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Journal of Back and Musculoskeletal Rehabilitation Journal of Back and Musculoskeletal Rehabilitation 5 (1995) 121-133
Common treatments for low back pain: have they been proven effective? Philip J. Marion National Rehabilitation Hospital, Washington, DC 20010, USA
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Abstract The etiology of low back pain can be complex and the specific etiologies are rarely separated for investigation. There continues to be no single clinically proven superior treatment for low back pain. This may explain the multiplicity of treatments available. The purpose of this article is to evaluate the different forms of treatment for low back pain, treatment outcome and effectiveness. Nine more common treatments for low back pain are described. The long term effectiveness of the procedures reviewed in this article for the treatment of low back pain remains doubtful. For the majority of patients with complaints of low back surgery is not indicated. For those patients who have neurological deficits and a documented lesion, surgery can be an immediate and appropriate treatment. The conventional treatment for low bacl~ pain continues to be the triad of rest, analgesic medication and perhaps exercise after the acute phase of low back pain. None of the other treatment options evaluated in this review were consistently shown to be more effective than this traditional triad treatment course. Keywords: Back pain; Treatment; Outcome; Procedure
1. Introduction
Low back pain is a common patient presentation in a hospital or office setting. Approximately 80% of the population will suffer from low back pain at some point in their adult life [1]. The majority of cases are initially seen by primary care physicians [2]. The number of health care visits and resultant financial expenditures are enormous with estimates in excess of 20 billion dollars for the comprehensive treatment of low back pain [3]. For the majority of cases, low back pain
syndrome is self-limiting. Approximately 93% of patients with low back pain will improve within 6 months and 74.2% within the first month. Less than 8% of patients with low back pain continue to have pain for greater than 6 months [4]. Usually, patients with low back pain are given a nonspecific diagnosis. The etiology of acute low back pain can include infection, neoplasm, trauma, vascular disease and psychological overlay [5,6]. Low back disorders of unspecific origin can be separated into general syndromes including myofascial pain, low back strain, sciatica and
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facet syndromes [7]. Various treatments have been recommended, but the initial treatment is often conservative, consisting of bed rest and analgesic medications [5,8]. Although several treatment protocols have been developed with increasing levels of invasiveness for patients with persistent low back pain [9], few treatment regiments have proven to be superior to other treatment modalities [10]. The purpose of this paper is to evaluate the different forms of treatment for low back pain, assess treatment outcomes and discuss effectiveness. Nine common treatments are described in order of ascending cost [11] in Table 1. 2. Bed rest
The least costly and most commonly prescribed treatment for non-traumatic acute low back pain is bed rest. Bed rest may be effective since intradisc pressure is decreased when a patient is in a horizontal position and the trunk muscles are relaxed [12,13]. Wiesel evaluated the role of bed rest for the treatment of low back pain of military recruits in a prospective randomized study [14]. Eighty subjects who complained of localized low back pain and had a normal neurological examination were evaluated. The experimental group was hospitalized and treated with bed rest. In this military setting, compliance was easily enforced. The control group subjects were kept ambulatory and assigned a restricted duty status which elimi-
Table 1 Low back pain treatment I.
Non-surgical treatment A. Rest
B. Medication C. Physical therapy/exercise therapy D. Manipulation therapy II.
Procedures A. Trigger point injection
B. Facet joint injection C. Spinal epidural injection III.
Surgery A. Chemonudeolysis
B. Laminectomy/fusion (Source: Author.)
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nated all physical exercise. They were released to full duty when their pain disappeared and there were no abnormal physical or neurological findings. The results of this study noted a statistically significant difference in the experimental bed rest versus control group based upon the number of days required to return to full activity. The group receiving bed rest returned to full duty in 6.6 days compared to 11.8 for the ambulatory group. This study however, did not determine the optimal number of days of bed rest for acute low back pain. Furthermore, the evaluators were not blinded, which may have introduced investigator bias. A prospective randomized blinded study by Deyo et al. [15] addressed the optimal duration of bed rest for the treatment of acute low back pain. Two-hundred and three subjects were studied with outcome data obtained at 3 weeks and 3 months. The patients' self rating was elicited by individuals who were blinded to study group assignment. Subjects were randomly assigned 2 or 7 days of bed rest. There were no clinical or demographic differences noted between the two groups. Group one subjects prescribed 2 days of bed rest, reportedly missed 45% fewer days of work than group two subjects assigned 7 days bed rest. This was statistically significant (P = 0.01). The authors concluded that the prescription of two days bed rest was as effective as 7 days for the treatment of acute low back pain. Of particular note is that subjects seeking financial compensation from their employer were excluded. They also reportt,;d a substantial number of subjects who refused to participate in the study. It was their impression that the subjects who declined had similar clinical demographic characteristics as the participants. Other studies support bed rest as an effective treatment option for acute low back pain [3,16-18]. In addition to being the most commonly prescribed and least costly treatment, the prescription of bed rest is the least invasive. The direct cost of bed rest treatment is essentially reflected in the charge for a physician visit. The author suspects that most patients with complaints of acute low back pain do not initially present to a
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physician and more likely they themselves prescribe bed rest. The self-limiting nature of acute low back pain and the minimal direct cost of bed rest as a treatment results in a high ratio of cost-effectiveness. This however, does not address the indirect cost of lost work productivity which would vary depending upon the number of days of bed rest prescribed, of work lost and the value of the work performed. 3. Medications Medications are often prescribed for the treatment of low back pain. The four major general categories include non-steroidal anti-inflammatory drugs (NSAIDs), analgesics, anti-depressants and muscle relaxants.
3.1. Non-steroidal anti-inflammatory drugs (NSAIDS) / analgesics NSAIDS reduce the signs and symptoms of inflammation including pain and muscle tenderness. Many NSAIDS also have analgesic properties. Their most common adverse effect is gastrointestinal and anti-coagulation [19]. The effects of NSAIDS on low back pain are not clear. A prospective double-blind interpatient comparison study [20], comparing indomethacin and a placebo showed no statistical difference in the alleviation of pain between the two groups after 14 days of treatment. Outcome assessment post treatment was based upon the subjective patient reporting of pain radiation and straight leg raise testing. Hickey [21] evaluated diflunisal (Dolibid) and paracetamol in the treatment of chronic low back pain. Sixteen patients were treated with diflunisal and 14 patients with paracetamol. Patients were included if they had low back pain for at least 6 months and had been unresponsive to previous treatments. Incidently, all subjects had a prior diagnosis of facet joint syndrome and were initially referred for lumbar spine facet joint injection. After completing a 4-week medication treatment course, patients were evaluated based upon their subjective responses and objective clinical and physical signs. The results of the rating scales for patients treated with diflunisal reported a
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significant increase in function and decreased pain compared to paracetamol. The author concluded that diflunisal was equally as safe as paracetamol and had significantly greater efficacy. He also concluded that diflunisal is a highly effective, well tolerated and safe drug for use in patients with chronic low back pain. This study was limited however, by the lack of control group or placebo. Given the relatively small number of total subjects and lack of blinded assessment, more research is needed before Hickey's conclusion can be supported. Berry et al. [22] found different results with diflunisal. In a study comparing naprosyn, diflunisal and placebo, 30 patients with chronic low back pain were entered into a randomized double-blind crossover experiment. Patients with chronic low back pain of at least 3-months duration were selected. Each treatment was assessed at 14-day intervals. Pain assessment was performed utilizing a vertical visual analogue scale and a 4-point scale. Pain measurement assessment showed a statistically significant reduction in pain for patients utilizing naprosyn. There was no significant change for patients utilizing diflunisal or placebo. The authors concluded that naprosyn was superior in relieving pain compared to both diflunisal and placebo. Diflunisal was also compared to acetaminophen with codeine in the treatment of many forms of mild to moderate musculoskeletal pain which included acute low back pain [23]. Forty-two patients were randomly assigned to one of two groups and there was no significant difference in pain relief. There were fewer reported side affects for patients utilizing diflunisal but this was not statistically significant. Patients in this study had various forms of pain with a subcategory of low back pain. The evaluation of the diflunisal or acetaminophen with codeine specific to low back pain was not addressed.
