Publications by authors named "Gregory N Kawchuk"

51 Publications

Posterior to anterior spinal stiffness measured in a sample of 127 secondary care low back pain patients.

Clin Biomech (Bristol, Avon) 2021 Jul 10;87:105408. Epub 2021 Jun 10.

Department of Regional Health Research, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark; Spine Center of Southern Denmark, University Hospital of Southern Denmark, Østre Hougvej 55, 5500 Middelfart, Denmark.

Background: The sensation of spinal stiffness is a commonly reported symptom among back pain patients, with the clinical assessment of spinal stiffness usually being part of the decision-making process when deciding on providing manual treatment of low back pain. While any relationship between spinal stiffness and low back pain is likely to be multifactorial, prior exploration of this relationship has been overly simplistic (e.g., univariate regression analyses). The purpose of this study was to address this gap by taking a broader approach to compare instrumented measures of spinal stiffness to demographic characteristics, pain phenotypes, psychometrics, and spine-related disability in a sample of secondary care low back pain patients using multivariate regression analysis.

Methods: Instrumented spinal stiffness measures from 127 patients in secondary care were used to calculate terminal and global spinal stiffness scores. A best subset analysis was used to find the subsets of 14 independent variables that most accurately predicted stiffness based on the evaluation of the adjusted R-square, Akaike Information Criteria, and the Bayesian Information Criteria.

Findings: In the resulting multivariate models, sex (p < 0.001) and age (p < 0.001) were the primary determinants of terminal stiffness, while global stiffness was primarily determined by age (p = 0.003) and disability (p = 0.024).

Interpretation: Instrumented measures of spinal stiffness are multifactorial in nature, and future research into this area should make use of multivariate analyses.
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http://dx.doi.org/10.1016/j.clinbiomech.2021.105408DOI Listing
July 2021

Repetitive in vivo manual loading of the spine elicits cellular responses in porcine annuli fibrosi.

PLoS One 2021 23;16(3):e0248104. Epub 2021 Mar 23.

Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada.

Back pain and intervertebral disc degeneration are prevalent, costly, and widely treated by manual therapies, yet the underlying causes of these diseases are indeterminate as are the scientific bases for such treatments. The present studies characterize the effects of repetitive in vivo manual loads on porcine intervertebral disc cell metabolism using RNA deep sequencing. A single session of repetitive manual loading applied to the lumbar spine induced both up- and down-regulation of a variety of genes transcribed by cells in the ventral annuli fibrosi. The effect of manual therapy at the level of loading was greater than at a level distant to the applied load. Gene ontology and molecular pathway analyses categorized biological, molecular, and cellular functions influenced by repetitive manual loading, with over-representation of membrane, transmembrane, and pericellular activities. Weighted Gene Co-expression Network Analysis discerned enrichment in genes in pathways of inflammation and skeletogenesis. The present studies support previous findings of intervertebral disc cell mechanotransduction, and are the first to report comprehensively on the repertoire of gene targets influenced by mechanical loads associated with manual therapy interventions. The present study defines the cellular response of repeated, low-amplitude loads on normal healthy annuli fibrosi and lays the foundation for future work defining how healthy and diseased intervertebral discs respond to single or low-frequency manual loads typical of those applied clinically.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248104PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987143PMC
March 2021

The global summit on the efficacy and effectiveness of spinal manipulative therapy for the prevention and treatment of non-musculoskeletal disorders: a systematic review of the literature.

Chiropr Man Therap 2021 02 17;29(1). Epub 2021 Feb 17.

RMIT University, Melbourne, Australia.

Background: A small proportion of chiropractors, osteopaths, and other manual medicine providers use spinal manipulative therapy (SMT) to manage non-musculoskeletal disorders. However, the efficacy and effectiveness of these interventions to prevent or treat non-musculoskeletal disorders remain controversial.

Objectives: We convened a Global Summit of international scientists to conduct a systematic review of the literature to determine the efficacy and effectiveness of SMT for the primary, secondary and tertiary prevention of non-musculoskeletal disorders.

Global Summit: The Global Summit took place on September 14-15, 2019 in Toronto, Canada. It was attended by 50 researchers from 8 countries and 28 observers from 18 chiropractic organizations. At the summit, participants critically appraised the literature and synthesized the evidence.

Systematic Review Of The Literature: We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, the Cumulative Index to Nursing and Allied Health, and the Index to Chiropractic Literature from inception to May 15, 2019 using subject headings specific to each database and free text words relevant to manipulation/manual therapy, effectiveness, prevention, treatment, and non-musculoskeletal disorders. Eligible for review were randomized controlled trials published in English. The methodological quality of eligible studies was assessed independently by reviewers using the Scottish Intercollegiate Guidelines Network (SIGN) criteria for randomized controlled trials. We synthesized the evidence from articles with high or acceptable methodological quality according to the Synthesis without Meta-Analysis (SWiM) Guideline. The final risk of bias and evidence tables were reviewed by researchers who attended the Global Summit and 75% (38/50) had to approve the content to reach consensus.

Results: We retrieved 4997 citations, removed 1123 duplicates and screened 3874 citations. Of those, the eligibility of 32 articles was evaluated at the Global Summit and 16 articles were included in our systematic review. Our synthesis included six randomized controlled trials with acceptable or high methodological quality (reported in seven articles). These trials investigated the efficacy or effectiveness of SMT for the management of infantile colic, childhood asthma, hypertension, primary dysmenorrhea, and migraine. None of the trials evaluated the effectiveness of SMT in preventing the occurrence of non-musculoskeletal disorders. Consensus was reached on the content of all risk of bias and evidence tables. All randomized controlled trials with high or acceptable quality found that SMT was not superior to sham interventions for the treatment of these non-musculoskeletal disorders. Six of 50 participants (12%) in the Global Summit did not approve the final report.

Conclusion: Our systematic review included six randomized clinical trials (534 participants) of acceptable or high quality investigating the efficacy or effectiveness of SMT for the treatment of non-musculoskeletal disorders. We found no evidence of an effect of SMT for the management of non-musculoskeletal disorders including infantile colic, childhood asthma, hypertension, primary dysmenorrhea, and migraine. This finding challenges the validity of the theory that treating spinal dysfunctions with SMT has a physiological effect on organs and their function. Governments, payers, regulators, educators, and clinicians should consider this evidence when developing policies about the use and reimbursement of SMT for non-musculoskeletal disorders.
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http://dx.doi.org/10.1186/s12998-021-00362-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7890602PMC
February 2021

Self-reports vs. physical measures of spinal stiffness.

PeerJ 2020 7;8:e9598. Epub 2020 Dec 7.

Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.

