Author Names

Jun, P., Pagé , I., Vette, A., and Kawchuk, G.

Reviewer Name

Erica Block, SPT

Reviewer Affiliation(s)

Duke University School of Medicine, Doctor of Physical Therapy Division

 

Paper Abstract

Introduction In individuals having low back pain, the application of spinal manipulative therapy (SMT) has been shown to reduce spinal stiffness in those who report improvements in post-SMT disability. The underlying mechanism for this rapid change in stiffness is not understood presently. As clinicians and patients may benefit from a better understanding of this mechanism in terms of optimizing care delivery, the objective of this scoping review of current literature was to identify if potential mechanisms that explain this clinical response have been previously described or could be elucidated from existing data.  Methods Three literature databases were systematically searched (MEDLINE, CINAHL, and PubMed). Our search terms included subject headings and keywords relevant to SMT, spinal stiffness, lumbar spine, and mechanism. Inclusion criteria for candidate studies were publication in English, quantification of lumbar spinal stiffness before and after SMT, and publication between January 2000 and June 2019.  Results The search identified 1931 articles. Of these studies, 10 were included following the application of the inclusion criteria. From these articles, 7 themes were identified with respect to potential mechanisms described or derived from data: 1) change in muscle activity; 2) increase in mobility; 3) decrease in pain; 4) increase in pressure pain threshold; 5) change in spinal tissue behavior; 6) change in the central nervous system or reflex pathways; and 7) correction of a vertebral dysfunction.  Conclusions This scoping review identified 7 themes put forward by authors to explain changes in spinal stiffness following SMT. Unfortunately, none of the studies provided data which would support the promotion of one theme over another. As a result, this review suggests a need to develop a theoretical framework to explain rapid biomechanical changes following SMT to guide and prioritize future investigations in this important clinical area.

 

NIH Risk of Bias Tool

Quality Assessment of Systematic Reviews and Meta-Analyses

  1. Is the review based on a focused question that is adequately formulated and described?
  • Yes
  1. Were eligibility criteria for included and excluded studies predefined and specified?
  • Yes
  1. Did the literature search strategy use a comprehensive, systematic approach?
  • No

4. Were titles, abstracts, and full-text articles dually and independently reviewed for inclusion and exclusion to minimize bias?

  • Yes
  1. Was the quality of each included study rated independently by two or more reviewers using a standard method to appraise its internal validity?
  • Cannot Determine, Not Reported, Not Applicable
  1. Were the included studies listed along with important characteristics and results of each study?
  • Yes
  1. Was publication bias assessed?
  • Cannot Determine, Not Reported, Not Applicable
  1. Was heterogeneity assessed? (This question applies only to meta-analyses.)
  • Cannot Determine, Not Reported, Not Applicable

 

Key Finding #1

There are many potential mechanisms that could cause SMT to reduce spinal stiffness, however there is more research needed to further understand those mechanisms.

Key Finding #2

There is not one mechanism that has more evidence for being the cause of reduced stiffness post-SMT over another.

 

Please provide your summary of the paper

This scoping review investigated the potential mechanisms of how spinal manipulative therapy (SMT) reduces spinal stiffness. The different treatments analyzed in these studies included spinal manipulation, PA glides, lumbopelvic spinal manipulation, and manipulations using devices with external frames. From the 1,931 articles that this review explored, they discovered seven themes that could be potential mechanisms: change in muscle activity, increase in mobility, decrease in pain, increase in pressure pain threshold, change in spinal tissue behavior, change in the central nervous system, and lastly, correction of a vertebral dysfunction. With all the articles and studies that were reviewed, there weren’t any themes that could be prioritized as more likely to be a mechanism over others. The overall conclusion of this review is that there is a need for more research to truly understand the mechanism behind the changes in low back stiffness after spinal manipulation. A limitation of the review is that there were a variety of interventions examined which could have an effect on patient outcomes and understanding of the potential mechanisms. There was also a lack of inter-practitioner reliability.

Please provide your clinical interpretation of this paper.  Include how this study may impact clinical practice and how the results can be implemented.

The information from this scoping review is important for physical therapists to understand because as patients with low back pain are evaluated and treated, they will each have different structures in need of improvement. Understanding the mechanisms of SMT will help physical therapists determine which patients are most appropriate for this type of treatment and which may not experience the most benefit from it. Continuing this research will assist physical therapists in being able to provide individualized and higher quality care to each of their patients.