at 2 to 6 weeks.40-42 In one of the studies, patients were followed for 1 year, and no difference in relapse rates was reported.42 The authors of the nonrandomized trial compared manipulation with surgical intervention and reported greater benefit with surgery.43 A trial of single-session lumbar rotary manipulation was reported to significantly (P = 0.0045) improve the abnormal H-reflex amplitude in patients with unilateral lumbar disk herniation and radiculopathy; the abnormal H-reflex latency showed insignificant improvement (P = 0.3877).44 No complications or serious side effects that would preclude the use of manipulation in patients with radiculopathy were reported in any of the case series or trials. Manipulation is of uncertain benefit in patients with radiculopathy and well-designed studies in this area are needed.45

Spinal Stenosis and Spondylolisthesis

No randomized clinical trials of patients with spinal stenosis, spondylolisthesis, or spondylolysis have been done. In their case series of patients with spinal stenosis, Kirkaldy-Willis and Cassidy46 reported favorable results in the group treated with SMT. They also reported the responses of 283 consecutive patients with low back pain to spinal manipulation, 25 of whom had spondylolisthesis.46 The response was similar to that noted in the other patients, and no adverse outcomes were reported.

Management of Common Disorders

Premanipulation Examination

The premanipulation evaluation of patients is similar to the routine orthopaedic assessment of patients with low back pain, but with certain characteristics unique to practitioners of manipulation. The three-step process of evaluation consists of establishing a diagnosis, determining whether the patient is a candidate for spinal manipulation, and deciding on the type of manipulation that should be used. Elements of the clinical history, including the mechanism and timing of onset of the symptoms, as well as aggravating and relieving activities and the effects of posture on symptoms, are useful for establishing the treatment plan and predicting the likelihood of effectiveness of a course of treatment.

Many practitioners of spinal manipulation, especially chiropractors, use radiographs to evaluate patients. Radiographs may help the practitioner determine the integrity of the underlying osseous structure to withstand the forces used in the treatment. They also may help in the analysis of spinal distortions and postural relationships that have been perceived as important in planning the type of manipulation. Although the former use of radiographs is clearly important, the latter is controversial. Radiographs, with certain exceptions, have not been shown to be predictive of spinal symptoms. Although there appears to be reasonable reliability in chiropractic interpretation of radiographic findings, it has yet to be established that the postural markings of relative vertebral position contribute to treatment effect and outcomes.

Radiographs often are necessary to aid in the appropriate premanipulation evaluation of patients with back pain. Before January 2000, Medicare required radiographic demonstration of a subluxation for all patients treated by chiropractors, forcing most offices to maintain their own facilities. With the change in Medicare regulations and the revision of medical ethics allowing referral to chiropractors, medical radiographic facilities have become more accessible to chiropractors. Also, radiologists have become more aware of the studies required by chiropractors, and there is a trend in the chiropractic community to refer patients to medical facilities for the necessary studies.

The primary diagnostic procedures used to determine the type of manipulation that may be most beneficial are postural analysis and manual palpation of the spine and paraspinal tissues. Of these two procedures, palpation is the most frequently applied for the identification of the manipulable lesion (eg, subluxation, fixation, osteopathic lesion). Static palpation, done with the patient in a relaxed (usually prone) position, is used to detect areas of muscle tension, tenderness, spasm, and segmental differences in tissue consistency. This is often followed by motion palpation, in which the clinician palpates individual spinal motion segments through various ranges of motion, evaluating each direction of motion for restriction and asymmetry of movement. Interexaminer reliability and reproducibility of these procedures is not high.47 Intraexaminer reliability is higher for some procedures, but this is of uncertain value.47

Spinal Manipulation Techniques

SMT for low back pain can be divided into three procedures: those preparatory to manipulation, manipulation itself, and those subsequent to manipulation. Preparatory treatments, such as cryotherapy, various types of stretching, and soft-tissue massage or reflex techniques, are usually done to relax the patient, reduce tension, and ease acute pain. When the pain is acute and severe or when significant muscle spasm is evident, such treatments often are followed by mobilization procedures rather than a specific manipulation.

If the preparatory therapies relax the patient sufficiently, spinal manipulation with impulse is applied to one or more of the abnormal spinal segments identified during examination. In the lumbar spine, the manipulative force may be directed in a posteroanterior direction on one of several spinal contacts, with the patient prone on a segmented table or plinth (Fig. 3). However, the most common lumbar manipulation is done with the patient in a side-lying position (Fig. 4), with the lower leg straight and the upper leg bent at the hip and knee. The upper body is braced by putting one hand on the patient's shoulder, traction is placed on the uppermost leg to produce rotational locking of the facet joints, and a thrusting impulse is administered at one of several spinal contact points. Depending on the findings in the postural and palpatory examination, the manipulative thrust can be applied to the spinous or transverse process, the sacrum, the ilium, or, in the case of long-lever techniques, the leg (Fig. 5). It is not uncommon for spinal manipulation to be applied to the thoracic and cervical spine even when the primary symptoms are in the lumbar region. The rationale for this approach is that there is interdependence between regions of the spine to allow proper movement and that each area contributes to correct posture and motion. Although attractive, this reasoning is largely hypothetical.

Figure 3
Figure 3:
Prone, short-lever technique with a primary vector of thrust from posterior to anterior. Contact is directly on one of several spinal contact points, and the thrust can be delivered with torque, depending on the type of movement desired.
Figure 4
Figure 4:
Side-lying, short-lever spinal manipulative technique.
Figure 5
Figure 5:
Side-lying, long-lever spinal manipulative technique.