Background: Objectively measured reduction in lumbar posterior-to-anterior (PA) stiffness is associated with pain relief in some, but not all persons with low back pain. Unfortunately, these measurements can be time consuming to perform. In comparison, the Lumbar Spine Instability Questionnaire (LSIQ) is intended to measure spinal instability and the Lumbar Spine Disability Index (LSDI) is created for self-reporting functional disability due to increased spinal stiffness. Given the above, the aim of this study is to compare measures of the LSIQ and LSDI with objective measures of lumbar PA stiffness as measured by a mechanical device, Vertetrack (VT), in patients with persistent non-specific low back pain (nsLBP).

Methods: Twenty-nine patients with nsLBP completed the LSIQ and LSDI at baseline and after two weeks. On these same occasions, PA spinal stiffness was measured using the VT. Between measurements, patients received four sessions of spinal manipulation. The resulting data was analyzed to determine the correlation between the self-report and objective measures of stiffness at both time points. Further, the patients were categorized into responders and non-responders based on pre-established cut points depending on values from the VT and compared those to self-report measures in order to determine whether the LSIQ and the LSDI were sensitive to change.

Results: Twenty-nine participants completed the study. Measures from the LSIQ and LSDI correlated poorly with objectively measured lumbar PA stiffness at baseline and also with the change scores. The change in objectively measured lumbar PA stiffness following spinal manipulation did not differ between those who improved, and those who did not improve according to the pre-specified cut-points. Finally, a reduction in lumbar PA stiffness following intervention was not associated with improvement in LSIQ and LSDI outcomes.

Conclusions: The current data indicate that the LSIQ and LSDI questionnaires do not correlate with measures obtained objectively by VT. Our results suggest that these objective and self- reported measures represent different domains and as such, cannot stand in place of one another.
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http://dx.doi.org/10.7717/peerj.9598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7727369PMC
December 2020

The bench-top accuracy of the VerteTrack spinal stiffness assessment device.

Chiropr Man Therap 2020 08 18;28(1):42. Epub 2020 Aug 18.

Department of Chiropractic, Faculty of Science and Engineering, Macquarie University, Sydney, Australia.

Background: The assessment of spinal stiffness by manual palpation in clinical settings has demonstrated both poor accuracy and reliability. More recently, mechanical methods for assessment of spinal stiffness have demonstrated superior accuracy and reliability. However, mechanical methods of spinal stiffness assessment can be expensive, time consuming and/or unsuited to clinical practice. While a new device has been designed to address these issues (VerteTrack), its benchtop performance remains unknown.

Aim: To measure the bench-top performance of VerteTrack.

Methods: A series of laboratory-based experiments were conducted in February 2018 to investigate the accuracy (precision and bias) of load and displacement measurements obtained by VerteTrack and then were compared against an appropriate reference standard. Measurements of both multiple-level continuous assessment (multiple spinal levels measured), and single-level assessment (single spinal level measured) were performed on a viscoelastic foam medium (AIREX® balance beam, Switzerland) and the resulting stiffness calculated.

Results: VerteTrack demonstrated high precision at all loads and displacements. There was minimal systematic measurement bias identified for applied versus reference load (mean bias = - 0.123 N; 95%CI - 0.182 to 0.428 N, p < .001), and no systematic measurement bias for measured versus reference displacement (mean difference = 0.02 mm; 95%CI - 0.09 to 0.14 mm, p < .001). The magnitude of stiffness obtained during multiple-level continuous assessment was on average 0.25 N/mm (2.79%) less than that for single-level assessment (95%CI - 0.67 to 0.17 N/mm, p < .001).

Conclusions: VerteTrack demonstrated high accuracy (high precision, low bias) under bench-top conditions. The difference in stiffness found between multiple versus single spinal levels should be considered in the research context, but is unlikely to be clinically relevant. The results of this study demonstrate that VerteTrack may be suitable for both single and multi-level spinal stiffness measurements in-vivo.
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http://dx.doi.org/10.1186/s12998-020-00331-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7433107PMC
August 2020

Clinicians' Ability to Detect a Palpable Difference in Spinal Stiffness Compared With a Mechanical Device.

J Manipulative Physiol Ther 2019 02 15;42(2):89-95. Epub 2019 Apr 15.

Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, Hong Kong.

Objective: The purpose of this study was to quantify the threshold at which clinicians can detect a difference in spinal stiffness of the thoracic and lumbar spine via palpation and then determine if this detection threshold would affect a clinician's ability to identify changes in spinal stiffness as measured by an objective instrument.

Methods: In this study, the threshold at which a change in spinal stiffness was detected was quantified in 12 experienced clinicians (physical therapists and doctors of chiropractic) by changing the differential stiffness in 2 inflatable targets until the clinician could no longer identify which was stiffer. In the second part of the study, clinicians then were asked to palpate pre-identified pairs of vertebrae in an asymptomatic volunteer and to identify the stiffer of the pair (T7 and L3, T7 and L4, L3 and L4), and the biomechanical stiffness of each vertebral pair was quantified objectively by a validated instrument.

Results: The mean stiffness detection threshold for the clinicians was 8%. Objective measurement of the stiffness differential between vertebral pairs was 30% for T7* and L3, 20% for T7* and L4, and 10% for L3* and L4 (*denotes the stiffer of the pair). Ten of 12 clinicians correctly identified T7 as stiffer when compared with L3 and T7 as stiffer than L4. Alternatively, when the differential vertebral pair stiffness was similar to the stiffness detection threshold (~8%), clinicians were less successful in identifying the stiffer vertebra of the pair; 4 of 12 clinicians correctly identified L3 as being stiffer compared with L4.

Conclusion: These results suggest that the physiological limits of human palpation may limit the ability of clinicians to identify small alterations in spine stiffness.
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http://dx.doi.org/10.1016/j.jmpt.2019.02.002DOI Listing
February 2019

X-ray vision: the accuracy and repeatability of a technology that allows clinicians to see spinal X-rays superimposed on a person's back.

PeerJ 2019 13;7:e6333. Epub 2019 Feb 13.

Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.

Objective: Since the discovery of ionizing radiation, clinicians have evaluated X-ray images separately from the patient. The objective of this study was to investigate the accuracy and repeatability of a new technology which seeks to resolve this historic limitation by projecting anatomically correct X-ray images on to a person's skin.

Methods: A total of 13 participants enrolled in the study, each having a pre-existing anteroposterior lumbar X-ray. Each participant's image was uploaded into the Hololens Mixed reality system which when worn, allowed a single examiner to view a participant's own X-ray superimposed on the participant's back. The projected image was topographically corrected using depth information obtained by the Hololens system then aligned via existing anatomic landmarks. Using this superimposed image, vertebral levels were identified and validated against spinous process locations obtained by ultrasound. This process was repeated 1-5 days later. The projection of each vertebra was deemed to be "on-target" if it fell within the known morphological dimensions of the spinous process for that specific vertebral level.