3.2. Muscle relaxants Muscle spasms are often viewed as an etiology of low back pain. Muscle relaxants are often used for the treatment of muscle spasms. The usual dosage for the treatment of muscle spasms more likely has a sedative effect without actually caus-
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ing muscle relaxation [10]. In a double-blind trial of methocarbamol versus placebo in painful muscle spasms, Valtonen [24] noted a significant effect in the treatment group. Patients selected for the study had either low back or neck pain. Each patient was provided with a bottle of tablets which were either methocarbamol or identical placebo. There was no comment regarding patient medication compliance. Subjective follow-up assessment was made utilizing a 3-point scale. The author noted a significant effect of methocardamol when compared to placebo. Unfortunately, patients with low back pain were not separated from those with neck pain to evaluate methocarbamol to that of placebo. Gready [25] compared methocarbamol plus aspirin (roboxisaI) with chlorzoxazone plus acetaminophen (parafon forte) for the treatment of patients suffering from various musculoskeletal disorders which included patients with low back pain. This double-blind randomized study assessed subjects over an 8-day period. Treatment assessment was based upon pain relief, degree of muscle spasm, tenderness over the area of the spasm and interference with routine activities. Patients reported the results based on as-point scale measuring pain, muscle spasms, muscle tenderness and return to routine functional activities. Both study groups reported a reduction in symptom severity; both medications were effective in reducing the severity of symptoms with minimal side affects. This study further revealed that parafon forte was significantly superior to roboxisal in reducing the severity of pain, spasms and limitation of motion. The author concluded that parafon forte is the drug of choice for the treatment of skeletal muscle spasms due to its greater efficiency in reducing pain, spasm and limitation of motion and has fewer side affects when compared to roboxisal. However, the difference in (measured) side effects between the two was not significant. Again, patients suffering from low back pain in either group were not separated from others with general musculoskeletal disorders, when evaluating the effectiveness of the above medications. Baratta [26] compared the effectiveness of another skeletal muscle relaxant, carisoprodol
(soma) in the treatment of low back syndrome and for the relief of stiffness. A double-blind comparative protocol was used to evaluate carisoprodol, proproxyphene (darvon) and placebo. Carisoprodol was significantly more effective than proproxyphene or placebo in relieving stiffness; however, there was no significant difference between drugs in measured pain relief. The authors concluded that carisoprodol was superior in the treatment of patients with low back syndrome in relieving stiffness compared to proproxyphene or placebo. However, none were significantly effective for pain relief. Brown [27] compared a tricyclic skeletal muscle relaxant, cyclobenzaprine hydrochloride (flexeriI), diazepam (valium) and placebo. The study was a double-blind randomized comparison. Patients reportedly had moderate to severe pain in the lumbar or posterior cervical regions for at least 12 months. Based on a 2-week study utilizing a 5point assessment scale, patients receiving cyclobenzaprine or diazepam showed significant improvement as compared to the placebo group. The authors noted that cyclobenzaprine was as effective as diazepam in the treatment of patients with skeletal muscle spasms. There was no significant difference in the improvement of pain between the two treatment groups.
3.3. Anti-depressant medication
Many patients with low back syndrome may have underlying depression which may inhibit their routine activities of daily living and exacerbate their low back pain [28,29]. A tricylic antidepressant medication, imipramine (tofraniI) was compared to placebo in a double-blind randomized trial [30]. At each visit during the study, patients completed a back pain questionnaire to access medication compliance, functional status, degree of back pain and psychological responses to low back pain. Dry mouth was the most significant side effect of patients treated with imipramine. There was significant improvement for patients receiving imipramine over placebo in the treatment of low back pain. In another prospective double-blind study, patients with chronic low back pain and depression were treated with desipramine or doxepin
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[31]. Patients selected were diagnosed as having low back pain and a major affective disorder; either uni-polar depression or dysthymia. All subjects had stable chronic low back pain for 6 months or longer. There was no significant difference between doxepin or desipramine. Both medications showed a statistically significant improvement in pain severity and depression. Non-steroidal anti-inflammatory agents, analgesics, muscle relaxants and tricyclic anti-depressants may have a role in the treatment of low back pain. Most of the studies reviewed were hampered by small sample size, absent control group, non-blinded assessment, inadequate follow-up or inconsistent outcome measures. In addition, not all studies were specific for patients with low back pain. The direct cost may not be as great for pharmacological treatment of low back pain if generic equivalents are utilized. Further studies comparing the above medication categories with acetaminophen or aspirin, likely the most common and least costly medications used for low back pain, are warranted. Also not addressed were the indirect costs of adverse drug reactions which would also decrease overall clinical effectiveness. 4. Exercise
Exercise is often used as a treatment modality for patients with low back pain in the form of physical therapy, home-exercise programs or as a component of low back schools [7,10]. Exercises may be prescribed to increase spinal range of motion (especially flexion and extension) and to strengthen paravertebral muscles. Kendall and Jenkins [32] in a double-blind controlled trial, compared three groups receiving flexion, mobilization or extension exercises for the relief of low back pain. Each of the three groups reported an improvement in low back symptoms, based on the number of painful episodes and subjective pain intensity. The authors concluded that while each exercise group experienced an improvement in low back symptoms, flexion exercises were superior to general mobilization exercises or extension exercises. However, the authors made their conclusion without statistical evi-
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dence. The study lacked control groups for statistical comparison and there was no patient clinical differentiation of localized back pain versus pain with sciatica. Davies et al. [33] did not find isometric flexion exercises to have a major influence on the recovery of patients suffering from low back pain. Patients with low back pain symptoms between 3 weeks and 6 months duration were evaluated. Subjects were randomly assigned to three treatment groups; short wave diathermy, back extension exercises with short-wave diathermy, and lumbar isometric flexion exercises with short-wave diathermy. Treatment protocols were performed over a 4-week period and subjective reporting assessments were recorded for each treatment group. There was significant pain reduction and increased spinal flexibility for each treatment group. The authors concluded that isometricflexion exercise was not superior to diathermy or extension exercise for the outcome measure of work resumption. Unfortunately, the absence of a control group may reflect the improvement measurements as the natural history of the disease. Additional problems with exercise protocol studies for the treatment of exercise will be addressed later. Estlander et al. [34] performed a comprehensive 4-week physical exercise treatment program in a non-controlled study for patients with chronic low back pain. The authors noted an increase in spinal mobility and strength. Follow-up evaluations at 3 weeks and 12 months showed significant decrease in subjective disability and pain. The percentage of patients who returned to work however, was unchanged. Similar results were found in a much larger study. Approximately 12000 subjects participated in 6-week exercise program for the treatment of low back pain [35]. Approximately 81 % of the participants reported less pain based upon a 5-point pain rating scale. However, as with the above studies, there was no control group. Other studies have not proven the efficacy of exercise in the treatment of patients with low back pain. White [36] evaluated workers' compensation patients with low back pain. He found no significant benefit of exercise therapy for the relief of pain or improved function. The author
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stated that the role of patient secondary gain due to the monetary compensation system may have been a factor in the study results. Gilbert et al. [37], in a multi-centered randomized clinical trial did not show significant improvement for patients receiving manual physical therapy. The literature is mixed with regard to the utility of exercise as a treatment for low back pain. In the studies reviewed, there is no differentiation between the etiology or categorization of low back pain. Most studies have a small sample size and no control group. Therefore, the efficacy of exercise in the treatment of patients with low back pain remains questionable. Since the exercise program protocols are variable and patient compliance is often rarely assessed, it is difficult to develop exercise program standardization. Often, exercise therapy is provided by different therapists within the same exercise treatment program. The level of ability of the therapists and participants are variable. Base line physical conditioning status differs within subject groups which may affect full participation by each subject. Within many treatment protocols, home-exercise programs are prescribed where subject compliance is also a problem and difficult to monitor. The cost factor varies depending upon the duration and frequency of a particular program. Individual treatments tend to be much more expensive than group treatments; however, both usually surpass the cost of a routine physician office visit. 5. Spinal manipulation therapy One of the more controversial forms of treatment for low back pain is spinal manipulation [38-40]. The benefits of spinal manipulation may be secondary to increased joint flexibility in the areas of reduced mobility and the freeing of connective tissue adhesions. Spinal joints are passively moved or mobilized. Several authors have evaluated the many clinical trials measuring the effectiveness of manipUlation therapy for low back pain [10,40-43] and suggest that manipulation therapy may have temporary short term benefits. In a prospective randomized study [44] manipulation therapy was compared to physiotherapy, corset use or analgesic tablets in patients with low
