By David Kiefer, MD
Synopsis: Men with low back pain who received one high-velocity, low-amplitude spinal manipulation had less pain and improvements in disc space and hip and spinal flexion.
Source: Vieira-Pellenz F, et al. Short-term effect of spinal manipulation on pain perception, spinal mobility, and full height recovery in male subjects with degenerative disk disease: A randomized, controlled trial. Arch Phys Med Rehabil 2014;95:1613-1619.
- This randomized, controlled study examined the use of high-velocity, low-amplitude spinal manipulation in 40 men with low back pain from degenerative disc disease.
- After one high-velocity, low-amplitude thrust, men in the treatment group had a statistically significant improvement in pain, disc space, and hip and spinal flexion.
Spinal manipulation, practiced most commonly by osteopathic physicians, physical therapists, and chiropractors, has been studied for its effect on low back pain of various etiologies. The researchers of this trial attempt to add to the literature on spinal manipulation, which they claim is “sparse” and “conflicting,” through this randomized, controlled trial. In addition, their methodology aimed to determine a mechanism of action, or “neural mechanosensitivity response,” through straight leg testing.
The particular type of spinal manipulation examined in this trial is a high-velocity, low-amplitude (HVLA) approach, with thrusts of movement that characteristically create a “pop” to move a specific joint. The researchers randomized 40 men with low back pain to either one HVLA treatment (n = 20) or a control treatment (n = 20), the latter involving similar positioning and time of treatment with no thrust delivered. The men had to have low back pain of category 1 or 2 severity as per Quebec Task Force classification, and magnetic resonance imaging (MRI) of intervertebral disc degenerative in the lumbosacral region. There was a long list of exclusion criteria (see Table 1). The immediate effect of the HVLA was evaluated by measuring study participant’s height (an indirect indicator of intervertebral disc space), self-perceived low back pain, neural mechanosensitivity as determined by passive straight leg raise range of motion, spinal flexion mobility (forward bend, “finger-to-floor” measurement, with a lower number meaning closer to the floor), and a stadiometer to measure intervertebral disc compression. A stadiometer is a device that can accurately measure height, and by default, changes in height that could be accounted for by intervertebral disc changes; it uses metal bars (“fixing bars”) to stabilize certain anatomic points and safety glasses with a built-in leveling system.
The HVLA treatment is called a “pull-move” and was done with the participant in the side-lying position. In the research paper, a photograph was provided showing the position, and references directed readers to past studies using the technique. The HVLA treatments were delivered by one “therapist” (also referred to as a “care provider”), but the researchers did not specify the therapist’s training or background. The treatments were delivered in a double-blind fashion, but the exact meaning of this in the context of a hands-on therapy was not discussed.
The treatment and placebo groups were similar at baseline with respect to age, weight, height, low back pain as per a visual analog scale, stadiometry, and spinal flexion. At baseline, the treatment group had less degrees of range of motion on straight leg testing than the control group (39.10 vs 48.05, respectively, P = 0.004).
Pre- and post-intervention, there were no differences in the study variables in the control group. In contrast, all of the post-treatment measurements in the treatment group were statistically different when compared with pre-treatment (P < 0.001) (see Table 2). When the control group was compared to the treatment group, all study variable differences were statistically significant (P < 0.001). Essentially, these results showed that one HVLA treatment improved low back pain (lower score on the visual analog scale), increased hip range of motion (more degrees on straight leg raise testing), improved back flexibility (fingers closer to the floor on forward bend), and widened intervertebral disc space as per stadiometery. There were no dropouts in this trial. Adverse effects were not discussed.
This trial appears to be a vindication of spinal manipulation for the short-term relief of low back pain due to a degenerative disc disease etiology, corroborating some reviews.1 And, for many people who have otherwise maxed out pharmaceutical therapy, physical therapy, and corticosteroid injections, these results seem to be, well, a welcome relief. However, in many respects, these findings are nothing new; clinicians and patients alike can attest to the fact that spinal manipulation leads to initial benefits, which, in this physician’s professional experience, often wane with time. More compelling would have been a longitudinal study to examine the duration of benefit or a series of arms to elucidate how it would be possible to make the initial benefits last longer; for example, perhaps spinal manipulation paired with physical therapy is the key to provide instant relief, followed by musculoskeletal stability that maintains the positive changes measured in this clinical trial.
The researchers do bring some important nuances to the low back pain table. For example, their study variables hint at a mechanism of action. The measurements seem to indicate that HVLA opens the intervertebral disc space at the target joint and improves the straight leg raise testing, possibly an indication of, in their words, “neurodynamics of lower extremity posterior muscles and neural structures.” They extrapolate this finding to possible inhibitory effects on motor neurons and improved mechanosensitivity, both of which would have to be corroborated with more extensive neurological testing. As the researchers hypothesize, even the enhanced flexibility may indicate a mellowing of the somatosensory system, calming paravertebral muscle spasms. It is fascinating to think about how joint mobility may connect with neuromuscular feedback and, ultimately, patient experience.
The methodology proposed here is not airtight. In particular, it begs the question about the correct way to establish a control group. Surely the patients in the control group knew they were receiving a sham treatment by simply laying on the table for a few seconds, casting into doubt the double-blind nature of this study. Many researchers are grappling with how to create a true placebo or control group to which an integrative intervention can be compared. This is especially challenging when the intervention is individualized, such as a unique homeopathic remedy or traditional Chinese medicine prescription. Perhaps a failsafe control group isn’t absolutely necessary in all cases, but in this study patient perceptions may have played a significant role in the results seen and should have been better addressed.
Is spinal manipulation safe? We can’t tell from this study, as it wasn’t mentioned, but some reviews bring up that fact that the risks are non-negligible.2,3 And in this case, the researchers cherry-picked a cohort of patients for whom there was likely very little risk involved (no disc herniations, no prior surgeries, etc.). How many of our patients with low back pain go through such an onerous screening process prior to receiving spinal manipulation, especially when they self-refer for such treatments? Very few to be sure. That said, when appropriately administered by trained professionals, spinal manipulation may be a reasonably safe choice for the “right” patient, but most experts in the literature are calling for more data to accurately depict the risk-benefit profile of spinal manipulation.
- Rubinstein SM, et al. Spinal manipulative therapy for acute low-back pain. Cochrane Database Syst Rev 2012 Sep 12;9:CD008880.
- Gouveia LO, et al. Safety of chiropractic interventions: A systematic review. Spine (Phila Pa 1976) 2009;34:E405-413.
- Ernst E. Adverse effects of spinal manipulation: A systematic review. J R Soc Med 2007;100:330-338.