Results: The projection system created on-target projections with respect to individual vertebral levels 73% of the time with no significant difference seen between testing sessions. The average repeatability for all vertebral levels between testing sessions was 77%.

Conclusion: These accuracy and repeatability data suggest that the accuracy and repeatability of projecting X-rays directly on to the skin is feasible for identifying underlying anatomy and as such, has potential to place radiological evaluation within the patient context. Future opportunities to improve this procedure will focus on mitigating potential sources of error.
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http://dx.doi.org/10.7717/peerj.6333DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6377589PMC
February 2019

SafetyNET Community-based patient safety initiatives: development and application of a Patient Safety and Quality Improvement Survey.

J Can Chiropr Assoc 2018 Dec;62(3):130-142

Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta.

Objectives: To: 1) develop/adapt and validate an instrument to measure patient safety attitudes and opinions of community-based spinal manipulative therapy (SMT) providers; 2) implement the instrument; and 3) compare results among healthcare professions.

Methods: A review of the literature and content validation were used for the survey development. Community-based chiropractors and physiotherapists in 4 Canadian provinces were invited.

Results: The Agency for Healthcare Research and Quality's (AHRQ) Medical Office Survey on Patient Safety Culture was the preferred instrument. The survey was modified and validated, measuring 14 patient safety dimensions. 276 SMT providers volunteered to respond to the survey. Generally, SMT providers had similar or better patient safety dimension scores compared to the AHRQ 2016 medical offices database.

Discussion: We developed the first instrument measuring patient safety attitudes and opinions of community-based SMT providers. This instrument provides understanding of SMT providers' opinions and attitudes on patient safety and identifies potential areas for improvement.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6319430PMC
December 2018

Differential patient responses to spinal manipulative therapy and their relation to spinal degeneration and post-treatment changes in disc diffusion.

Eur Spine J 2019 02 2;28(2):259-269. Epub 2019 Jan 2.

Department of Physical Therapy, University of Alberta, Edmonton, AB, Canada.

Purpose: Our prior study revealed that people with non-specific low back pain (LBP) who self-reported a > 30% improvement in disability after SMT demonstrated significant post-treatment improvements in spinal stiffness, dynamic muscle thickness and disc diffusion, while those not having self-reported improvement did not have these objective changes. The mechanism underlying this differential post-SMT response remains unknown. This exploratory secondary analysis aimed to determine whether persons with non-specific LBP who respond to spinal SMT have unique lumbar magnetic resonance imaging (MRI) findings compared to SMT non-responders.

Methods: Thirty-two participants with non-specific LBP received lumbar MRI before and after SMT on Day 1. Resulting images were assessed for facet degeneration, disc degeneration, Modic changes and apparent diffusion coefficient (ADC). SMT was provided again on Day 4 without imaging. SMT responders were classified as having a ≥ 30% reduction in their modified Oswestry disability index at Day 7. Baseline MRI findings between responders and non-responders were compared. The associations between SMT responder status and the presence/absence of post-SMT increases in ADC values of discs associated with painful/non-painful segments as determined by palpation were calculated. In this secondary analysis, a statistical trend was considered as a P value between 0.05 and 0.10.

Results: Although there was no significant between-group difference in all spinal degenerative features (e.g. Modic changes), SMT responders tended to have a lower prevalence of severely degenerated facets (P = 0.05) and higher baseline ADC values at the L4-5 disc when compared to SMT non-responders (P = 0.09). Post hoc analyses revealed that 180 patients per group should have been recruited to find significant between-group differences in the two features. SMT responders were also characterized by significant increases in post-SMT ADC values at discs associated with painful segments identified by palpation (P < 0.01).

Conclusions: The current secondary analysis suggests that the spines of SMT responders appear to differ from non-responders with respect to degeneration changes in posterior joints and disc diffusion. Although this analysis was preliminary, it provides a new direction to investigate the mechanisms underlying SMT and the existence of discrete forms of treatment-specific LBP. These slides can be retrieved under Electronic Supplementary Material.
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http://dx.doi.org/10.1007/s00586-018-5851-2DOI Listing
February 2019

Does the application site of spinal manipulative therapy alter spinal tissues loading?

Spine J 2018 06 31;18(6):1041-1052. Epub 2018 Jan 31.

Department of Physical Therapy, University of Alberta, 8205 114 Street, University of Alberta, Edmonton, Alberta, T6G 2G4, Canada.

Background Context: Previous studies found that the intervertebral disc (IVD) experiences the greatest loads during spinal manipulation therapy (SMT).

Purpose: Based on that, this study aimed to determine if loads experienced by spinal tissues are significantly altered when the application site of SMT is changed.

Study Design: A biomechanical robotic serial dissection study.

Sample: Thirteen porcine cadaveric motion segments.

Outcome Measures: Forces experienced by lumbar spinal tissues.

Methods: A servo-controlled linear actuator provided standardized 300 N SMT simulations to six different cutaneous locations of the porcine lumbar spine: L2-L3 and L3-L4 facet joints (FJ), L3 and L4 transverse processes (TVP), and the space between the FJs and the TVPs (BTW). Vertebral kinematics were tracked optically using indwelling bone pins; the motion segment was removed and mounted in a parallel robot equipped with a six-axis load cell. Movements of each SMT application at each site were replayed by the robot with the intact specimen and following the sequential removal of spinal ligaments, FJs and IVD. Forces induced by SMT were recorded, and specific axes were analyzed using linear mixed models.

Results: Analyses yielded a significant difference (p<.05) in spinal structures loads as a function of the application site. Spinal manipulative therapy application at the L3 vertebra caused vertebral movements and forces between L3 and L4 spinal segment in the opposite direction to when SMT was applied at L4 vertebra. Additionally, SMT applications over the soft tissue between adjacent vertebrae significantly decreased spinal structure loads.

Conclusion: Applying SMT with a constant force at different spinal levels creates different relative kinetics of the spinal segments and load spinal tissues in significantly different magnitudes.
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http://dx.doi.org/10.1016/j.spinee.2018.01.008DOI Listing
June 2018

Feeling stiffness in the back: a protective perceptual inference in chronic back pain.

Sci Rep 2017 08 29;7(1):9681. Epub 2017 Aug 29.

Department of Physical Therapy, Faculty of Rehabilitation Medicine, The University of Alberta, Edmonton, Alberta, Canada.