Flexion-distraction treatment has been recommended for patients with disk herniation and has found favor with many manipulative practitioners. The patient is placed on a special table that introduces continuous mobilization of the lumbar spine while manual contact and force are applied to introduce an element of directed intersegmental lumbar traction. Although there is some evidence that this approach can increase the mobility of the lumbar spine and also cause some expansion of the intervertebral disk in the same manner as other traction procedures, its efficacy has yet to be demonstrated in randomized clinical trials.

Spinal manipulative treatment is usually followed by postural and ergonomic advice, recommendations for home exercise, and nutritional and lifestyle recommendations. Many practitioners also offer supports or orthotics in the hope of reducing postural factors that may cause recurrence of pain. Increasing numbers of chiropractors and practitioners in interdisciplinary treatment centers are incorporating spinal manipulation as part of a comprehensive rehabilitation process.

A major topic of contention and confusion is the number of manipulative treatments that are reasonable and necessary to achieve optimal results. The consensus is that some degree of improvement may be expected within 2 weeks of treatment at a frequency of three to five treatments per week.48 Lack of improvement after 4 weeks, or 12 treatments, is reason to discontinue treatment until further examination of the patient has been done.48 If the patient shows progressive improvement of symptoms at 4 weeks, treatments may be tapered to two per week, then to one. However, most patients with acute or episodic uncomplicated low back pain respond to just a few treatments and tend to return only when there is recurrence of pain. Standard treatment protocols suggest that patients should be reevaluated every 2 weeks to determine whether the treatment is successful.48 Such protocols are not very different from those for physical therapy, exercise, medication, and other nonsurgical treatments for low back pain.

The primary difference between the treatment protocols for chronic low back pain and those for acute pain is that, with chronic back pain, a lesser intensity of initial treatment and a longer duration of overall therapy is common. Ergonomics, lifestyle, and exercise recommendations also play a greater role in the treatment of patients with chronic back pain.

The treatment of asymptomatic or minimally symptomatic individuals on a prophylactic or maintenance basis has been controversial among practitioners of SMT in general and chiropractors in particular. Currently, there is no evidence that prophylactic treatment either prevents or modifies the occurrence of subsequent back problems or the appearance or course of other disorders.

Complications

Serious complications caused by spinal manipulation are rare and very poorly documented.2 There have been a few case reports of herniated intervertebral disks and even of cauda equina syndrome3 after manipulation. The precise incidence of these complications is unknown and is probably underreported, although even the degree of underreporting is not known. Shekelle et al3 estimated the serious complication rate for lumbar manipulation at 1 in 100 million manipulations, but that conclusion was based solely on reported cases. Senstad et al49 reported that minor, self-limited side effects of manipulation are quite common. The most typical reactions, usually lasting less than 24 hours but occasionally as long as 48, were local discomfort in the area of treatment, pain in areas other than that of treatment, fatigue, and headache. None of the clinical trials of lumbar manipulation reported any complications, which indicates that spinal manipulation is a relatively safe form of lumbar spine treatment and is considerably safer than many of the medications that can be used either alone or in combination with SMT to manage back pain.

Contraindications

Physical force should not be placed on a spine that cannot structurally withstand it. Therefore, destructive lesions of the spine, acute fracture, or osteomyelitis are absolute contraindications to lumbar manipulation. Osteoporosis and bleeding disorders are conditions that mandate caution, especially when considering impulse manipulation. Rheumatoid disease with acute inflammation or ligamentous instability is also a contraindication to forceful manipulation, but mobilization and massage may be considered in specific situations. Patients who take medications that could affect the appropriateness of SMT, such as long-term glucocorticoids or anticoagulants, also may be unsuitable.

The presence of disk herniation or severe spondylosis often requires modification of the treatment approach, but they are not absolute contraindications to spinal manipulation in the absence of neurologic deficit. Progressive neurologic deficits or cauda equina syndrome are absolute contraindications to spinal manipulation. However, patients with stable, long-standing, thoroughly evaluated neural defects may be considered as candidates.

Summary

Spinal manipulation is a common and generally safe method of lower back pain therapy. Research indicates that SMT for acute and chronic back pain provides at least short-term benefits. A growing number of patients with back pain are treated with manipulation, and most express a high degree of acceptance of and satisfaction with such procedures. Because of this patient satisfaction, as well as a growing awareness of the clinical trials supporting the effectiveness of manipulative procedures to treat specific categories of patients with back pain, SMT and its practitioners have been incorporated into conventional medical settings. This assimilation is expected to continue, and models of treatment participation and cooperation are being developed and refined. Manipulation therapies in general and chiropractic treatments in particular are now covered by Medicare and most health insurance and HMO plans. The primary motivation for inclusion has been demand by patients and insurance plan subscribers for such services.

The intense scrutiny of spinal manipulative procedures that has been the hallmark of the past decade can be expected to continue. With a more established research infrastructure, it should be easier to conduct studies in multidisciplinary settings. Many questions remain unanswered, such as whether particular subgroups of patients with back pain are more likely to benefit from manipulative treatments and whether certain manipulative techniques are markedly more efficacious or hazardous than others. Identification of the mechanism through which manipulation affects symptoms is under increasing investigation. Comparative studies with other forms of treatment, as well as studies to determine whether there are added benefits of combining treatment modalities, are ongoing. Further research should define the exact role of spinal manipulation in the treatment of patients with low back pain, the optimal duration and intensity of treatment, and the cost-effectiveness of SMT relative to other treatment options.

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