back pain. Patients reported no significant benefit of manipulation therapy compared to the other treatments at 6-weeks, 3-months or I-year followup. Hoehler et al. [45] compared vertebral manipulation therapy with a control group receiving soft tissue massage. In a randomized clinical trial, the group receiving manipulation treatment reported an immediate significant relief after the first treatment. However at discharge, (approximately 3-4 weeks) there was no measured significant difference between groups. The authors concluded that they could not provide evidence demonstrating the long term effectiveness of manipulation therapy. Manipulation of the lumbar spine was compared to the treatment of microwave diathermy, isometric abdominal exercises and ergonomic instruction in a prospective clinical trial [46]. Patients with acute low back pain and a normal neurological examination were placed into two groups consisting of manipulation therapy and what the authors termed a standard physical therapy treatment program for the treatment and control groups, respectively. There was a significant decrease in pain duration of the manipulation treatment group. This study, however, did not evaluate the longer term effectiveness of manipulation treatment. Godfrey et al. [47] concurred with the finding of short term improvement for patients receiving manipulation therapy in a single-blind randomized clinical trial. Patients receiving manipulation therapy were compared with a control group receiving message and low level electric stimulation. There was no difference in improvement scores between these two groups. Similar to manual physical therapy and exercise programs, spinal manipulation treatment varies with practitioner technique and ability. A problem with the current research is that specific manipulation techniques utilized within a study are often poorly des.cribed. The etiology or specific diagnosis is rarely described. Except for the study by Glover [40] rarely has manipulation been scientifically shown to be a long term efficacious treatment option for patients with low back pain. Further scientific studies are needed to demon-
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strate any long term permanent efficacy of manipulation therapy. 6. Trigger point injections
Foci of muscular spasms or irritation are often termed trigger points. These areas may cause pain resulting in stiffness and decrease strength. Trigger points are defined as a focus of tissue hyper-irritability [48]. Tenderness of this area and possible referred pain can be elicited upon palpation. Trigger points are associated with myofascial pain syndrome as a form of low back pain [49]. Garvey et al. [50], evaluated the efficacy of trigger point therapy in a prospective randomized double-blind study. A total of 63 patients were evaluated with the diagnosis of low back pain. All had a normal neurological examination. The subjects were randomly assigned into one of four treatment groups; lidocaine injection, lidocaine and steroid injection, dry needle injection or vapor coolant spray with accupressure. Outcome assessment was based on a self-reporting pain scale at the initial visit and study conclusion, but the follow-up interval time was not provided. At the study conclusion, the group which did not receive injection therapy (vapor coolantjaccupressure) reported the highest rate of improvement in pain symptoms at 66%. Both the dry needle injected and vapor coolant spray with accupressure groups reported a greater improvement in pain symptoms than the lidocaine and lidocaine and steroid injected groups. They concluded that the critical feature in pain relief from a trigger point injection was not related to the injected substance but the mechanical stimulus provided with either dry needle stick or vapor coolant spray with accupressure. In a randomized, double-blind crossover study, the effectiveness of different chemical compounds bupivacaine, etidocaine or physiological saline were evaluated as an agent in trigger point injection therapy [51]. After the injections, the subjective responses of 15 patients with myofascial pain syndrome were evaluated. The subjects reported better ratings for pain relief and muscle tension for the two anesthetic compounds versus normal saline. However, the number of patients
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were limited. The attrition rate was also not reported. This study did not address the role of trigger point injection in the specific treatment of low back pain since patients had the non-specific diagnosis of myofascial pain syndrome with or without back pain. Based on current evidence, there were no scientific studies which adequately address trigger point as an effective treatment for acute or chronic low back pain [52]. There is no standardized technique or consistent injectable compound utilized at this time for low back pain treatment. Most studies do not specifically address trigger point injections as a treatment modality specifically for low back pain. There is minimal scientific support for trigger point injection as the primary mode of low back pain treatment. As a conservative option for low back pain, treatment costs are modest yet effectiveness remains questionable. Additional studies are warranted including trigger point injection as an adjunct to exercise and medications. 7. Facet joint injection
Facet Joint Syndrome is a frequent yet nonspecific diagnosis for low back pain [53-55]. This syndrome is a poorly defined entity in which pain is thought to originate from the facet joints. The level of injection is based on the localization of the low back pain. The relief of pain by facet joint injection is considered diagnostic and therapeutic. Carrera [56] evaluated 20 patients with the diagnosis of facet joint syndrome complaining of low back pain. All patients underwent fluoroscopically guided intra-articular injection of a local anesthetic and steroid suspension. Thirteen of the 20 patients reportedly obtained immediate and complete pain relief while seven of the 13 patients reported a recurrence of back pain in less than 6 months. This study was limited in several respects. There were no control ,groups utilized. The evaluator was not blinded regarding the study outcome and there were no statistical comparisons. Carrera suggested that computer tomography has an important role in diagnosis of symptomatic facet arthropathy. Unfortunately, he also noted that this study did not
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address the efficacy of facet joint injection in the diagnosis and treatment of low back pain. Marks [57] in a prospective randomizeq comparison, evaluated the efficacy of facet joint injection and facet joint nerve block in· the diagnosis and treatment of patients with refractory chronic low back pain. There was no statistical difference for the immediate effects of facet joint injection or facet joint nerve block. Neither were there any long term differences in pain relief for either group. Marks concluded that facet joint injection or facet joint nerve block may be useful as a diagnostic tool for the diagnosis of facet joint syndrome but is of minimal benefit for the treatment in chronic low back pain. This study also suffered from the lack of a control group, no blinded outcome assessment or statistical comparisons. Jackson [58] evaluated 390 patients who suffered from localized lumbar back pain. The patients underwent intra-articular injections of local anesthetic and cortisone. Only 29% of the patients injected experienced initial pain relief. The authors determined that the facet joints were commonly not the single or primary source for low back pain in over 90% of the patients studied. This study again, could not show the efficacy of facet joint injection as a therapeutic intervention. The authors also acknowledged the lack of control group or double-blinded assessment. Lilius et al. [55] performed a prospective randomized clinical trial involving 109 patients with unilateral low back pain. The subjects were randomly assigned into three groups; cortisone and local anesthetic into two facet joints, the same mixture around two facet joints or saline into the facet joints. The subjects were evaluated at 1 h, 2 weeks and 6 weeks after treatment. They were also evaluated 3 months post-treatment. Sixty-four percent of the subjects reported initial pain relief and 36% reported continued benefit at the 3month follow-up evaluation, independent of the treatment received. Treatment outcome assessment included work attendance, pain relief and lumbar spine flexibility. The authors concluded that facet joint injection is a non-specific method of treatment and the results were secondary to the tendency for spontaneous recovery and psy-
chosocial components of back pain. The authors could not provide statistical or anecdotal evidence for facet joint injection as a useful treatment in low back pain or as a diagnostic tool. The diagnostic value and therapeutic effectiveness of facet joint injections remains controversial as a treatment option for low back pain. Diagnostic criteria has not been consistently established. This syndrome remains unclear as is the appropriate treatment. Compared to spinal epidural injections described later, a facet joint injection is the more costly of the non-surgical options for the treatment of low back pain. Proof of short term effectiveness is limited. Current evidence again has not shown facet joint injections as an effective long term treatment option for patients with low back pain. 8. Spinal epidural injections
Injection of steroid into the epidural space is the most frequently used non-surgically invasive treatment modality for low back pain. Injected epidural steroids may decrease the inflammatory component that contributes to the sciatic complaints of low back pain [59]. Benzon [60] reviewed the role of epidural steroid injections for low back pain and sciatica. He concluded that mechanical causes of low back pain, especially those accompanied by nerve root irritation, may respond to epidural steroid injections. Dilke [61] performed the first blinded prospective study of epidural injection in 1973. He reported significant effectiveness of epidural cortical steroid injection for the relief of low back pain. In a double-blind controlled trial, 100 consecutive patients were randomly assigned to a treatment (methylprednisolone and saline) or control (saline) group. Assessment outcome was based on relief of pain and resumption of normal occupation at 3-month follow-up. Approximately four times as many of the experimental subjects noted pain relief and returned to work, which was significantly better than the control group. Several authors question the effectiveness of epidural steroid injections for the treatment of low back pain. Rosen [62] retrospectively evaluated 40 patients who received epidural steroid