Does feeling back stiffness actually reflect having a stiff back? This research interrogates the long-held question of what informs our subjective experiences of bodily state. We propose a new hypothesis: feelings of back stiffness are a protective perceptual construct, rather than reflecting biomechanical properties of the back. This has far-reaching implications for treatment of pain/stiffness but also for our understanding of bodily feelings. Over three experiments, we challenge the prevailing view by showing that feeling stiff does not relate to objective spinal measures of stiffness and objective back stiffness does not differ between those who report feeling stiff and those who do not. Rather, those who report feeling stiff exhibit self-protective responses: they significantly overestimate force applied to their spine, yet are better at detecting changes in this force than those who do not report feeling stiff. This perceptual error can be manipulated: providing auditory input in synchrony to forces applied to the spine modulates prediction accuracy in both groups, without altering actual stiffness, demonstrating that feeling stiff is a multisensory perceptual inference consistent with protection. Together, this presents a compelling argument against the prevailing view that feeling stiff is an isomorphic marker of the biomechanical characteristics of the back.
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http://dx.doi.org/10.1038/s41598-017-09429-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5575135PMC
August 2017

Association of lumbar spine stiffness and flexion-relaxation phenomenon with patient-reported outcomes in adults with chronic low back pain - a single-arm clinical trial investigating the effects of thrust spinal manipulation.

BMC Complement Altern Med 2017 Jun 9;17(1):303. Epub 2017 Jun 9.

Palmer Center for Chiropractic Research, Palmer College of Chiropractic, 741 Brady Street, Davenport, IA, 52803, USA.

Background: Spinal manipulation (SM) is used commonly for treating low back pain (LBP). Spinal stiffness is routinely assessed by clinicians performing SM. Flexion-relaxation ratio (FRR) was shown to distinguish between LBP and healthy populations. The primary objective of this study was to examine the association of these two physiological variables with patient-reported pain intensity and disability in adults with chronic LBP (>12 weeks) receiving SM.

Methods: A single-arm trial provided 12 sessions of side-lying thrust SM in the lumbosacral region over 6 weeks. Inclusion criteria included 21-65 years old, Roland-Morris Disability Questionnaire (RMDQ) score ≥ 6 and numerical pain rating score ≥ 2. Spinal stiffness and FRR were assessed pre-treatment at baseline, after 2 weeks and after 6 weeks of treatment. Lumbar spine global stiffness (GS) were calculated from the force-displacement curves obtained using i) hand palpation, ii) a hand-held device, and iii) an automated indenter device. Lumbar FRR was assessed during trunk flexion-extension using surface electromyography. The primary outcomes were RMDQ and pain intensity measured by visual analog scale (VAS). Mixed-effects regression models were used to analyze the data.

Results: The mean age of the 82 participants was 45 years; 48% were female; and 84% reported LBP >1 year. The mean (standard deviation) baseline pain intensity and RMDQ were 46.1 (18.1) and 9.5 (4.3), respectively. The mean reduction (95% confidence interval) after 6 weeks in pain intensity and RMDQ were 20.1 mm (14.1 to 26.1) and 4.8 (3.7 to 5.8). There was a small change over time in the palpatory GS but not in the hand-held or automated GS, nor in FRR. The addition of each physiologic variable did not affect the model-estimated changes in VAS or RMDQ over time. There was no association seen between physiological variables and LBP intensity. Higher levels of hand-held GS at L3 and automated GS were significantly associated with higher levels of RMDQ (p = 0.02 and 0.03, respectively) and lower levels of flexion and extension FRR were significantly associated with higher levels of RMDQ (p = 0.02 and 0.008, respectively) across the 3 assessment time points.

Conclusions: Improvement in pain and disability observed in study participants with chronic LBP was not associated with the measured GS or FRR.

Trial Registration: NCT01670292 on clinicaltrials.gov, August 2, 2012.
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http://dx.doi.org/10.1186/s12906-017-1821-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5466774PMC
June 2017

Procedure Selection and Patient Positioning Influence Spine Kinematics During High-Velocity, Low-Amplitude Spinal Manipulation Applied to the Low Back.

J Manipulative Physiol Ther 2017 Mar - Apr;40(3):147-155. Epub 2017 Feb 10.

Department of Graduate Education and Research Programs, Canadian Memorial Chiropractic College, Toronto, ON, Canada. Electronic address:

Objectives: This investigation compared indirect 3-dimensional angular kinematics (position, velocity, and acceleration) of the lumbar spine for 2 different high-velocity, low-amplitude (HVLA) spinal manipulation procedures (lumbar spinous pull or push), and altered initial patient lower limb posture.

Methods: Twenty-four participants underwent 6 HVLA procedures directed toward the presumed L4 vertebra, reflecting each combination of 2 variants of a spinal manipulation application technique (spinous pull and push) and 3 initial hip flexion angles (0°, 45°, and 90°) applied using a right lateral recumbent patient position. All contact forces and moments between the patient and the external environment, as well as 3-dimensional kinematics of the patient's pelvis and thorax, were recorded. Lumbar spine angular positions, velocities, and accelerations were analyzed within the preload and impulse stages of each HVLA trial.

Results: Lumbar spine left axial rotation was greater for the pull HVLA. The pull HVLA also generated a greater maximum (leftward) and lower minimum (rightward) axial rotation velocity and deceleration and greater leftward and rightward lateral bend velocities, acceleration, and deceleration components. Not flexing the hip produced the greatest amount of extension, as well as the lowest axial rotation and maximum axial rotation acceleration during the impulse.

Conclusions: This investigation provides basic kinematic information for clinicians to understand the similarities and differences between 2 HVLA side-lying manipulations in the lumbar spine. Use of these findings and novel technology can drive future research initiatives that can both affect clinical decision making and influence teaching environments surrounding spinal manipulative therapy skill acquisition.
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http://dx.doi.org/10.1016/j.jmpt.2016.10.014DOI Listing
April 2018

Spinal Tissue Loading Created by Different Methods of Spinal Manipulative Therapy Application.

Spine (Phila Pa 1976) 2017 May;42(9):635-643

Department of Physical Therapy, University of Alberta, Edmonton, AB, Canada.

Study Design: Comparative study using robotic replication of spinal manipulative therapy (SMT) vertebral kinematics together with serial dissection.

Objective: The aim of this study was to quantify loads created in cadaveric spinal tissues arising from three different forms of SMT application.

Summary Of Background Data: There exist many distinct methods by which to apply SMT. It is not known presently whether different forms of SMT application have different effects on spinal tissues. Should the method of SMT application modulate spinal tissue loading, quantifying this relation may help explain the varied outcomes of SMT in terms of effect and safety.

Methods: SMT was applied to the third lumbar vertebra in 12 porcine cadavers using three SMT techniques: a clinical device that applies forces through a hand-held instrument (INST), a manual technique of applying SMT clinically (MAN) and a research device that applies parameters of manual SMT through a servo-controlled linear actuator motor (SERVO). The resulting kinematics from each SMT application were tracked optically via indwelling bone pins. The L3/L4 segment was then removed, mounted in a parallel robot and the resulting kinematics from SMT replayed for each SMT application technique. Serial dissection of spinal structures was conducted to quantify loading characteristics of discrete spinal tissues.

