J Manipulative Physiol Ther 2014 (Mar); 37 (3): 155-163 ~ FULL TEXT
Serafin Leemann, DC, Cynthia K. Peterson, RN, Christof Schmid, DC,
Bernard Anklin, DC, B. Kim Humphreys, DC, PhD
Professor, Chiropractic Medicine and Radiology departments,
Orthopaedic University Hospital Balgrist,
University of Zürich, Zürich, Switzerland.
This study, from the chiropractic researchers at the University of Zurich in Switzerland, demonstrates long-term benefits from chiropractic adjustments for lumbar disc herniations, and another study by the same group finds that chiropractic helps low back pain during pregnancy.
Objective The purposes of this study were to evaluate patients with low-back pain (LBP) and leg pain due to magnetic resonance imaging–confirmed disc herniation who are treated with high-velocity, low-amplitude spinal manipulation in terms of their short-, medium-, and long-term outcomes of self-reported global impression of change and pain levels at various time points up to 1 year and to determine if outcomes differ between acute and chronic patients using a prospective, cohort design.
Methods This prospective cohort outcomes study includes 148 patients (between ages of 18 and 65 years) with LBP, leg pain, and physical examination abnormalities with concordant lumbar disc herniations. Baseline numerical rating scale (NRS) data for LBP, leg pain, and the Oswestry questionnaire were obtained. The specific lumbar spinal manipulation was dependent upon whether the disc herniation was intraforaminal or paramedian as seen on the magnetic resonance images and was performed by a doctor of chiropractic. Outcomes included the patient’s global impression of change scale for overall improvement, the NRS for LBP, leg pain, and the Oswestry questionnaire at 2 weeks, 1, 3, and 6 months, and 1 year after the first treatment. The proportion of patients reporting “improvement” on the patient’s global impression of change scale was calculated for all patients and acute vs chronic patients. Pretreatment and posttreatment NRS scores were compared using the paired t test. Baseline and follow-up Oswestry scores were compared using the Wilcoxon test. Numerical rating scale and Oswestry scores for acute vs chronic patients were compared using the unpaired t test for NRS scores and the Mann-Whitney U test for Oswestry scores. Logistic regression analysis compared baseline variables with “improvement.”
Results Significant improvement for all outcomes at all time points was reported (P < .0001). At 3 months, 90.5% of patients were “improved” with 88.0% “improved” at 1 year. Although acute patients improved faster by 3 months, 81.8% of chronic patients reported “improvement” with 89.2% “improved” at 1 year. There were no adverse events reported.
Conclusions A large percentage of acute and importantly chronic lumbar disc herniation patients treated with chiropractic spinal manipulation reported clinically relevant improvement.
Key Indexing Terms: Intervertebral Disc Displacement, Lumbar Vertebrae Manipulation, Spinal, Chiropractic
From the Full-Text Article:
Approximately 70% of the population will have back pain at some point in time.1 Low-back pain (LBP) with associated leg pain due to a herniated intervertebral disc is one of the most severe and disabling forms of back pain. [1–4] Many treatment options are available that can be grouped into 2 categories: surgical and conservative care. Conservative care may include medication, corticosteroid nerve root or epidural infiltrations, bed rest, physical therapy, flexion/distraction therapy, and spinal manipulation.
The first meta-analysis comparing the effectiveness of spinal manipulative therapy (SMT) for LBP patients with disc herniations with other therapies concluded that SMT was neither more nor less effective than other kinds of conservative care.  Although a later systematic review concluded that SMT is a very safe and cost-effective option for treating symptomatic lumbar disc herniation (LDH), little research was cited to support that conclusion.  A 2006 randomized controlled trial (RCT) comparing active SMT with simulated SMT in disc herniation patients showed that patients treated with active SMT had greater pain relief and consumed fewer drugs compared with those receiving the simulated SMT.  However, only disc herniations with an intact peripheral annulus were included. A later systematic review as well as an extensive literature synthesis also evaluating the effectiveness of conservative treatments for patients with lumbar radiculopathy stated that no conclusion could be drawn whether physical therapy, medication, bed rest, or manipulation should be prescribed. [8, 9]
A recent pilot study evaluated chronic lumbar disc herniation patients having radiculopathy for over 3 months who had failed 3 months of nonoperative and non-SMT treatment. These patients were randomly assigned to receive SMT or microdiskectomy.  Although 60% of the patients benefited from SMT to the same degree as those having surgical intervention, it is hard to determine precisely what was considered “benefit” in this study as, although many valid outcome measures were used, it is not specifically stated what was the primary outcome measure and how much change was considered “benefit.” It appears that any improvement from baseline was considered a benefit. The most recent systematic review evaluating both manipulation and mobilization as treatments for patients having radiculopathy stated that there is moderate evidence that SMT is better than sham SMT in the short and long terms but that the evidence comparing SMT with other therapies is of low quality. 
