Given our limited ability to isolate causative sources of chronic lower back pain, there is a little consensus with regard to a definitive treatment approach. Substantial variation in management by conservative and invasive approaches exists between practitioners throughout the country [8]. We will briefly describe these treatment options for the management of chronic low back pain syndromes within each of the four primary categories: physical therapy (and associated modalities and behavioral techniques), pharmacotherapy, injection therapy, and surgical intervention.
Exercise-based and behavioral interventions
Exercise therapy
Exercise therapy (ET) remains one of the conservative mainstays of treatment for chronic lumbar spine pain, and may be tailored to include aerobic exercise, muscle strengthening, and stretching exercises [49]. Significant variation in regimen, intensity, and frequency of prescribed programs presents challenges to assessing efficacy among patients [50]. One meta-analysis of the current literature exploring the role of ET in patients with varying duration of symptoms found a graded exercise program implemented within the occupational setting demonstrated some effectiveness in subacute LBP. Among those suffering chronic pain symptoms, small, but statistically significant improvements were observed among patients, with regard to pain reduction and functional improvement [49]. The optimal approach to exercise therapy in chronic low back pain sufferers appears to be those regimens involving an individually-designed exercise program emphasizing stretching and muscle strengthening, administered in a supervised fashion, with high frequency and close adherence. Such results are complemented by other conservative approaches, including NSAIDS, manual therapies, and daily physical activity [50].
Transcutaneous electrical nerve stimulation (TENS)
A “TENS” unit is a therapeutic modality involving skin surface electrodes which deliver electrical stimulation to peripheral nerves in an effort to relieve pain noninvasively. Such devices are frequently available in outpatient exercise therapy settings, with up to a third of patients experiencing mild skin irritation following treatment [51]. While one small study identified an immediate reduction in pain symptoms 1 h following TENS application, there remains little evidence of long-term relief. Another larger study did not discover significant improvement with TENS compared with placebo with regard to pain, functional status, or range of motion [52, 53].
Back school
Back School was introduced first in Sweden with the purpose of minimizing lower back pain symptoms and their reoccurrence through review with patients of lumbar anatomy, concepts of posture, ergonomics, and appropriate back exercises [54]. Two meta-analyses concluded that there is moderate evidence for improvement in both pain and functional status for chronic low back pain within short and intermediate time courses, when measured against other modalities such as exercise, joint manipulation, myofascial therapy, and/or other educational therapy [52, 54].
Lumbar supports
Lumbar back supports may provide benefit to patients suffering chronic LBP secondary to degenerative processes through several potential, debated mechanisms. Supports are designed to limit spine motion, stabilize, correct deformity, and reduce mechanical forces. They may further have effects by massaging painful areas and applying beneficial heat; however, they may also function as a placebo. There is moderate available evidence evaluating efficacy of lumbar supports within a mixed population of acute, subacute, and chronic LBP sufferers to suggest that lumbar supports are not more effective than other treatment forms; data is conflicting with regard to patient improvement and functional ability to return to work [52].
Traction
Lumbar traction applies a longitudinal force to the axial spine through use of a harness attached to the iliac crest and lower rib cage to relieve chronic low back pain. The forces, which open intervertebral space and decrease spine lordosis, are adjusted both with regard to level and duration and may closely be measured in motorized and bed rest devices. Temporary spine realignments are theorized to improve symptoms related to degenerative spine disease by relieving mechanical stress, nerve compression, and adhesions of the facet and annulus, as well as through disruption of nociceptive pain signals [52]. Nonetheless, patients with chronic symptoms and radicular pain have not found traction to provide significant improvement in pain nor daily functioning [55–57]. Little is known with regard to the risks associated with the applied forces. Isolated case reports cite nerve impingement with heavy forces, and the potential for respiratory constraints or blood pressure changes due to the harness placement and positioning [52].
Spine manipulation
Spine manipulation is a manual therapy approach involving low-velocity, long lever manipulation of a joint beyond the accustomed, but not anatomical range of motion. The precise mechanism for improvement in low back pain sufferers remains unclear. Manipulative therapy may function through: “(1) release for the entrapped synovial folds, (2) relaxation of hypertonic muscle, (3) disruption of articular or periarticular adhesion, (4) unbuckling of motion segments that have undergone disproportionate displacement, (5) reduction of disk bulge, (6) repositioning of miniscule structures within the articular surface, (7) mechanical stimulation of nociceptive joint fibers, (8) change in neurophysiological function, and (9) reduction of muscle spasm” [58].