Results: In terms of load magnitude, SMT application with MAN and SERVO created greater forces than INST in all conditions (P < 0.05). Additionally, MAN and SERVO created comparable posterior forces in the intact specimen, but MAN created greater posterior forces on IVD structures compared to SERVO (P < 0.05).

Conclusion: Specific methods of SMT application create unique vertebral loading characteristics, which may help explain the varied outcomes of SMT in terms of effect and safety.

Level Of Evidence: N/A.
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http://dx.doi.org/10.1097/BRS.0000000000002096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5407629PMC
May 2017

The Clinical Value of Assessing Lumbar Posteroanterior Segmental Stiffness: A Narrative Review of Manual and Instrumented Methods.

PM R 2017 Aug 16;9(8):816-830. Epub 2016 Dec 16.

Department of Physical Therapy, University of Alberta, Edmonton, Canada(†).

Abnormal spinal segmental motion/stiffness is purported to be a cause, or an effect of, low back pain. Therefore, the assessment of posteroanterior segmental spinal stiffness is a common practice in clinical and research settings. In clinical settings, manipulative practitioners routinely assess spinal stiffness manually to guide clinical decision-making. Unfortunately, the reliability of manual segmental spinal stiffness assessment is poor. As a result, various spinal stiffness-testing devices have been developed to improve the reliability and accuracy of spinal stiffness measures. Although previous critical and systematic reviews have summarized the evidence regarding the reliability and confounding factors of manual and/or instrumented spinal stiffness measurements, no available review has summarized the principles of various spinal stiffness measurement methods nor pragmatic recommendations to optimize these measurements. Importantly, although posteroanterior segmental spinal stiffness is hypothesized to be related closely to low back pain or clinical outcomes after treatments, no review has been conducted to summarize evidence related to these premises and to discuss factors that can confound these relations. Against this background, this narrative review revisits the concept of both manual and instrumented spinal stiffness assessments, summarizes the pragmatic recommendations for minimizing measurement errors, reviews the potential relations between segmental spinal stiffness and low back pain, and provides future clinical research directions that can benefit clinicians and researchers alike.

Level Of Evidence: Not applicable.
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http://dx.doi.org/10.1016/j.pmrj.2016.12.001DOI Listing
August 2017

Tissue loading created during spinal manipulation in comparison to loading created by passive spinal movements.

Sci Rep 2016 12 1;6:38107. Epub 2016 Dec 1.

Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada.

Spinal manipulative therapy (SMT) creates health benefits for some while for others, no benefit or even adverse events. Understanding these differential responses is important to optimize patient care and safety. Toward this, characterizing how loads created by SMT relate to those created by typical motions is fundamental. Using robotic testing, it is now possible to make these comparisons to determine if SMT generates unique loading scenarios. In 12 porcine cadavers, SMT and passive motions were applied to the L3/L4 segment and the resulting kinematics tracked. The L3/L4 segment was removed, mounted in a parallel robot and kinematics of SMT and passive movements replayed robotically. The resulting forces experienced by L3/L4 were collected. Overall, SMT created both significantly greater and smaller loads compared to passive motions, with SMT generating greater anterioposterior peak force (the direction of force application) compared to all passive motions. In some comparisons, SMT did not create significantly different loads in the intact specimen, but did so in specific spinal tissues. Despite methodological differences between studies, SMT forces and loading rates fell below published injury values. Future studies are warranted to understand if loading scenarios unique to SMT confer its differential therapeutic effects.
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http://dx.doi.org/10.1038/srep38107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131487PMC
December 2016

Patient-Induced Reaction Forces and Moments Are Influenced by Variations in Spinal Manipulative Technique.

Spine (Phila Pa 1976) 2017 Jan;42(2):E71-E77

Department of Graduate Education and Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.

Study Design: An in vivo biomechanical study.

Objective: The aim of the present study was to quantify and compare the reaction loads for two spinal manipulation therapy (SMT) procedures commonly used for low back pain using a biomechanical computer model.

Summary Of Background Data: Contemporary computer-driven rigid linked-segment models (LSMs) have made it feasible to analyze low back kinetics and kinematics during various activities including SMT procedures. Currently, a comprehensive biomechanical model analyzing actual differences in loading effects between different SMT procedures is lacking.

Methods: Twenty-four healthy/asymptomatic participants received a total of six SMT applications, representing all combinations of two similar SMT procedures within three patient hip flexion angles. All contact forces, patient torso kinematics, and inertial properties were entered into a dynamic three-dimensional LSM to calculate lumbar reaction forces and moments. Peak net applied force along with the maximums, minimums, and ranges for each component of the three-dimensional reaction force and moment vectors during each SMT procedure was analyzed.

Results: One specific SMT technique (lumbar spinous pull) produced greater maximum anterior-posterior reaction force and both lateral bending and axial twisting reaction moments compared to the other technique (lumbar push procedure [all P ≤ 0.034]). SMT trials without hip flexion had lower maximum medial-lateral reaction force and range compared to those with 45 and 90 degrees of hip flexion (all P ≤ 0.041). There were no interactions between procedure and hip angle for any of the dependent measurements.

Conclusion: The technique used to apply SMT and the participant's initial hip orientation induced significantly different actions on the low back. These findings and future research can improve patient outcomes and safety by informing clinicians on how to best use SMT given specific types of low back pain.

Level Of Evidence: 2.
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http://dx.doi.org/10.1097/BRS.0000000000001725DOI Listing
January 2017

Does experimental low back pain change posteroanterior lumbar spinal stiffness and trunk muscle activity? A randomized crossover study.

Clin Biomech (Bristol, Avon) 2016 05 31;34:45-52. Epub 2016 Mar 31.

Department of Physical Therapy, University of Alberta, Edmonton, Alberta, Canada.

Background: While some patients with low back pain demonstrate increased spinal stiffness that decreases as pain subsides, this observation is inconsistent. Currently, the relation between spinal stiffness and low back pain remains unclear. This study aimed to investigate the effects of experimental low back pain on temporal changes in posteroanterior spinal stiffness and concurrent trunk muscle activity.

Method: In separate sessions five days apart, nine asymptomatic participants received equal volume injections of hypertonic or isotonic saline in random order into the L3-L5 interspinous ligaments. Pain intensity, spinal stiffness (global and terminal stiffness) at the L3 level, and the surface electromyographic activity of six trunk muscles were measured before, immediately after, and 25-minute after injections. These outcome measures under different saline conditions were compared by generalized estimating equations.