Despite the fact that there is only moderate evidence in the literature supporting the use of spinal manipulation to treat LDH, it is widely used by manual therapists.  Therefore, the purposes of this study are
(1) to evaluate patients with LBP and leg pain due to magnetic resonance imaging (MRI)–confirmed disc herniation who are treated with high-velocity, low-amplitude spinal manipulation in terms of their short-, medium-, and long-term outcomes of self-reported global impression of change and pain levels at various time points up to 1 year and
(2) to determine if outcomes differ between acute and chronic patients using a prospective, cohort design.
The purpose of this study was to document outcomes of patients with confirmed, symptomatic lumbar disc herniations and sciatica who were specifically treated with side posture high-velocity, low-amplitude, spinal manipulation to the level of the disc herniation. It is important to emphasize that all patients in this study had clear abnormal physical examination findings of radiculopathy, as described in the methods section, corresponding to their MRI abnormalities. Although previous studies have identified the presence of “leg pain” in addition to LBP as a negative prognostic factor for improvement with chiropractic treatment compared with patients with LBP only, a recent, large, prospective outcome study found that the presence of radiculopathy was not a negative predictor of improvement in LBP patients being treated with chiropractic therapy. [14, 17, 18]
The proportion of patients reporting clinically relevant improvement in this current study is surprisingly good, with nearly 70% of patients improved as early as 2 weeks after the start of treatment. By 3 months, this figure was up to 90.5% and then stabilized at 6 months and 1 year. One may argue that most of the treatment effect is explained by natural history. This might contribute significantly to the outcomes in the acute patient subgroup. However, for the chronic patients, any positive effect due to natural history should already have occurred. The natural history of sciatica in acute disc herniation patients is normally quite favorable, with 36% reporting major improvement after 2 weeks and up to 73% having resolution of their leg pain by 12 weeks. [19, 20] The acute patients in this current study reported more substantial improvement and improved more quickly than the chronic patients, with more than 80% reporting clinically relevant improvement as early as 2 weeks and 94.5% improved at 3 months. These results are better than the natural history figures cited above. [19, 20]
Even the chronic patients in this study, with the mean duration of their symptoms being over 450 days, reported significant improvement, although this takes slightly longer. More than 81% reported being “improved” at 3 months, and the proportion reporting “improvement” at 1 year (89.2%) was slightly higher than the percentage for acute patients. This was due to the higher number of acute patients reporting a recurrence. In addition, the LBP NRS levels for chronic patients significantly dropped from a baseline mean of 5.78 to 2.08 at 3 months, and their leg pain decreased from 4.56 at baseline to 0.88 at 3 months. This cannot be explained by natural history as a previous study found that duration of symptoms more than 30 days was predictive of an unfavorable outcome, at 3 months after start of treatment.  The results from this current study are better than the 60% of chronic patients who benefited from side posture SMT at 12 weeks reported by McMorland et al,  better than the 50% of chronic patients reporting improvement in an article by Cassidy et al,  and better than the 59% of subacute and chronic patients reporting success after manipulation by Petersen et al  The results in this current study are encouraging when considering that it is chronic LBP patients who are a large economic burden with greater use of prescription medications and increased use of other health care resources. 
Unfortunately, recurrences cannot be avoided completely because the genesis of this condition is multifactorial. In the acute patient group, 11 patients reported a recurrence between the 6-month and 1-year data collection periods. No chronic patients reported a recurrence however. A small proportion of patients reported being “worse” after the start of treatment with 2.1% of 137 patients reporting that they were “slightly worse” or “worse” at 3 months and 2.8% of patients reporting that they were “slightly worse” at 1 year. No patient reported being “much worse.” One topic that needs to be addressed is the often stated fear that SMT applied to patients with disc herniation often causes cauda equina syndrome. [6, 24] No cases of cauda equina syndrome or other serious adverse events were reported in this current study. Three patients did choose to have surgery, however, although they had reported significant improvement at 1 month, and one patient elected to have an epidural injection of anesthetic and corticosteroid.