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injections for the treatment of low back pain and sciatica. Sixty percent of the patients reported improvement immediately after injection. Long term relief averaging 8 months was reportedly less than 25%. Fifty-three percent of the patients remained unable to return to normal activities at follow-up (average 8-month) evaluation. The authors concluded that epidural steroid injections should not be used in the long term management . of spinal stenosis or nerve root compression. They acknowledged that since this study was not double-blind and lacked a control group, there should have been a .bias toward a positive therapeutic response. Yet, the overall results showed the opposite effect. Cuckler [63] evaluated 73 patients with radicular pain in a prospective randomized double-blind study. Patients were injected with methylprednisolone acetate and procaine or saline and procaine as the control. At a 21 month average follow-up post-injection, there were no significant differences in pain relief between the experimental and control groups. They concluded that the use of epidural methylprednisolone acetate did not demonstrate any therapeutic efficacy in the treatment of acute or chronic neurocompression syndromes in the lumbar spine and was of uncertain value. White [64] evaluated 304 patients with low back pain who were injected with an epidural anesthetic and steroid under fluoroscopic guidance. The complaints of pain initially decreased dramatically but at 2 years follow-up more than 98% of the subjects reported a recurrence of low back pain. The authors concluded that epidural injections of steroids and anesthetic did not cure any of their patients and served only as a temporary relief for low back pain. During this study, the authors also noted a 25% needle placement error rate during epidural injections, which may impact treatment effectiveness. Snoek et al. [65], in a prospective double-blind study evaluated 51 patients suffering from low back pain related to herniated lumbar disc. The patients received either methylprednisolone or normal saline solution. There was no difference between the placebo and the steroid groups. Bush [66] in a prospective blinded control trial did not note a statistical significant difference at I-year
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follow-up for pain relief and mobility, except for the objective assessment of straight leg raise test for each of the two groups. Other authors [67,68] also reported that epidural injection of steroid and anesthetic may temporarily relieve low back pain and sciatica but rarely offers permanent relief. As a long term treatment of low back pain, most authors agree that the epidural injection of steroids is ineffective. Most studies do not differentiate localized low back pain versus chronic low back pain. Epidural steroid injections remains an invasive and costly technique with unsubstantiated value. 9. ChemoDucleolysis Chemonucleolysis is often characterized as a surgical procedure secondary to its significant complications and morbidity. A proteolytic enzyme, chymopapain is injected between the medial borders of the pericles and into the disc center, in order to dissolve herniated disc material [69]. Complications of chemonucleolysis have included anaphylaxis, infection, arachnoiditis and pulmonary embolism. Contra-indications include tumors, infections and metabolic etiologies of neuropathy. As outlined by McCulloch [70], appropriate selection of patients with sciatica due to herniated intervertebral disc is the single most important factor for success. A combination of patient symptoms, physical examination signs and radiological evidence must be obtained for proper patient selection. He recommended that chemonucleolysis be used only in those patients who would otherwise undergo a laminectomy or diskectomy. Evaluating the safety and efficacy of chymopapaine, Javid et al. [71] performed a double-blind randomized trial in patients diagnosed with herniated lumbar disease. The patients evaluated had prior extensive conservative therapies and were presented as candidates for laminectomy. Patients were assigned either to a placebo or chymopapain injection group. The treatment group reported significant improvement in pain at 6-months follow-up evaluation. The investigators determined that chymopapain was more effective than placebo for the treatment of patients: with herniated lumbar disc. They also suggested that
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chymopapain is an appropriate alternative for patients who are candidates for lumbar laminectomy. In a similar study Fraser [72] compared chymopapain with saline injections, in a randomized double-blind study of patients with documented lumbar disc disease. The preliminary results of this study at 6-months follow-up demonstrated a significant effect of chymopapain in the treatment of patients with disc herniation. A follow-up report [73] by Fraser evaluated the experimental and control groups 2 years post-injection. Sustained significant improvement of the chymopapain was noted in the treatment group. Fraser stressed the importance of appropriate clinical and diagnostic criteria for selecting appropriate patients for chemonucleolysis. He concluded the study by recommending chymopapain as the treatment of choice prior to consideration of disc fragment excision laminectomy. Crawshaw [74] evaluated the role of chemoneucloysis compared to surgery in the treatment of sciatica. Patients who failed to respond to conservative measures for the treatment of sciatica were placed in a chymopapain injection or surgery group. Subjects were assessed at 1 month, 3 months and 1 year. The failure rate in the chymopapain group was approximately 50%, compared to 11 % for the surgical group. The authors concluded that chemonucleolysis may be an appropriate step after the failure of conservative treatment prior to surgery but that chymopapain treatment failure should be immediately identified in order to pursue surgical options which may improve the surgical success rate. A 10-year follow-up evaluation compared chemonucleolysis to open discsectomy [75]. Both groups had a similar rate of re-operation and there was no difference of pain outcome measures. Chemonucleolysis procedures are now performed less frequently secondary to the inconsistent resultants, complications and morbidity. As treatment options become more aggressive and invasive, appropriate diagnostic criteria and patient selection are especially pertinent. Positive outcomes have been shown for appropriate patients undergoing chemoneucleolysis. Approximatelya reported 15% of patients do not respond
to chemonucleolysis and require further surgical intervention [71]. However, due to neurological complications, an allergic reaction rate of 0.5% and a 20% rate of persistent muscle spasms [5] it has more recently become less of a treatment option. 10. Surgery
The surgical treatment of low back pain and sciatica is usually indicated when a patient presents with a marked neurological deficit such as motor weakness, foot drop, bowel and bladder symptoms or unrelenting leg pain. A small percentage of patients who have a herniated disc, not resolved with conservative measures, may require surgery [76]. Proper selection of patients is critical for a successful outcome. Poor outcomes are related to lack of valid selection criteria, inaccurate diagnosis or psychological overlay [5]. Thomas et al. [77] compared the results of 86 patients with low back pain receiving surgical laminectomy to 32 patients receiving conservative treatment. Their criteria for surgical treatment were; one attack of low back pain and/or sciatica associated with loss of time from work and a filling defect on a myelogram. Patients undergoing surgical treatment had a laminectomy with removal of protruded disc material. Outcome was based on a non-blinded subjective 4-point scale. The authors concluded from the results of their questionnaire that laminectomy was an effective treatment for many patients who failed conservative efforts. They stressed that surgery must be provided earlier to improve outcome. Patients undergoing surgery who had symptoms for < 1 year improved at a rate of 81 % compared to patient having symptoms > 10 years with a 41 % improvement rate. Frymoyer et al. [78] evaluated the results of patients who underwent lumbar disc surgery in a lO-year follow-up study. The long term results of patients undergoing disc excision alone was compared to those undergoing disc excision with primary posterior midline surgical vertebral fusion. All patients evaluated were at least 10 years post-surgical procedure, averaging approximately 14 years. There were no statistical pre-operative
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symptom differences for each group. The study noted unsatisfactory results in approximately one third of the patients who had either surgical procedure at 10-year follow-up. A study by Weber [79] compared surgery with non-surgery treatments at 1-, 4- and 10-year follow-up. He noted significant improvement in the surgically treated group at the I-year follow-up examination. At 4 years and 10 years, there was no significant improvement noted for the surgical group. The outcome for patients receiving surgery for the treatment of low back pain are at best mixed. As emphasized by Frymoyer [5], appropriate patient selection is crucial for optimal outcome. Patients with marked neurological deficits are most appropriate for surgical intervention. Given the cost and risk of significant post-operative morbidity, a trial of conservative therapy should be tried initially. 11. Summary Since the etiology of low back pain can be complex, the specific etiologies are rarely separated for investigation. Including the studies reviewed, rarely are the etiologies discussed, categorized by location, type of symptoms, diagnosis or symptom duration. There continues to be no single clinically proven superior treatment for low back pain. This may explain the multiplicity of treatments available. The scope of this article and the limited number of rigorous scientific studies did not permit the inclusion of physical modalities such as heat, cold, ultrasound or electrical stimulation. It has been suggested that transcutaneous electrical nerve stimulation (TENS; another modality), is no more effective than placebo [80,81]. Only nine of the more common treatments were addressed in th\s review article. The conventional treatment for low back pain continues to be the triad of rest, analgesic medication and perhaps exercise after the acute phase of low back pain. The treatment triad of bed rest, analgesics with or without exercise remains the least costly option. None of the remaining treatment options evaluated in this review were consistently shown to be more effective than this traditional
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triad treatment course. Many of the procedures outlined may have a role, yet unproven for the immediate treatment of low back pain. The longer term effectiveness of epidural steroid injection or facet block for low back pain remains doubtful. In the majority of patients with complaints of low back pain, surgery is not indicated. Surgery for the treatment of low back pain is reserved for those patients who have progressive neurological deficits or severe intractable pain. For those patients who have neurological deficits and a documented lesion surgery can be an immediate and appropriate treatment. The specific type of surgery chosen; laminectomy, fusion or chemonucleolysis and their appropriate indications are still debated. Given the frequency of low back pain and its resultant economic toll, further studies including valid functional outcomes measures are desperately needed. References [1] Nachemson AL: The lumbar spine: an orthopedic challenge. Spine 1976;1(1):59-71. [2] Barton J, Haight RO, Marslan DWet al.: Low back pain in the primary care setting. J Fam Pract 1976;3:363-366. [3] Snook SH: The cost of back pain in industry. Spine State Art Rev 1987;2:1-5. [4] Abenhaim L, Subsa S: Importance and economic burden of occupational low back pain: a study of 2500 cases. J Occup Med 1987;29:670-671. [5] Frymoyer JW: Back pain and sciatica. N Engl J Med 1988;318(5):291-300. [6] Vukmir RB: Low back pain. Am J Emerg Med 1991;9:328-335. [7] Fast A: Low back disorders: conservative management. Arch Phys Med Rehabil 1988;69:880-891. [8] Borenstein D: Epidemiology, etiology, diagnostic evaluation, and treatment of low back pain. Curr Opin RheumatoI1992;2:226-232. [9] Cavin MB, Wiesel SW: Low back pain. Curr Opin RheumatoI1991;3:65-70. [10] Deyo R: Conservative therapy for low back pain: distinguising useful from useless therapy. JAmMed Assoc 1983;250(8): 1057-1062. [11] Allis W: The 1993 Physicians' Fee Reference, 10th edn. Wasserman, New York, 1993. [12] Nachemson AL: The influence of spinal movements on the lumbar intradisc pressure and on the tensile stresses in the annulus fibrosis. Acta Orthop Scand 1963;183-207. [13] Nachemson AL, Morris JM: In vivo measurements of intradiscal pressure: discometry, a method for the de-