Findings: Compared to isotonic saline injections, hypertonic saline injections evoked significantly higher pain intensity (mean difference: 5.7/10), higher global (mean difference: 0.73N/mm) and terminal stiffness (mean difference: 0.58N/mm), and increased activity of four trunk muscles during indentation (P<0.05). Both spinal stiffness and trunk muscle activity returned to baseline levels as pain subsided.

Interpretation: While previous clinical research reported inconsistent findings regarding the association between spinal stiffness and low back pain, our study revealed that experimental pain caused temporary increases in spinal stiffness and concurrent trunk muscle co-contraction during indentation, which helps explain the temporal relation between spinal stiffness and low back pain observed in some clinical studies. Our results substantiate the role of spinal stiffness assessments in monitoring back pain progression.
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http://dx.doi.org/10.1016/j.clinbiomech.2016.03.006DOI Listing
May 2016

Structural health monitoring (vibration) as a tool for identifying structural alterations of the lumbar spine: a twin control study.

Sci Rep 2016 Mar 11;6:22974. Epub 2016 Mar 11.

MOVE Research Institute Amsterdam, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.

Structural health monitoring (SHM) is an engineering technique used to identify mechanical abnormalities not readily apparent through other means. Recently, SHM has been adapted for use in biological systems, but its invasive nature limits its clinical application. As such, the purpose of this project was to determine if a non-invasive form of SHM could identify structural alterations in the spines of living human subjects. Lumbar spines of 10 twin pairs were visualized by magnetic resonance imaging then assessed by a blinded radiologist to determine whether twin pairs were structurally concordant or discordant. Vibration was then applied to each subject's spine and the resulting response recorded from sensors overlying lumbar spinous processes. The peak frequency, area under the curve and the root mean square were computed from the frequency response function of each sensor. Statistical analysis demonstrated that in twins whose structural appearance was discordant, peak frequency was significantly different between twin pairs while in concordant twins, no outcomes were significantly different. From these results, we conclude that structural changes within the spine can alter its vibration response. As such, further investigation of SHM to identify spinal abnormalities in larger human populations is warranted.
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http://dx.doi.org/10.1038/srep22974DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786826PMC
March 2016

Neural Responses to Physical Characteristics of a High-velocity, Low-amplitude Spinal Manipulation: Effect of Thrust Direction.

Spine (Phila Pa 1976) 2018 Jan;43(1):1-9

Palmer College of Chiropractic, Davenport, IA.

Study Design: Electrophysiological recordings were obtained from proprioceptors in deep lumbar paraspinal muscles of anesthetized cats during high-velocity low-amplitude spinal manipulation (HVLA-SM).

Objective: To determine how thrust direction of an HVLA-SM affects neural input from back musculature.

Summary Of Background Data: A clinician's ability to apply the thrust of an HVLA-SM in a specified direction is considered an important component of its optimal delivery. However, previous biomechanical studies indicate that the shear force component of the thrust vector is not actually transmitted to paraspinal tissues deep to the thoracolumbar fascia because the skin-fascia interface is frictionless.

Methods: Neural activity from muscle spindles in the multifidus and longissimus muscles was recorded from L6 dorsal rootlets in 18 anesthetized cats. After preload to the spinal tissues, HVLA-SMs (100-ms thrust duration) were applied through the intact skin overlying the L6 lamina. Thrusts were applied at angles oriented perpendicularly to the back and obliquely at 15° and 30° medialward or cranialward using a 6 × 6 Latin square design with three replicates. The normal force component was kept constant at 21.3 N. HVLA-SMs were preceded and followed by simulated spinal movement applied to the L6 vertebra. Changes in mean instantaneous discharge frequency (ΔMIF) of muscle spindles were determined both during the thrust and spinal movement.

Results: ΔMIFs during the HVLA-SM thrust were significantly greater in response to all thrust directions compared with the preload alone, but there was no difference in ΔMIF for any of the thrust directions during the HVLA-SM. HVLA-SM decreased some of the responses to simulated spinal movement but thrust direction had no effect on these changes.

Conclusion: The shear force component of an HVLA-SM's thrust vector is not transmitted to the underlying vertebra sufficient to activate muscle spindles of the attached muscles. Implications for clinical practice and clinical research are discussed.

Level Of Evidence: N/A.
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http://dx.doi.org/10.1097/BRS.0000000000001344DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4894003PMC
January 2018

Quantification of loading in biomechanical testing: the influence of dissection sequence.

J Biomech 2015 Sep 26;48(12):3522-6. Epub 2015 Jun 26.

Department of Physical Therapy, University of Alberta, Edmonton, AB, Canada. Electronic address:

Sequential dissection is a technique used to investigate loads experienced by articular tissues. When the joint of interest is tested in an unconstrained manner, its kinematics change with each tissue removal. To address this limitation, sufficiently rigid robots are used to constrain joint kinematics. While this approach can quantify loads experienced by each tissue, it does not assure similar results when removal order is changed. Specifically, structure loading is assumed to be independent of removal order if the structure behaves linearly (i.e. principle of superposition applies), but dependent on removal order when response is affected by material and/or geometry nonlinearities and/or viscoelasticiy (e.g. biological tissues). Therefore, this experiment was conducted to evaluate if structure loading created through robotic testing is dependent on the order in which connectors are removed. Six identical models were 3D printed. Each model was composed of 2 rigid bodies and 3 connecting structures with nonlinear time-dependent behavior. To these models, pure rotations were applied about a predefined static center of rotation using a parallel robot. A unique dissection sequence was used for each of the six models and the same movements applied robotically after each dissection. When comparing the moments experienced by each structure between different removal sequences, a statistically significant difference (p<0.05) was observed. These results suggest that even in an optimized environment, the sequence in which nonlinear viscoelastic structures are removed influence model loading. These findings support prior work suggesting that tissue loads obtained from robotic testing are specific to removal order.
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http://dx.doi.org/10.1016/j.jbiomech.2015.06.020DOI Listing
September 2015

Do participants with low back pain who respond to spinal manipulative therapy differ biomechanically from nonresponders, untreated controls or asymptomatic controls?

Spine (Phila Pa 1976) 2015 Sep;40(17):1329-37

*Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong †Department of Physical Therapy, University of Alberta, Alberta, Canada ‡Department of Radiology and Diagnostic Imaging, University of Alberta, Alberta, Canada §University of Alberta Hospital, Alberta, Canada; and ¶Department of Mathematical and Statistical Sciences, University of Alberta, Alberta, Canada.

Study Design: Nonrandomized controlled study.

Objective: To determine whether patients with low back pain (LBP) who respond to spinal manipulative therapy (SMT) differ biomechanically from nonresponders, untreated controls or asymptomatic controls.

Summary Of Background Data: Some but not all patients with LBP report improvement in function after SMT. When compared with nonresponders, studies suggest that SMT responders demonstrate significant changes in spinal stiffness, muscle contraction, and disc diffusion. Unfortunately, the significance of these observations remains uncertain given methodological differences between studies including a lack of controls.