Available research regarding its efficacy in the context of chronic LBP finds spinal manipulation to be “more effective” compared to sham manipulation with regard to both short- and long-term relief of pain, as well as short-term functional improvement [52]. Compared with other conventional, conservative treatment approaches such as exercise therapy, back school, and NSAID prescription, spinal manipulation appears comparable in its effectiveness both in short- and long-term benefits [52, 59]. Research exploring the safety of such therapy among trained therapists found a very low risk of complications, with clinically worsened disk herniation or cauda equina syndrome occurring in fewer than 1/3.7 million [60].
Massage therapy
Massage therapy for chronic LBP appears to provide some beneficial relief. Weighed against other interventions, it proved less efficacious than TENS and manipulation, comparable with corsets and exercise regimens, and superior to acupuncture and other relaxation therapies, when followed over a 1-year course. Such preliminary results need confirmation, and evaluation for cost-effectiveness, but nevertheless suggest a potential role in certain, interested patients [61].
Multidisciplinary back therapy: the bio-psychosocial approach
Psychopathology is well recognized for its association with chronic spinal pain, and, when untreated, its ability to compromise management efforts [25]. For this reason, patients may find relief through learned cognitive strategies, termed “behavioral”, or “bio-psychosocial” therapy. Strategies involving reinforcement, modified expectations, imagery/relaxation techniques, and learned control of physiological responses aim to reduce a patient’s perception of disability and pain symptoms. To date, evidence is limited with regard to the efficacy of operant, cognitive, and respondent treatment approaches [52].
Pharmacotherapy
Treatment efforts to control pain and swelling, minimize disability, and improve the quality of life with lumbar spondylosis often require medication to complement nonpharmacologic interventions. Extensive research efforts have explored the efficacy of different oral medications in the management of low back pain secondary to degenerative processes. Nonetheless, there remains no clear consensus regarding the gold-standard approach to pharmacologic management [62].
NSAIDS
NSAIDS are widely regarded as an appropriate first step in management, providing analgesic and anti-inflammatory effects. There is adequate data demonstrating efficacy in pain reduction in the context of chronic low back pain [63–66], with use most commonly limited by gastrointestinal (GI) complaints. COX2 inhibitors offer modest relief in chronic LBP and improved function in the long-term setting. While they elicit fewer GI complications, their utilization has been curbed due to evidence for increased cardiovascular risk with prolonged use [52].
Opioid medications
Opioid medications may be considered as an alternative or augmentive therapy for patients suffering from gastrointestinal effects or poor pain control on NSAID management. The practice of prescribing narcotics for chronic low back pain sufferers is extremely variable within practitioners, with a range of 3–66% of chronic LBP patients taking some form of opioid in various literature studies [67]. These patients tend to report greater distress/suffering and higher functional disability scores [68, 69]. Two meta-analyses suggest a modest short-term benefit of opioid use for treatment of chronic LBP while issuing a warning regarding the limited quality of available studies and the high rate of tolerance and abuse associated with long-term narcotic use within this patient population [62, 67].
Antidepressants
The use of antidepressants for treatment of LBP symptoms has also been explored considerably given their proposed analgesic value at low doses, and dual role in treatment of commonly comorbid depression that accompanies LBP and may negatively impact both sleep and pain tolerance [52]. Two separate reviews of available literature found evidence for pain relief with antidepressants, but no significant impact on functioning [70, 71].
Muscle relaxants
Muscle relaxants, taking the form of either antispasmodic or antispasticity medications, may provide benefit in chronic low back pain attributed to degenerative conditions. There remains moderate to strong evidence through several trials comparing either a benzodiazepine, or non-benzodiazepine with placebo that muscle relaxants provide benefit with regard to short-term pain relief and overall functioning [52, 62, 72].