It was not surprising that there were few predictors of “improvement” identified from the baseline variables as previous studies have also struggled to find reliable predictors of improvement in LBP patients. [14, 18] However, chronicity of complaint was a predictor for early improvement with acute patients having better outcomes at 2 weeks, most likely due to the natural history of this condition as previously mentioned. Although patients reporting higher levels of leg pain at baseline were less likely to improve at 2 weeks, this factor was no longer predictive at all follow-up time points. This information is useful for patients as well as the clinicians treating these patients. Surprisingly, the baseline OPDQ total score was not prognostic for improvement until the 3- and 6-month time points with higher baseline scores associated with an increased likelihood of improvement. Certainly, acute patients have higher baseline disability and pain scores compared with chronic patients and improve more quickly than chronic patients as noted above, so this may be one reason for this result. However, it does not explain why the OPDQ was not prognostic until later in the course of the condition. Not until it was placed into the logistic regression model, controlling for other factors, did it became predictive.
The major criticism of this study may be that it is not an RCT using a control group which had no treatment. Although RCTs are traditionally the criterion standard for determining effective treatments, there has been recent criticism of this research methodology pointing out that their strict inclusion and exclusion criteria may result in study populations that do not represent real-world conditions, and thus, the results may be of limited use to clinicians and not generalizable to the intended population. [25, 26] However, pragmatic RCTs, which use a broader selection criteria and observational studies, as in this prospective outcomes study, can include large and diverse populations and are more likely to reflect the patients routinely seen in clinical practice. The inclusion/exclusion criteria (and therefore the participants) in this study are no different from those that would be recruited in an RCT to address the same study hypotheses.
Treatment in this current study was standardized to 1 of the 2 possible manipulative procedures, based on the location of the disc herniation as seen on the MRI scans. Furthermore, patients whose herniations had penetrated through the peripheral annular fibers, the posterior longitudinal ligament or were sequestered were not excluded from being treated with SMT as was done in the RCT by Santilli et al  However, no studies have been conducted to determine whether there is a difference in outcome based on the choice of the specific manipulative procedure or the type and location of disc herniation.
The hypothetical rationale behind selecting one SMT procedure over the other based on the MRI and clinical findings is based on the mechanics of each lesion. First, by combined flexion and lateral bending, the side on which the patient lies is determined because it is not desired to treat into the pain. For foraminal hernias, it is preferred to gap the foramen on the affected side thereby inducing more normal movement patterns, decreasing the pressure on the disc and nerve, releasing adhesions, allowing efflux of chemical irritants, and stimulating the receptors in the surrounding tissues. For paramedian hernias, it is the unaffected side but with the same therapeutic goals in mind. The opening of the foramen seems to be of lesser importance for these disc herniations. Of course, this is all hypothetical and needs to be investigated further.
As this is a cohort outcomes study rather than an RCT means that the outcomes cannot be directly attributed to the SMT treatment. Additional research comparing SMT with other treatments, for example, therapeutic nerve root infiltrations needs to be done. All patients were examined and treated in a single chiropractic practice in Zürich, Switzerland using a standardized treatment approach. Therefore, the results obtained may not be representative of other chiropractic practices. The relatively small sample size for the subgroup of disc herniation patients whose symptoms were “chronic” (37 patients) is another limitation.
A large percentage of acute and importantly chronic lumbar disc herniation patients treated with high-velocity, low-amplitude side posture SMT reported clinically relevant “improvement” with no serious adverse events.
A large proportion of patients with symptomatic, MRI-confirmed,
lumbar disc herniations reported statistically significant and
clinically relevant improvement in all outcome measures
as early as 2 weeks after start of treatment.
The percentage of patients reporting clinically relevant improvement
continued to increase up to 3 months after the first treatment and
then stabilized up to the 1-year time point.
More than 80% of chronic lumbar disc herniation patients who had
symptoms over 3 months reported clinically relevant “improvement”
at 3 and 6 months and 1 year after receiving chiropractic SMT.
There were no adverse events reported due to SMT applied to the patients
with MRI-confirmed, symptomatic lumbar disc herniations.