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[14] [15] [16] [17] [18] [19] [20] [21] [22] [23]
[24] [25] [26]
[27] [28] [29] [30] [31] [32] [33]
P.J. Marion /1. Back Musculoskelet. Rehabil. 5 (1995) 121-133 termination of pressure in the lower lumbar discs. J Bone Joint Surg 1964;46A:1077-1092. Wiesel SW, Cuckler JM, DeLuca F et al.: Acute low back pain: an objective analysis of conservative therapy. Spine 1980;5:324-330. Deyo RA, Diehl AI
Journal of Back and Musculoskeletal Rehabilitation Journal of Back and Musculoskeletal Rehabilitation 5 (1995) 121-133
Common treatments for low back pain: have they been proven effective? Philip J. Marion National Rehabilitation Hospital, Washington, DC 20010, USA
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Abstract The etiology of low back pain can be complex and the specific etiologies are rarely separated for investigation. There continues to be no single clinically proven superior treatment for low back pain. This may explain the multiplicity of treatments available. The purpose of this article is to evaluate the different forms of treatment for low back pain, treatment outcome and effectiveness. Nine more common treatments for low back pain are described. The long term effectiveness of the procedures reviewed in this article for the treatment of low back pain remains doubtful. For the majority of patients with complaints of low back surgery is not indicated. For those patients who have neurological deficits and a documented lesion, surgery can be an immediate and appropriate treatment. The conventional treatment for low bacl~ pain continues to be the triad of rest, analgesic medication and perhaps exercise after the acute phase of low back pain. None of the other treatment options evaluated in this review were consistently shown to be more effective than this traditional triad treatment course. Keywords: Back pain; Treatment; Outcome; Procedure
1. Introduction
Low back pain is a common patient presentation in a hospital or office setting. Approximately 80% of the population will suffer from low back pain at some point in their adult life [1]. The majority of cases are initially seen by primary care physicians [2]. The number of health care visits and resultant financial expenditures are enormous with estimates in excess of 20 billion dollars for the comprehensive treatment of low back pain [3]. For the majority of cases, low back pain
syndrome is self-limiting. Approximately 93% of patients with low back pain will improve within 6 months and 74.2% within the first month. Less than 8% of patients with low back pain continue to have pain for greater than 6 months [4]. Usually, patients with low back pain are given a nonspecific diagnosis. The etiology of acute low back pain can include infection, neoplasm, trauma, vascular disease and psychological overlay [5,6]. Low back disorders of unspecific origin can be separated into general syndromes including myofascial pain, low back strain, sciatica and
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facet syndromes [7]. Various treatments have been recommended, but the initial treatment is often conservative, consisting of bed rest and analgesic medications [5,8]. Although several treatment protocols have been developed with increasing levels of invasiveness for patients with persistent low back pain [9], few treatment regiments have proven to be superior to other treatment modalities [10]. The purpose of this paper is to evaluate the different forms of treatment for low back pain, assess treatment outcomes and discuss effectiveness. Nine common treatments are described in order of ascending cost [11] in Table 1. 2. Bed rest
The least costly and most commonly prescribed treatment for non-traumatic acute low back pain is bed rest. Bed rest may be effective since intradisc pressure is decreased when a patient is in a horizontal position and the trunk muscles are relaxed [12,13]. Wiesel evaluated the role of bed rest for the treatment of low back pain of military recruits in a prospective randomized study [14]. Eighty subjects who complained of localized low back pain and had a normal neurological examination were evaluated. The experimental group was hospitalized and treated with bed rest. In this military setting, compliance was easily enforced. The control group subjects were kept ambulatory and assigned a restricted duty status which elimi-
Table 1 Low back pain treatment I.
Non-surgical treatment A. Rest
B. Medication C. Physical therapy/exercise therapy D. Manipulation therapy II.
Procedures A. Trigger point injection
B. Facet joint injection C. Spinal epidural injection III.
Surgery A. Chemonudeolysis
B. Laminectomy/fusion (Source: Author.)
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nated all physical exercise. They were released to full duty when their pain disappeared and there were no abnormal physical or neurological findings. The results of this study noted a statistically significant difference in the experimental bed rest versus control group based upon the number of days required to return to full activity. The group receiving bed rest returned to full duty in 6.6 days compared to 11.8 for the ambulatory group. This study however, did not determine the optimal number of days of bed rest for acute low back pain. Furthermore, the evaluators were not blinded, which may have introduced investigator bias. A prospective randomized blinded study by Deyo et al. [15] addressed the optimal duration of bed rest for the treatment of acute low back pain. Two-hundred and three subjects were studied with outcome data obtained at 3 weeks and 3 months. The patients' self rating was elicited by individuals who were blinded to study group assignment. Subjects were randomly assigned 2 or 7 days of bed rest. There were no clinical or demographic differences noted between the two groups. Group one subjects prescribed 2 days of bed rest, reportedly missed 45% fewer days of work than group two subjects assigned 7 days bed rest. This was statistically significant (P = 0.01). The authors concluded that the prescription of two days bed rest was as effective as 7 days for the treatment of acute low back pain. Of particular note is that subjects seeking financial compensation from their employer were excluded. They also reportt,;d a substantial number of subjects who refused to participate in the study. It was their impression that the subjects who declined had similar clinical demographic characteristics as the participants. Other studies support bed rest as an effective treatment option for acute low back pain [3,16-18]. In addition to being the most commonly prescribed and least costly treatment, the prescription of bed rest is the least invasive. The direct cost of bed rest treatment is essentially reflected in the charge for a physician visit. The author suspects that most patients with complaints of acute low back pain do not initially present to a
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physician and more likely they themselves prescribe bed rest. The self-limiting nature of acute low back pain and the minimal direct cost of bed rest as a treatment results in a high ratio of cost-effectiveness. This however, does not address the indirect cost of lost work productivity which would vary depending upon the number of days of bed rest prescribed, of work lost and the value of the work performed. 3. Medications Medications are often prescribed for the treatment of low back pain. The four major general categories include non-steroidal anti-inflammatory drugs (NSAIDs), analgesics, anti-depressants and muscle relaxants.
3.1. Non-steroidal anti-inflammatory drugs (NSAIDS) / analgesics NSAIDS reduce the signs and symptoms of inflammation including pain and muscle tenderness. Many NSAIDS also have analgesic properties. Their most common adverse effect is gastrointestinal and anti-coagulation [19]. The effects of NSAIDS on low back pain are not clear. A prospective double-blind interpatient comparison study [20], comparing indomethacin and a placebo showed no statistical difference in the alleviation of pain between the two groups after 14 days of treatment. Outcome assessment post treatment was based upon the subjective patient reporting of pain radiation and straight leg raise testing. Hickey [21] evaluated diflunisal (Dolibid) and paracetamol in the treatment of chronic low back pain. Sixteen patients were treated with diflunisal and 14 patients with paracetamol. Patients were included if they had low back pain for at least 6 months and had been unresponsive to previous treatments. Incidently, all subjects had a prior diagnosis of facet joint syndrome and were initially referred for lumbar spine facet joint injection. After completing a 4-week medication treatment course, patients were evaluated based upon their subjective responses and objective clinical and physical signs. The results of the rating scales for patients treated with diflunisal reported a
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significant increase in function and decreased pain compared to paracetamol. The author concluded that diflunisal was equally as safe as paracetamol and had significantly greater efficacy. He also concluded that diflunisal is a highly effective, well tolerated and safe drug for use in patients with chronic low back pain. This study was limited however, by the lack of control group or placebo. Given the relatively small number of total subjects and lack of blinded assessment, more research is needed before Hickey's conclusion can be supported. Berry et al. [22] found different results with diflunisal. In a study comparing naprosyn, diflunisal and placebo, 30 patients with chronic low back pain were entered into a randomized double-blind crossover experiment. Patients with chronic low back pain of at least 3-months duration were selected. Each treatment was assessed at 14-day intervals. Pain assessment was performed utilizing a vertical visual analogue scale and a 4-point scale. Pain measurement assessment showed a statistically significant reduction in pain for patients utilizing naprosyn. There was no significant change for patients utilizing diflunisal or placebo. The authors concluded that naprosyn was superior in relieving pain compared to both diflunisal and placebo. Diflunisal was also compared to acetaminophen with codeine in the treatment of many forms of mild to moderate musculoskeletal pain which included acute low back pain [23]. Forty-two patients were randomly assigned to one of two groups and there was no significant difference in pain relief. There were fewer reported side affects for patients utilizing diflunisal but this was not statistically significant. Patients in this study had various forms of pain with a subcategory of low back pain. The evaluation of the diflunisal or acetaminophen with codeine specific to low back pain was not addressed.