Injection therapy
Epidural steroid injections
Epidural steroid injections (ESI) have become a common interventional strategy in the management of chronic axial and radicular pain due to degeneration of the lumbar spine. These injections may be performed through interlaminar, transforaminal, or caudal approaches. Usually by way of needles guided under fluoroscopy, contrast, then local anesthetic and steroid are infused into the epidural space at the target vertebral level and bathe exiting nerve roots. Symptomatic relief is theorized to occur through complementary mechanisms. Local anesthetics provide quick diagnostic confirmation, and therapeutically may short circuit the “pain spasm cycle” and block pain signal transmission [73]. Corticosteroids are well recognized for their capacity to reduce inflammation through blockade of pro-inflammatory mediators.
Within the span of less than one decade (1998–2005), the number of ESI procedures performed has increased by 121% [73]. Despite this widespread utilization, controversy remains regarding the efficacy of these injections, fueled by the expense and the infrequent but potential risks related to needle placement and adverse medication reactions. Available published data cites wide ranges in reported success rates due to variation in study designs, distinct procedural techniques, small cohorts, and imperfect control groups [74]. For example, prior to the year 2000, few efficacy studies of lumbar ESI utilized fluoroscopy to establish appropriate needle position. Research suggests that without fluoroscopic guidance confirmation, needle position may be inappropriate in as frequently as 25% of cases, even with experienced providers [75]. Review articles and practicing clinicians alike must interpret such methodological differences between studies to assemble opinions on efficacy and utility of ESI for LBP treatment.
One such review exploring efficacy of interlaminar lumbar injections concluded strong evidence for short-term pain relief and limited benefit for long-term benefit [73] citing, among many, randomized controlled trials (RCT) by Arden and Carette of unilateral sciatic pain, finding statistically significant improvement in up to 75% of patients with steroid/anesthesia versus saline injections at 3 weeks, with benefit waning by 6 weeks and 3 months, respectively [76, 77].
The same review evaluating the transforaminal injection approach to unilateral sciatica found strong evidence for short-term, and moderate evidence for long-term symptom and functional improvement, based on the findings from several RCT. Vad et al. [78] studied 48 patients with herniated nucleus pulposus or radicular pain, treated with transforaminal ESI versus trigger point injections, citing an 84% improvement in functional scoring compared with 48% in the control group, extending for a follow-up period of 1 year. Lutz et al. [79] treated and followed a different cohort of 69 patients with the same underlying diagnoses, with transforaminal ESI for 80 weeks demonstrating 75% of patients with a successful long-term outcome, defined as >50% reduction in pain scores. In spinal stenosis, transforaminal ESI has achieved >50% pain reduction, improved walking, and improved standing tolerance in symptomatic patients extending through 1 year follow-up [80]. Furthermore, prospective trials by Yang and Riew found patients with severe lumbar radiculopathies and spinal stenosis treated with transforaminal injections experienced such sustained functional and symptomatic benefits so as to avoid intended surgical intervention [81–83].
Facet injections
Facet joints, also termed zygapophysial joints, are paired diarthrodial articulations between adjacent vertebrae. These joints are innervated from the medial branches of the dorsal rami and, through anatomical studies, possess free and encapsulated nerve endings, mechanoreceptors, and nociceptors. Inflammation to the joint creates pain signals which are implicated in 15–45% of patients with low back pain [25].
Diagnostic blocks of the joint inject anesthesia directly into the joint space or associated medial branch (MBB). Systematic reviews of both retrospective and prospective trials reveal single diagnostic facet blocks carry a false-positive rate of 22% to 47% [84] and medial branch blocks of 17–47% in the lumbar spine [85].
Subsequent therapeutic injections are similarly performed through either approach, with systematic reviews concluding moderate evidence available for short-term and long-term pain relief with facet blocks [86]. This evidence stems from studies such as Fuch’s RCT showing significant pain relief, functional improvement, and quality of life enhancement at 3 and 6 month intervals [87]. By contrast, Carette et al. [88] found no meaningful difference in perceived benefit between patients treated with steroid versus saline (control) injection at 3 and 6 month intervals. Available literature of MBB similarly show moderate evidence for short- and long-term relief [86] based on RCT of MBB under fluoroscopy, showing significant relief (by means of pain relief, physical health, psychological benefit, reduced narcotic intake, and employment status), with 1–3 injections in 100% patients at 3 months, 75–88% at 6 months, and 17–25% at 1 year [89].
SI joint injections
The sacroiliac joint space is a diarthrodial synovial joint with debated innervation patterns that involve both myelinated and unmyelinated axons. Injury or inflammation at the joint creates pain signals which are implicated in 10–27% of patients with low back pain [25] and may also refer to the buttocks, groin, thigh, and lower extremities.