Methods: Participants with LBP and asymptomatic controls attended 3 sessions for 7 days. On sessions 1 and 2, participants with LBP received SMT (+LBP/+SMT, n = 32) whereas asymptomatic controls did not (-LBP/-SMT, n = 57). In these sessions, spinal stiffness and multifidus thickness ratios were obtained before and after SMT and on day 7. Apparent diffusion coefficients from lumbar discs were obtained from +LBP/+SMT participants before and after SMT on session 1 and from an LBP control group that did not receive SMT (+LBP/-SMT, n = 16). +LBP/+SMT participants were dichotomized as responders/nonresponders on the basis of self-reported disability on day 7. A repeated measures analysis of covariance was used to compare apparent diffusion coefficients among responders, nonresponders, and +LBP/-SMT subjects, as well as spinal stiffness or multifidus thickness ratio among responders, nonresponders, and -LBP/-SMT subjects.

Results: After the first SMT, SMT responders displayed statistically significant decreases in spinal stiffness and increases in multifidus thickness ratio sustained for more than 7 days; these findings were not observed in other groups. Similarly, only SMT responders displayed significant post-SMT improvement in apparent diffusion coefficients.

Conclusion: Those reporting post-SMT improvement in disability demonstrated simultaneous changes between self-reported and objective measures of spinal function. This coherence did not exist for asymptomatic controls or no-treatment controls. These data imply that SMT impacts biomechanical characteristics within SMT responders not present in all patients with LBP. This work provides a foundation to investigate the heterogeneous nature of LBP, mechanisms underlying differential therapeutic response, and the biomechanical and imaging characteristics defining responders at baseline.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000000981DOI Listing
September 2015

Real-time visualization of joint cavitation.

PLoS One 2015 15;10(4):e0119470. Epub 2015 Apr 15.

Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.

Cracking sounds emitted from human synovial joints have been attributed historically to the sudden collapse of a cavitation bubble formed as articular surfaces are separated. Unfortunately, bubble collapse as the source of joint cracking is inconsistent with many physical phenomena that define the joint cracking phenomenon. Here we present direct evidence from real-time magnetic resonance imaging that the mechanism of joint cracking is related to cavity formation rather than bubble collapse. In this study, ten metacarpophalangeal joints were studied by inserting the finger of interest into a flexible tube tightened around a length of cable used to provide long-axis traction. Before and after traction, static 3D T1-weighted magnetic resonance images were acquired. During traction, rapid cine magnetic resonance images were obtained from the joint midline at a rate of 3.2 frames per second until the cracking event occurred. As traction forces increased, real-time cine magnetic resonance imaging demonstrated rapid cavity inception at the time of joint separation and sound production after which the resulting cavity remained visible. Our results offer direct experimental evidence that joint cracking is associated with cavity inception rather than collapse of a pre-existing bubble. These observations are consistent with tribonucleation, a known process where opposing surfaces resist separation until a critical point where they then separate rapidly creating sustained gas cavities. Observed previously in vitro, this is the first in-vivo macroscopic demonstration of tribonucleation and as such, provides a new theoretical framework to investigate health outcomes associated with joint cracking.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119470PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398549PMC
January 2016

Neural responses to the mechanical characteristics of high velocity, low amplitude spinal manipulation: Effect of specific contact site.

Man Ther 2015 Dec 27;20(6):797-804. Epub 2015 Mar 27.

Palmer Center for Chiropractic Research, Davenport, IA, USA. Electronic address:

Background: Systematic investigations are needed identifying how variability in the biomechanical characteristics of spinal manipulation affects physiological responses. Such knowledge may inform future clinical practice and research study design.

Objective: To determine how contact site for high velocity, low amplitude spinal manipulation (HVLA-SM) affects sensory input to the central nervous system.

Design: HVLA-SM was applied to 4 specific anatomic locations using a no-HVLA-SM control at each location randomized in an 8×8 Latin square design in an animal model.

Methods: Neural activity from muscle spindles in the multifidus and longissimus muscles were recorded from L6 dorsal rootlets in 16 anesthetized cats. A posterior to anterior HVLA-SM was applied through the intact skin overlying the L6 spinous process, lamina, inferior articular process and L7 spinous process. HVLA-SMs were preceded and followed by simulated spinal movement applied to the L6 vertebra. Change in mean instantaneous discharge frequency (ΔMIF) was determined during the thrust and the simulated spinal movement.

Results: All contact sites increased L6 muscle spindle discharge during the thrust. Contact at all L6 sites significantly increased spindle discharge more than at the L7 site when recording at L6. There were no differences between L6 contact sites. For simulated movement, the L6 contact sites but not the L7 contact site significantly decreased L6 spindle responses to a change in vertebral position but not to movement to that position.

Conclusions: This animal study showed that contact site for an HVLA-SM can have a significant effect on the magnitude of sensory input arising from muscle spindles in the back.
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http://dx.doi.org/10.1016/j.math.2015.03.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4584162PMC
December 2015

Study protocol for patient response to spinal manipulation - a prospective observational clinical trial on physiological and patient-centered outcomes in patients with chronic low back pain.

BMC Complement Altern Med 2014 Aug 8;14:292. Epub 2014 Aug 8.

Palmer Center for Chiropractic Research, Palmer College of Chiropractic, 741 Brady Street, Davenport, Lowa IA 52803, USA.

Background: Low back pain (LBP) is a major health issue due to its high prevalence rate and socioeconomic cost. While spinal manipulation (SM) is recommended for LBP treatment by recently published clinical guidelines, the underlying therapeutic mechanisms remain unclear. Spinal stiffness is routinely examined and used in clinical decisions for SM delivery. It has also been explored as a predictor for clinical improvement. Flexion-relaxation phenomenon has been demonstrated to distinguish between LBP and healthy populations. The primary objective of the current study is to collect preliminary estimates of variability and effect size for the associations of these two physiological measures with patient-centered outcomes in chronic LBP patients. Additionally biomechanical characteristics of SM delivery are collected with the intention to explore the potential dose-response relationship between SM and LBP improvement.

Methods/design: This is a prospective, observational study applying side-lying, high velocity, low amplitude SM as treatment for patients with LBP over a course of 6 weeks. Approximately 80 participants will be enrolled if they present with chronic LBP of 1, 2 or 3 in Quebec Task Force Classification for spinal disorders, a Roland-Morris Disability Questionnaire (RMDQ) score ≥ 6, and persistent LBP ≥ 2 with a maximum ≥ 4 using numerical rating scale. Patient-centered outcomes include LBP using visual analog scale, RMDQ, and PROMIS-29. Lumbar spine stiffness is assessed using palpation, a hand-held instrumented device, and an automated device. Flexion-relaxation is assessed using surface electromyography at the third level of the lumbar spine. Biomechanical characteristics of SM are assessed using a self-reported, itemized description system, as well as advanced kinetic measures that will be applied to estimate forces and moments at the lumbar segment level targeted by SM.