3.2. Muscle relaxants Muscle spasms are often viewed as an etiology of low back pain. Muscle relaxants are often used for the treatment of muscle spasms. The usual dosage for the treatment of muscle spasms more likely has a sedative effect without actually caus-
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ing muscle relaxation [10]. In a double-blind trial of methocarbamol versus placebo in painful muscle spasms, Valtonen [24] noted a significant effect in the treatment group. Patients selected for the study had either low back or neck pain. Each patient was provided with a bottle of tablets which were either methocarbamol or identical placebo. There was no comment regarding patient medication compliance. Subjective follow-up assessment was made utilizing a 3-point scale. The author noted a significant effect of methocardamol when compared to placebo. Unfortunately, patients with low back pain were not separated from those with neck pain to evaluate methocarbamol to that of placebo. Gready [25] compared methocarbamol plus aspirin (roboxisaI) with chlorzoxazone plus acetaminophen (parafon forte) for the treatment of patients suffering from various musculoskeletal disorders which included patients with low back pain. This double-blind randomized study assessed subjects over an 8-day period. Treatment assessment was based upon pain relief, degree of muscle spasm, tenderness over the area of the spasm and interference with routine activities. Patients reported the results based on as-point scale measuring pain, muscle spasms, muscle tenderness and return to routine functional activities. Both study groups reported a reduction in symptom severity; both medications were effective in reducing the severity of symptoms with minimal side affects. This study further revealed that parafon forte was significantly superior to roboxisal in reducing the severity of pain, spasms and limitation of motion. The author concluded that parafon forte is the drug of choice for the treatment of skeletal muscle spasms due to its greater efficiency in reducing pain, spasm and limitation of motion and has fewer side affects when compared to roboxisal. However, the difference in (measured) side effects between the two was not significant. Again, patients suffering from low back pain in either group were not separated from others with general musculoskeletal disorders, when evaluating the effectiveness of the above medications. Baratta [26] compared the effectiveness of another skeletal muscle relaxant, carisoprodol
(soma) in the treatment of low back syndrome and for the relief of stiffness. A double-blind comparative protocol was used to evaluate carisoprodol, proproxyphene (darvon) and placebo. Carisoprodol was significantly more effective than proproxyphene or placebo in relieving stiffness; however, there was no significant difference between drugs in measured pain relief. The authors concluded that carisoprodol was superior in the treatment of patients with low back syndrome in relieving stiffness compared to proproxyphene or placebo. However, none were significantly effective for pain relief. Brown [27] compared a tricyclic skeletal muscle relaxant, cyclobenzaprine hydrochloride (flexeriI), diazepam (valium) and placebo. The study was a double-blind randomized comparison. Patients reportedly had moderate to severe pain in the lumbar or posterior cervical regions for at least 12 months. Based on a 2-week study utilizing a 5point assessment scale, patients receiving cyclobenzaprine or diazepam showed significant improvement as compared to the placebo group. The authors noted that cyclobenzaprine was as effective as diazepam in the treatment of patients with skeletal muscle spasms. There was no significant difference in the improvement of pain between the two treatment groups.
3.3. Anti-depressant medication
Many patients with low back syndrome may have underlying depression which may inhibit their routine activities of daily living and exacerbate their low back pain [28,29]. A tricylic antidepressant medication, imipramine (tofraniI) was compared to placebo in a double-blind randomized trial [30]. At each visit during the study, patients completed a back pain questionnaire to access medication compliance, functional status, degree of back pain and psychological responses to low back pain. Dry mouth was the most significant side effect of patients treated with imipramine. There was significant improvement for patients receiving imipramine over placebo in the treatment of low back pain. In another prospective double-blind study, patients with chronic low back pain and depression were treated with desipramine or doxepin
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[31]. Patients selected were diagnosed as having low back pain and a major affective disorder; either uni-polar depression or dysthymia. All subjects had stable chronic low back pain for 6 months or longer. There was no significant difference between doxepin or desipramine. Both medications showed a statistically significant improvement in pain severity and depression. Non-steroidal anti-inflammatory agents, analgesics, muscle relaxants and tricyclic anti-depressants may have a role in the treatment of low back pain. Most of the studies reviewed were hampered by small sample size, absent control group, non-blinded assessment, inadequate follow-up or inconsistent outcome measures. In addition, not all studies were specific for patients with low back pain. The direct cost may not be as great for pharmacological treatment of low back pain if generic equivalents are utilized. Further studies comparing the above medication categories with acetaminophen or aspirin, likely the most common and least costly medications used for low back pain, are warranted. Also not addressed were the indirect costs of adverse drug reactions which would also decrease overall clinical effectiveness. 4. Exercise
Exercise is often used as a treatment modality for patients with low back pain in the form of physical therapy, home-exercise programs or as a component of low back schools [7,10]. Exercises may be prescribed to increase spinal range of motion (especially flexion and extension) and to strengthen paravertebral muscles. Kendall and Jenkins [32] in a double-blind controlled trial, compared three groups receiving flexion, mobilization or extension exercises for the relief of low back pain. Each of the three groups reported an improvement in low back symptoms, based on the number of painful episodes and subjective pain intensity. The authors concluded that while each exercise group experienced an improvement in low back symptoms, flexion exercises were superior to general mobilization exercises or extension exercises. However, the authors made their conclusion without statistical evi-
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dence. The study lacked control groups for statistical comparison and there was no patient clinical differentiation of localized back pain versus pain with sciatica. Davies et al. [33] did not find isometric flexion exercises to have a major influence on the recovery of patients suffering from low back pain. Patients with low back pain symptoms between 3 weeks and 6 months duration were evaluated. Subjects were randomly assigned to three treatment groups; short wave diathermy, back extension exercises with short-wave diathermy, and lumbar isometric flexion exercises with short-wave diathermy. Treatment protocols were performed over a 4-week period and subjective reporting assessments were recorded for each treatment group. There was significant pain reduction and increased spinal flexibility for each treatment group. The authors concluded that isometricflexion exercise was not superior to diathermy or extension exercise for the outcome measure of work resumption. Unfortunately, the absence of a control group may reflect the improvement measurements as the natural history of the disease. Additional problems with exercise protocol studies for the treatment of exercise will be addressed later. Estlander et al. [34] performed a comprehensive 4-week physical exercise treatment program in a non-controlled study for patients with chronic low back pain. The authors noted an increase in spinal mobility and strength. Follow-up evaluations at 3 weeks and 12 months showed significant decrease in subjective disability and pain. The percentage of patients who returned to work however, was unchanged. Similar results were found in a much larger study. Approximately 12000 subjects participated in 6-week exercise program for the treatment of low back pain [35]. Approximately 81 % of the participants reported less pain based upon a 5-point pain rating scale. However, as with the above studies, there was no control group. Other studies have not proven the efficacy of exercise in the treatment of patients with low back pain. White [36] evaluated workers' compensation patients with low back pain. He found no significant benefit of exercise therapy for the relief of pain or improved function. The author
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stated that the role of patient secondary gain due to the monetary compensation system may have been a factor in the study results. Gilbert et al. [37], in a multi-centered randomized clinical trial did not show significant improvement for patients receiving manual physical therapy. The literature is mixed with regard to the utility of exercise as a treatment for low back pain. In the studies reviewed, there is no differentiation between the etiology or categorization of low back pain. Most studies have a small sample size and no control group. Therefore, the efficacy of exercise in the treatment of patients with low back pain remains questionable. Since the exercise program protocols are variable and patient compliance is often rarely assessed, it is difficult to develop exercise program standardization. Often, exercise therapy is provided by different therapists within the same exercise treatment program. The level of ability of the therapists and participants are variable. Base line physical conditioning status differs within subject groups which may affect full participation by each subject. Within many treatment protocols, home-exercise programs are prescribed where subject compliance is also a problem and difficult to monitor. The cost factor varies depending upon the duration and frequency of a particular program. Individual treatments tend to be much more expensive than group treatments; however, both usually surpass the cost of a routine physician office visit. 5. Spinal manipulation therapy One of the more controversial forms of treatment for low back pain is spinal manipulation [38-40]. The benefits of spinal manipulation may be secondary to increased joint flexibility in the areas of reduced mobility and the freeing of connective tissue adhesions. Spinal joints are passively moved or mobilized. Several authors have evaluated the many clinical trials measuring the effectiveness of manipUlation therapy for low back pain [10,40-43] and suggest that manipulation therapy may have temporary short term benefits. In a prospective randomized study [44] manipulation therapy was compared to physiotherapy, corset use or analgesic tablets in patients with low