There is moderate evidence to support the use of both diagnostic and therapeutic blocks of the SI joint [25]. Pereira treated 10 patients with MRI-guided bilateral SI joint injections of steroid, eight of whom reported “good to excellent” pain relief persisting through 13 months follow-up [90]. Maugers compared corticosteroid versus placebo injections under fluoroscopic guidance in SI joints of 10 symptomatic patients, reporting patient benefit only in the corticosteroid group. That benefit waned slowly over time, from 70% of patients at 1 month, to 62% at 3 months, and 58% at 6 months [91]. At this point, there is limited evidence to support radiofrequency neurotomy (ablation procedure) of the SI joint [92].
A recent meta-analysis provided the following guiding principles with regard to the frequency these procedures should be implemented in clinical practice. In cases of ESI, facet, and sacroiliac injections, diagnostic injections should be considered at intervals of no sooner than 1–2 weeks apart. Therapeutic injections may be performed at most every 2–3 months, provided the patient experiences greater than 50% relief within 6 weeks. Injections should be performed only as they are medically necessary given their associated risks and significant costs [25].
Intradiscal nonoperative therapies for discogenic pain
Discogenic pain has been identified as the source in 39% of patients with chronic low back pain. As described above, a cascade of effects induces the changes in the disk which generate pain. Discography seeks, when noninvasive imaging has failed, to identify damaged disks through injection of fluid into disk levels, in an attempt to reproduce patient symptoms. The technique’s utility remains controversial given significant potential for false positives. Provoked pain may be alternatively represent central hyperalgesia, reflect the patient’s chronic pain or psychological state, or result from technical difficulty due to the procedure itself [93].
If a diseased disk is identified, several treatment options exist. In addition to surgical correction, there are minimally invasive options. Both Intradiscal electrothermal therapy (IDET) and Radiofrequency posterior annuloplasty (RPA) involve electrode placement into the disk. Heat and electrical current coagulate the posterior anulus, and in doing so, strengthen collagen fibers, seal figures, denature inflammatory exudates, and coagulate nociceptors [25]. Current evidence provides moderate support for IDET in discogenic pain sufferers. Preliminary studies of RPA provide limited support for short term relief, with indeterminate long-term value. Both procedures have associated complications, including catheter malfunction, nerve root injuries, post-procedure disk herniation, and infection risk [25].
Surgical options
Surgical interventions are generally reserved for patients who have failed conservative options. Patients must be considered as appropriate “surgical candidates,” taking into consideration medical comorbidities as well as age, socioeconomic status, and projected activity level following a procedure [18]. Many surgical approaches have been developed to achieve one of the two primary goals: spinal fusion or spine decompression (or both).
Spinal fusion is considered in patients with malalignment or excessive motion of the spine, as seen with DDD and spondylolisthesis. Several surgical fusion approaches exist, all involving the addition of a bone graft to grow between vertebral elements to limit associated motion. Decompression surgery is indicated for patients with clear evidence of neural impingement, correcting the intrusion of bone or disk as might be seen in spinal or foraminal stenosis, disk herniation, osteophytosis, or degenerative spondylolisthesis. Despite dramatic increases in the number of procedures performed over the last several decades, there remains controversy as to the efficacy of these procedures in resolving chronic low back unresponsive to conservative management.
Controversy arises, in part, due to the inherent challenges of comparing the available research. Systematic reviews cite the heterogeneity of current trials which evaluate different surgical techniques with differing comparison groups and limited follow-up, frequently without patient-centered or pain outcomes included [18]. Some case series reveal promising results [94]. Nonetheless, a recent meta-analysis of 31 randomized controlled trials, concluded, “[there is] no clear evidence about the most effective technique of decompression for spinal stenosis or the extent of that decompression. There is limited evidence that adjunct fusion to supplement decompression for degenerative spondylolisthesis produces less progressive slip and better clinical outcomes than decompression alone.” Another review, noting no statistically significant improvement in patients undergoing fusion compared with nonsurgical interventions commented, “surgeons should recommend spinal fusion cautiously to patients with chronic low back pain. Further long-term follow-ups of the studies reviewed in this meta-analysis are required to provide more conclusive evidence in favor of either treatment” [95].