Short Report
Useful: Spinal Manipulation for Low Back Pain
By David Kiefer, MD
Bialosky JE, et al. Spinal manipulative therapy-specific changes in pain sensitivity in individuals with low back pain (NCT01168999). J Pain 2014;15:136-148.
- Spinal manipulative therapy provides benefits in one aspect of pain sensitivity for people
suffering from low back pain.
This placebo-controlled trial of 110 people with low back pain of any duration was designed to elicit the contribution of the placebo effect to benefits ascribed to spinal manipulative therapy (SMT). In the case of this study, SMT was administered by physical therapists and consisted of a high-velocity, low-amplitude force applied to the pelvis to rotate the lower spine. In addition to a "no intervention" group, two placebo groups were established: 1) a placebo SMT intended to mimic true SMT but with different biomechanics, and 2) an enhanced placebo SMT, wherein they were told The manual therapy technique you will receive has been shown to significantly reduce low back pain in some people.’’ These groups all received their intervention six times over a 2-week period, with clinical outcomes (psychological questionnaires, mechanical pain sensitivity, thermal pain sensitivity, suprathreshold heat response, and aftersensation) assessed at baseline and after the 2-week interventional period. In line with prior research, only the true SMT group showed a lessening of the suprathreshold heat response (P ≤ 0.05), a rating of response to heat applied to the plantar aspect of the dominant foot, which was used in previous trials and thought to have particular relevance to clinical pain. Overall pain intensity and disability improved in all groups similarly over the 2-week time period. Elaborate statistical techniques utilizing chi-squared analyses and t-test between the numerous variables were used to compare the different groups, outcome measurements, and time points, in order to find differences/similarities. The authors conclude that the benefits of SMT are likely due to SMT itself, rather than expectations from SMT, and seem mostly to benefit the suprathreshold heat response rather than other measurements of pain sensitivity. Extrapolating from animal studies, the authors make a case for how SMT likely affects the dorsal horn of the spinal cord. Overall, these results seem to corroborate an effect of SMT that extends beyond simply a placebo response due to expectation and provider touch, as well as the need to attempt to further delineate populations (i.e., acute vs chronic low back pain) most amenable to this therapeutic approach. The bottom line? There is a tangible and physiologically plausible benefit for SMT for people with low back pain; it should be on clinicians’ radar for this population.