back pain. Patients reported no significant benefit of manipulation therapy compared to the other treatments at 6-weeks, 3-months or I-year followup. Hoehler et al. [45] compared vertebral manipulation therapy with a control group receiving soft tissue massage. In a randomized clinical trial, the group receiving manipulation treatment reported an immediate significant relief after the first treatment. However at discharge, (approximately 3-4 weeks) there was no measured significant difference between groups. The authors concluded that they could not provide evidence demonstrating the long term effectiveness of manipulation therapy. Manipulation of the lumbar spine was compared to the treatment of microwave diathermy, isometric abdominal exercises and ergonomic instruction in a prospective clinical trial [46]. Patients with acute low back pain and a normal neurological examination were placed into two groups consisting of manipulation therapy and what the authors termed a standard physical therapy treatment program for the treatment and control groups, respectively. There was a significant decrease in pain duration of the manipulation treatment group. This study, however, did not evaluate the longer term effectiveness of manipulation treatment. Godfrey et al. [47] concurred with the finding of short term improvement for patients receiving manipulation therapy in a single-blind randomized clinical trial. Patients receiving manipulation therapy were compared with a control group receiving message and low level electric stimulation. There was no difference in improvement scores between these two groups. Similar to manual physical therapy and exercise programs, spinal manipulation treatment varies with practitioner technique and ability. A problem with the current research is that specific manipulation techniques utilized within a study are often poorly des.cribed. The etiology or specific diagnosis is rarely described. Except for the study by Glover [40] rarely has manipulation been scientifically shown to be a long term efficacious treatment option for patients with low back pain. Further scientific studies are needed to demon-
P.J. Marion 11. Back Musculoskelet. Rehabil. 5 (1995) 121-133
strate any long term permanent efficacy of manipulation therapy. 6. Trigger point injections
Foci of muscular spasms or irritation are often termed trigger points. These areas may cause pain resulting in stiffness and decrease strength. Trigger points are defined as a focus of tissue hyper-irritability [48]. Tenderness of this area and possible referred pain can be elicited upon palpation. Trigger points are associated with myofascial pain syndrome as a form of low back pain [49]. Garvey et al. [50], evaluated the efficacy of trigger point therapy in a prospective randomized double-blind study. A total of 63 patients were evaluated with the diagnosis of low back pain. All had a normal neurological examination. The subjects were randomly assigned into one of four treatment groups; lidocaine injection, lidocaine and steroid injection, dry needle injection or vapor coolant spray with accupressure. Outcome assessment was based on a self-reporting pain scale at the initial visit and study conclusion, but the follow-up interval time was not provided. At the study conclusion, the group which did not receive injection therapy (vapor coolantjaccupressure) reported the highest rate of improvement in pain symptoms at 66%. Both the dry needle injected and vapor coolant spray with accupressure groups reported a greater improvement in pain symptoms than the lidocaine and lidocaine and steroid injected groups. They concluded that the critical feature in pain relief from a trigger point injection was not related to the injected substance but the mechanical stimulus provided with either dry needle stick or vapor coolant spray with accupressure. In a randomized, double-blind crossover study, the effectiveness of different chemical compounds bupivacaine, etidocaine or physiological saline were evaluated as an agent in trigger point injection therapy [51]. After the injections, the subjective responses of 15 patients with myofascial pain syndrome were evaluated. The subjects reported better ratings for pain relief and muscle tension for the two anesthetic compounds versus normal saline. However, the number of patients
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were limited. The attrition rate was also not reported. This study did not address the role of trigger point injection in the specific treatment of low back pain since patients had the non-specific diagnosis of myofascial pain syndrome with or without back pain. Based on current evidence, there were no scientific studies which adequately address trigger point as an effective treatment for acute or chronic low back pain [52]. There is no standardized technique or consistent injectable compound utilized at this time for low back pain treatment. Most studies do not specifically address trigger point injections as a treatment modality specifically for low back pain. There is minimal scientific support for trigger point injection as the primary mode of low back pain treatment. As a conservative option for low back pain, treatment costs are modest yet effectiveness remains questionable. Additional studies are warranted including trigger point injection as an adjunct to exercise and medications. 7. Facet joint injection
Facet Joint Syndrome is a frequent yet nonspecific diagnosis for low back pain [53-55]. This syndrome is a poorly defined entity in which pain is thought to originate from the facet joints. The level of injection is based on the localization of the low back pain. The relief of pain by facet joint injection is considered diagnostic and therapeutic. Carrera [56] evaluated 20 patients with the diagnosis of facet joint syndrome complaining of low back pain. All patients underwent fluoroscopically guided intra-articular injection of a local anesthetic and steroid suspension. Thirteen of the 20 patients reportedly obtained immediate and complete pain relief while seven of the 13 patients reported a recurrence of back pain in less than 6 months. This study was limited in several respects. There were no control ,groups utilized. The evaluator was not blinded regarding the study outcome and there were no statistical comparisons. Carrera suggested that computer tomography has an important role in diagnosis of symptomatic facet arthropathy. Unfortunately, he also noted that this study did not
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address the efficacy of facet joint injection in the diagnosis and treatment of low back pain. Marks [57] in a prospective randomizeq comparison, evaluated the efficacy of facet joint injection and facet joint nerve block in· the diagnosis and treatment of patients with refractory chronic low back pain. There was no statistical difference for the immediate effects of facet joint injection or facet joint nerve block. Neither were there any long term differences in pain relief for either group. Marks concluded that facet joint injection or facet joint nerve block may be useful as a diagnostic tool for the diagnosis of facet joint syndrome but is of minimal benefit for the treatment in chronic low back pain. This study also suffered from the lack of a control group, no blinded outcome assessment or statistical comparisons. Jackson [58] evaluated 390 patients who suffered from localized lumbar back pain. The patients underwent intra-articular injections of local anesthetic and cortisone. Only 29% of the patients injected experienced initial pain relief. The authors determined that the facet joints were commonly not the single or primary source for low back pain in over 90% of the patients studied. This study again, could not show the efficacy of facet joint injection as a therapeutic intervention. The authors also acknowledged the lack of control group or double-blinded assessment. Lilius et al. [55] performed a prospective randomized clinical trial involving 109 patients with unilateral low back pain. The subjects were randomly assigned into three groups; cortisone and local anesthetic into two facet joints, the same mixture around two facet joints or saline into the facet joints. The subjects were evaluated at 1 h, 2 weeks and 6 weeks after treatment. They were also evaluated 3 months post-treatment. Sixty-four percent of the subjects reported initial pain relief and 36% reported continued benefit at the 3month follow-up evaluation, independent of the treatment received. Treatment outcome assessment included work attendance, pain relief and lumbar spine flexibility. The authors concluded that facet joint injection is a non-specific method of treatment and the results were secondary to the tendency for spontaneous recovery and psy-
chosocial components of back pain. The authors could not provide statistical or anecdotal evidence for facet joint injection as a useful treatment in low back pain or as a diagnostic tool. The diagnostic value and therapeutic effectiveness of facet joint injections remains controversial as a treatment option for low back pain. Diagnostic criteria has not been consistently established. This syndrome remains unclear as is the appropriate treatment. Compared to spinal epidural injections described later, a facet joint injection is the more costly of the non-surgical options for the treatment of low back pain. Proof of short term effectiveness is limited. Current evidence again has not shown facet joint injections as an effective long term treatment option for patients with low back pain. 8. Spinal epidural injections
Injection of steroid into the epidural space is the most frequently used non-surgically invasive treatment modality for low back pain. Injected epidural steroids may decrease the inflammatory component that contributes to the sciatic complaints of low back pain [59]. Benzon [60] reviewed the role of epidural steroid injections for low back pain and sciatica. He concluded that mechanical causes of low back pain, especially those accompanied by nerve root irritation, may respond to epidural steroid injections. Dilke [61] performed the first blinded prospective study of epidural injection in 1973. He reported significant effectiveness of epidural cortical steroid injection for the relief of low back pain. In a double-blind controlled trial, 100 consecutive patients were randomly assigned to a treatment (methylprednisolone and saline) or control (saline) group. Assessment outcome was based on relief of pain and resumption of normal occupation at 3-month follow-up. Approximately four times as many of the experimental subjects noted pain relief and returned to work, which was significantly better than the control group. Several authors question the effectiveness of epidural steroid injections for the treatment of low back pain. Rosen [62] retrospectively evaluated 40 patients who received epidural steroid
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injections for the treatment of low back pain and sciatica. Sixty percent of the patients reported improvement immediately after injection. Long term relief averaging 8 months was reportedly less than 25%. Fifty-three percent of the patients remained unable to return to normal activities at follow-up (average 8-month) evaluation. The authors concluded that epidural steroid injections should not be used in the long term management . of spinal stenosis or nerve root compression. They acknowledged that since this study was not double-blind and lacked a control group, there should have been a .bias toward a positive therapeutic response. Yet, the overall results showed the opposite effect. Cuckler [63] evaluated 73 patients with radicular pain in a prospective randomized double-blind study. Patients were injected with methylprednisolone acetate and procaine or saline and procaine as the control. At a 21 month average follow-up post-injection, there were no significant differences in pain relief between the experimental and control groups. They concluded that the use of epidural methylprednisolone acetate did not demonstrate any therapeutic efficacy in the treatment of acute or chronic neurocompression syndromes in the lumbar spine and was of uncertain value. White [64] evaluated 304 patients with low back pain who were injected with an epidural anesthetic and steroid under fluoroscopic guidance. The complaints of pain initially decreased dramatically but at 2 years follow-up more than 98% of the subjects reported a recurrence of low back pain. The authors concluded that epidural injections of steroids and anesthetic did not cure any of their patients and served only as a temporary relief for low back pain. During this study, the authors also noted a 25% needle placement error rate during epidural injections, which may impact treatment effectiveness. Snoek et al. [65], in a prospective double-blind study evaluated 51 patients suffering from low back pain related to herniated lumbar disc. The patients received either methylprednisolone or normal saline solution. There was no difference between the placebo and the steroid groups. Bush [66] in a prospective blinded control trial did not note a statistical significant difference at I-year