Discussion: Beside alterations in material properties of the passive components of the spine, increased neuromuscular activity may also contribute to a stiffened spine. Examining changes in both spinal stiffness and flexion-relaxation along the course of the treatment provides an opportunity to understand if the therapeutic effect of SM is associated with its action on active and/or passive components of the spine.

Trial Registration: NCT01670292 on clinicaltrials.gov.
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http://dx.doi.org/10.1186/1472-6882-14-292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4139615PMC
August 2014

Neural responses to the mechanical parameters of a high-velocity, low-amplitude spinal manipulation: effect of preload parameters.

J Manipulative Physiol Ther 2014 Feb 3;37(2):68-78. Epub 2014 Jan 3.

Professor Emeritus, Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, Iowa. Electronic address:

Objective: The purpose of this study was to determine how the preload that precedes a high-velocity, low-amplitude spinal manipulation (HVLA-SM) affects muscle spindle input from lumbar paraspinal muscles both during and after the HVLA-SM.

Methods: Primary afferent activity from muscle spindles in lumbar paraspinal muscles were recorded from the L6 dorsal root in anesthetized cats. High-velocity, low-amplitude spinal manipulation of the L6 vertebra was preceded either by no preload or systematic changes in the preload magnitude, duration, and the presence or absence of a downward incisural point. Immediate effects of preload on muscle spindle responses to the HVLA-SM were determined by comparing mean instantaneous discharge frequencies (MIF) during the HVLA-SM's thrust phase with baseline. Longer lasting effects of preload on spindle responses to the HVLA-SM were determined by comparing MIF during slow ramp and hold movement of the L6 vertebra before and after the HVLA-SM.

Results: The smaller compared with the larger preload magnitude and the longer compared with the shorter preload duration significantly increased (P = .02 and P = .04, respectively) muscle spindle responses during the HVLA-SM thrust. The absence of preload had the greatest effect on the change in MIF. Interactions between preload magnitude, duration, and downward incisural point often produced statistically significant but arguably physiologically modest changes in the passive signaling properties of the muscle spindle after the manipulation.

Conclusion: Because preload parameters in this animal model were shown to affect neural responses to an HVLA-SM, preload characteristics should be taken into consideration when judging this intervention's therapeutic benefit in both clinical efficacy studies and in clinical practice.
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http://dx.doi.org/10.1016/j.jmpt.2013.12.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946664PMC
February 2014

Do changes in transversus abdominis and lumbar multifidus during conservative treatment explain changes in clinical outcomes related to nonspecific low back pain? A systematic review.

J Pain 2014 Apr 1;15(4):377.e1-35. Epub 2013 Nov 1.

Department of Physical Therapy, University of Alberta, Edmonton, Alberta, Canada. Electronic address:

Unlabelled: Previous research describes an inconsistent relation between temporal changes in transversus abdominis or lumbar multifidus and temporal changes in clinical outcomes. Unfortunately, a relevant systematic review is unavailable. As a result, this systematic review was designed to summarize evidence regarding the association between temporal changes in muscle morphometry and activity in response to treatment, and temporal changes in clinical outcomes. Candidate publications were identified from 6 electronic databases. Fifteen articles were included after scrutinization by 2 reviewers using predetermined selection criteria. The methodological quality of these articles was appraised using a standard tool. These methods revealed strong evidence that temporal alterations in transversus abdominis thickness change during contraction (as measured by B-mode or M-mode ultrasound) or feedforward activation of transversus abdominis (assessed via electromyography, tissue Doppler imaging, or M-mode ultrasound) were unrelated to temporal changes in low back pain (LBP)/LBP-related disability. There was limited evidence that temporal changes in transversus abdominis lateral sliding or lumbar multifidus endurance were unrelated to temporal changes in LBP intensity. Conflicting evidence was found for the relation between temporal changes in lumbar multifidus morphometry and temporal changes in LBP/LBP-related disability. This review highlights that temporal changes in transversus abdominis features tend to be unrelated to the corresponding LBP/LBP-related disability improvements, whereas the relation between multifidus changes and clinical improvements remains uncertain.

Perspective: This systematic review highlighted that changes in morphometry or activation of transversus abdominis following conservative treatments tend not to be associated with the corresponding changes in clinical outcomes. The relation between posttreatment changes in characteristics of lumbar multifidus and clinical improvements remains uncertain.
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http://dx.doi.org/10.1016/j.jpain.2013.10.008DOI Listing
April 2014

Do various baseline characteristics of transversus abdominis and lumbar multifidus predict clinical outcomes in nonspecific low back pain? A systematic review.

Pain 2013 Dec 16;154(12):2589-2602. Epub 2013 Jul 16.

Department of Physical Therapy, University of Alberta, Edmonton, Alberta, Canada Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada Sansom Institute for Health Research, School of Health Sciences, University of South Australia, Adelaide, South Australia, Australia.

Although individual reports suggest that baseline morphometry or activity of transversus abdominis or lumbar multifidus predict clinical outcome of low back pain (LBP), a related systematic review is unavailable. Therefore, this review summarized evidence regarding the predictive value of these muscular characteristics. Candidate publications were identified from 6 electronic medical databases. After review, 5 cohort studies were included. Although this review intended to encompass studies using different muscle assessment methods, all included studies coincidentally used ultrasound imaging. No research investigated the relation between static morphometry and clinical outcomes. Evidence synthesis showed limited evidence supporting poor baseline transversus abdominis contraction thickness ratio as a treatment effect modifier favoring motor control exercise. Limited evidence supported that high baseline transversus abdominis lateral slide was associated with higher pain intensity after various exercise interventions at 1-year follow-up. However, there was limited evidence for the absence of relation between the contraction thickness ratio of transversus abdominis or anticipatory onset of lateral abdominal muscles at baseline and the short- or long-term LBP intensity after exercise interventions. There was conflicting evidence for a relation between baseline percent thickness change of lumbar multifidus during contraction and the clinical outcomes of patients after various conservative treatments. Given study heterogeneity, the small number of included studies and the inability of conventional greyscale B-mode ultrasound imaging to measure muscle activity, our findings should be interpreted with caution. Further large-scale prospective studies that use appropriate technology (ie, electromyography to assess muscle activity) should be conducted to investigate the predictive value of morphometry or activity of these muscles with respect to LBP-related outcomes measures.
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http://dx.doi.org/10.1016/j.pain.2013.07.010DOI Listing
December 2013
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