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follow-up for pain relief and mobility, except for the objective assessment of straight leg raise test for each of the two groups. Other authors [67,68] also reported that epidural injection of steroid and anesthetic may temporarily relieve low back pain and sciatica but rarely offers permanent relief. As a long term treatment of low back pain, most authors agree that the epidural injection of steroids is ineffective. Most studies do not differentiate localized low back pain versus chronic low back pain. Epidural steroid injections remains an invasive and costly technique with unsubstantiated value. 9. ChemoDucleolysis Chemonucleolysis is often characterized as a surgical procedure secondary to its significant complications and morbidity. A proteolytic enzyme, chymopapain is injected between the medial borders of the pericles and into the disc center, in order to dissolve herniated disc material [69]. Complications of chemonucleolysis have included anaphylaxis, infection, arachnoiditis and pulmonary embolism. Contra-indications include tumors, infections and metabolic etiologies of neuropathy. As outlined by McCulloch [70], appropriate selection of patients with sciatica due to herniated intervertebral disc is the single most important factor for success. A combination of patient symptoms, physical examination signs and radiological evidence must be obtained for proper patient selection. He recommended that chemonucleolysis be used only in those patients who would otherwise undergo a laminectomy or diskectomy. Evaluating the safety and efficacy of chymopapaine, Javid et al. [71] performed a double-blind randomized trial in patients diagnosed with herniated lumbar disease. The patients evaluated had prior extensive conservative therapies and were presented as candidates for laminectomy. Patients were assigned either to a placebo or chymopapain injection group. The treatment group reported significant improvement in pain at 6-months follow-up evaluation. The investigators determined that chymopapain was more effective than placebo for the treatment of patients: with herniated lumbar disc. They also suggested that
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chymopapain is an appropriate alternative for patients who are candidates for lumbar laminectomy. In a similar study Fraser [72] compared chymopapain with saline injections, in a randomized double-blind study of patients with documented lumbar disc disease. The preliminary results of this study at 6-months follow-up demonstrated a significant effect of chymopapain in the treatment of patients with disc herniation. A follow-up report [73] by Fraser evaluated the experimental and control groups 2 years post-injection. Sustained significant improvement of the chymopapain was noted in the treatment group. Fraser stressed the importance of appropriate clinical and diagnostic criteria for selecting appropriate patients for chemonucleolysis. He concluded the study by recommending chymopapain as the treatment of choice prior to consideration of disc fragment excision laminectomy. Crawshaw [74] evaluated the role of chemoneucloysis compared to surgery in the treatment of sciatica. Patients who failed to respond to conservative measures for the treatment of sciatica were placed in a chymopapain injection or surgery group. Subjects were assessed at 1 month, 3 months and 1 year. The failure rate in the chymopapain group was approximately 50%, compared to 11 % for the surgical group. The authors concluded that chemonucleolysis may be an appropriate step after the failure of conservative treatment prior to surgery but that chymopapain treatment failure should be immediately identified in order to pursue surgical options which may improve the surgical success rate. A 10-year follow-up evaluation compared chemonucleolysis to open discsectomy [75]. Both groups had a similar rate of re-operation and there was no difference of pain outcome measures. Chemonucleolysis procedures are now performed less frequently secondary to the inconsistent resultants, complications and morbidity. As treatment options become more aggressive and invasive, appropriate diagnostic criteria and patient selection are especially pertinent. Positive outcomes have been shown for appropriate patients undergoing chemoneucleolysis. Approximatelya reported 15% of patients do not respond
to chemonucleolysis and require further surgical intervention [71]. However, due to neurological complications, an allergic reaction rate of 0.5% and a 20% rate of persistent muscle spasms [5] it has more recently become less of a treatment option. 10. Surgery
The surgical treatment of low back pain and sciatica is usually indicated when a patient presents with a marked neurological deficit such as motor weakness, foot drop, bowel and bladder symptoms or unrelenting leg pain. A small percentage of patients who have a herniated disc, not resolved with conservative measures, may require surgery [76]. Proper selection of patients is critical for a successful outcome. Poor outcomes are related to lack of valid selection criteria, inaccurate diagnosis or psychological overlay [5]. Thomas et al. [77] compared the results of 86 patients with low back pain receiving surgical laminectomy to 32 patients receiving conservative treatment. Their criteria for surgical treatment were; one attack of low back pain and/or sciatica associated with loss of time from work and a filling defect on a myelogram. Patients undergoing surgical treatment had a laminectomy with removal of protruded disc material. Outcome was based on a non-blinded subjective 4-point scale. The authors concluded from the results of their questionnaire that laminectomy was an effective treatment for many patients who failed conservative efforts. They stressed that surgery must be provided earlier to improve outcome. Patients undergoing surgery who had symptoms for < 1 year improved at a rate of 81 % compared to patient having symptoms > 10 years with a 41 % improvement rate. Frymoyer et al. [78] evaluated the results of patients who underwent lumbar disc surgery in a lO-year follow-up study. The long term results of patients undergoing disc excision alone was compared to those undergoing disc excision with primary posterior midline surgical vertebral fusion. All patients evaluated were at least 10 years post-surgical procedure, averaging approximately 14 years. There were no statistical pre-operative
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symptom differences for each group. The study noted unsatisfactory results in approximately one third of the patients who had either surgical procedure at 10-year follow-up. A study by Weber [79] compared surgery with non-surgery treatments at 1-, 4- and 10-year follow-up. He noted significant improvement in the surgically treated group at the I-year follow-up examination. At 4 years and 10 years, there was no significant improvement noted for the surgical group. The outcome for patients receiving surgery for the treatment of low back pain are at best mixed. As emphasized by Frymoyer [5], appropriate patient selection is crucial for optimal outcome. Patients with marked neurological deficits are most appropriate for surgical intervention. Given the cost and risk of significant post-operative morbidity, a trial of conservative therapy should be tried initially. 11. Summary Since the etiology of low back pain can be complex, the specific etiologies are rarely separated for investigation. Including the studies reviewed, rarely are the etiologies discussed, categorized by location, type of symptoms, diagnosis or symptom duration. There continues to be no single clinically proven superior treatment for low back pain. This may explain the multiplicity of treatments available. The scope of this article and the limited number of rigorous scientific studies did not permit the inclusion of physical modalities such as heat, cold, ultrasound or electrical stimulation. It has been suggested that transcutaneous electrical nerve stimulation (TENS; another modality), is no more effective than placebo [80,81]. Only nine of the more common treatments were addressed in th\s review article. The conventional treatment for low back pain continues to be the triad of rest, analgesic medication and perhaps exercise after the acute phase of low back pain. The treatment triad of bed rest, analgesics with or without exercise remains the least costly option. None of the remaining treatment options evaluated in this review were consistently shown to be more effective than this traditional
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triad treatment course. Many of the procedures outlined may have a role, yet unproven for the immediate treatment of low back pain. The longer term effectiveness of epidural steroid injection or facet block for low back pain remains doubtful. In the majority of patients with complaints of low back pain, surgery is not indicated. Surgery for the treatment of low back pain is reserved for those patients who have progressive neurological deficits or severe intractable pain. For those patients who have neurological deficits and a documented lesion surgery can be an immediate and appropriate treatment. The specific type of surgery chosen; laminectomy, fusion or chemonucleolysis and their appropriate indications are still debated. Given the frequency of low back pain and its resultant economic toll, further studies including valid functional outcomes measures are desperately needed. References [1] Nachemson AL: The lumbar spine: an orthopedic challenge. Spine 1976;1(1):59-71. [2] Barton J, Haight RO, Marslan DWet al.: Low back pain in the primary care setting. J Fam Pract 1976;3:363-366. [3] Snook SH: The cost of back pain in industry. Spine State Art Rev 1987;2:1-5. [4] Abenhaim L, Subsa S: Importance and economic burden of occupational low back pain: a study of 2500 cases. J Occup Med 1987;29:670-671. [5] Frymoyer JW: Back pain and sciatica. N Engl J Med 1988;318(5):291-300. [6] Vukmir RB: Low back pain. Am J Emerg Med 1991;9:328-335. [7] Fast A: Low back disorders: conservative management. Arch Phys Med Rehabil 1988;69:880-891. [8] Borenstein D: Epidemiology, etiology, diagnostic evaluation, and treatment of low back pain. Curr Opin RheumatoI1992;2:226-232. [9] Cavin MB, Wiesel SW: Low back pain. Curr Opin RheumatoI1991;3:65-70. [10] Deyo R: Conservative therapy for low back pain: distinguising useful from useless therapy. JAmMed Assoc 1983;250(8): 1057-1062. [11] Allis W: The 1993 Physicians' Fee Reference, 10th edn. Wasserman, New York, 1993. [12] Nachemson AL: The influence of spinal movements on the lumbar intradisc pressure and on the tensile stresses in the annulus fibrosis. Acta Orthop Scand 1963;183-207. [13] Nachemson AL, Morris JM: In vivo measurements of intradiscal pressure: discometry, a method for the de-
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[14] [15] [16] [17] [18] [19] [20] [21] [22] [23]
[24] [25] [26]
[27] [28] [29] [30] [31] [32] [33]
P.J. Marion /1. Back Musculoskelet. Rehabil. 5 (1995) 121-133 termination of pressure in the lower lumbar discs. J Bone Joint Surg 1964;46A:1077-1092. Wiesel SW, Cuckler JM, DeLuca F et al.: Acute low back pain: an objective analysis of conservative therapy. Spine 1980;5:324-330. Deyo RA, Diehl AI
