Low-amplitude Spinal Manipulation Research Articles

Effects of High-Velocity Spinal Manipulation on Quality of Life, Pain and Spinal Curvature in Children with Idiopathic Scoliosis: A Systematic Review.

Scoliosis is a condition that involves deformation of the spine in the coronal plane and commonly appears in childhood or adolescence, significantly limiting a person's life. The cause is multifactorial, and treatment aims to improve the spinal curvature, prevent major pathologies, and enhance aesthetics. The objective of this review was to determine whether high-velocity low-amplitude (HVLA) spinal manipulation is more effective than other treatments for children with idiopathic scoliosis (IS). The PubMed, Web of Science, Scopus and PEDro databases were searched for both clinical trials and cohort studies. Methodological quality was assessed via the PEDro scale (for clinical trials) and the Newcastle-Ottawa scale (for observational studies). The protocol of this systematic review was registered in PROSPERO (CRD42024532442). Five studies were selected for review. The results indicated moderate improvements in pain and the Cobb angle and limited improvements in quality of life. HVLA spinal manipulation does not seem to have significant effects on reducing spinal deformity in IS patients, nor does it significantly impact quality of life. However, this therapy may have significant effects on reducing pain in these patients.

THE EFFECT OF SINGLE HIGH-VELOCITY, LOW-AMPLITUDE SPINE MANIPULATION ON POSTURE, FUNCTIONAL STATE OF TORSO, THIGH MUSCLES, AND VERTICAL JUMP HEIGHT

The effects impact of single high-velocity, low-amplitude (HVLA) spinal manipulation on posture, torso, and thigh functional condition, and the height of the vertical jump have not been adequately studied. The research aims to investigate the immediate changes caused by a single spinal vertebral HVLA manipulation 3 weeks after posture, torso, and thigh muscle functional state, and vertical jump height. The study involved 46 men aged 18-25 years old who practiced indoor volleyball training at least twice a week, as well as a deviation of the vertebral vertebrae from the non-thymic position. Initially, posture was assessed using the photogrammetry method and muscle length was assessed using the goniometry method. A vertical jump height test was performed by the Sargent Jump test. A single HVLA spinal manipulation was performed by a certified chiropractor for segment correction. Then, a re-assessment of posture (photogrammetry), re-assessment of movement volume (goniometry) as well a re-assessment of vertical jump height test- the Sargent Jump test was performed. After 3 weeks post HVLA manipulation participants were retested. The main findings are: immediately after the HVLA spinal correction changes in posture were observed in all evaluated parameters, deviations from the norm decreased by 25.45% ± 1.27% (p < .005), while the vertical jump height test results immediately after HVLA increased by 4.34% ± 0.11% (p < .005). After 3 weeks post HVLA spine manipulation therapeutic effect was reduced by 5.48% ± 1.27% (p < .005), while the Sargent Jump test result 3 weeks after manipulation decreased by 0.05% ± 0.11% (p > .005). Conclusion: the persistence of the effect of a single HVLA spine manipulation was maintained for 3 weeks after the manipulation into the posture.

Comparison of Forces Exerted by a Chiropractor on Children and Adults During High-Speed, Low-Amplitude Spinal Manipulations: A Feasibility Study

ObjectiveThe aim of this study was to demonstrate that quantification of the forces exerted by a single chiropractor on children and adults during high-velocity, low-amplitude spinal manipulations and the correlation of forces to age was feasible. MethodsThe force-time profiles of high-velocity, low-amplitude spinal manipulations were measured in 48 children (109 manipulations) ranging from 14 weeks to 17 years of age, and 20 adults (49 manipulations) in a clinical setting. The measurements were taken using a thin, flexible pressure pad. Outcome variables (peak forces, preload forces, thrust forces, thrust durations, rates of force application, and thrust impulses) were quantified and compared across age groups using Kruskal-Wallis testing with Dunn post hoc analysis. Outcome variables were fitted with best-fitting linear regressions with age as the dependent variable. The level of significance for all statistical tests was set a priori at α = 0.05. ResultsMost outcome variables increased with the age of the patient. Specifically, peak forces, thrust forces, and the rate of force application were positively correlated with age, while thrust durations remained constant across all ages and preload forces decreased slightly with patient age for cervical spine manipulations. ConclusionFor this single chiropractor in private practice, the forces he used increased with the age of the patient, and he thus used lower forces in children than adults. This study shows that measuring the forces used by a chiropractor in clinical practice on patients with a range of ages was feasible.

Electromyographic Responses of Neck, Back, and Limb Outlet Muscles Associated With High-Velocity, Low-Amplitude Manual Cervical and Upper Thoracic Spinal Manipulation of Individuals With Mild Neck Disability: A Descriptive Observational Investigation

ObjectivesThe purpose of this study was to investigate the extent of electromyographic responses associated with manual high-velocity, low-amplitude (HVLA) spinal manipulation systematically applied to the upper and lower cervical and upper thoracic spines in a cohort with mild neck disability. MethodsThe study was a descriptive observational investigation, with all participants receiving the same interventions. Nineteen participants with mild neck disability received 6 manual HVLA manipulations to the cervical and upper thoracic spine. Bipolar surface electromyography electrode pairs were used to measure responses of 16 neck, back, and limb outlet muscles bilaterally. The number of electromyographic responses was then calculated. ResultsElectromyographic responses associated with cervical and thoracic manipulation occurred in a median of 4 of the 16 (range: 1-14) recorded muscles. Cervical spinal manipulation was associated with the highest rates of electromyographic responses in neck muscles, whereas responses in back muscles were highest after upper thoracic manipulation. ConclusionCervical spinal manipulation was associated with the highest rate of electromyographic responses in muscles of the cervical spine (sternocleidomastoid and splenius cervicis), whereas responses in back muscles (upper and middle trapezius, latissimus dorsi, and longissimus thoracis) were highest after upper thoracic manipulations. This result suggests that electromyographic muscular responses associated with spinal manipulation primarily occur locally (close to the target segment) rather than distally.

Radiography and Clinical Decision-Making in Chiropractic.

The concern over x-ray exposure risks can overshadow the potential benefit of radiography, especially in cases where manual therapy is employed. Spinal malalignment cannot be accurately visualized without imaging. Manual therapy and the load tolerances of injured spinal tissues raise different criteria for the use of x-rays for spinal disorders than in medical practice. Current regulatory bodies rely on radiography risk assessments based on Linear-No-Threshold (LNT) risk models. There is a need to consider radiography guidelines for chiropractic which are different from those for medical practice. Radiography practice guidelines are summaries dominated by frequentist interpretations in the analysis of data from studies. In contrast, clinicians often employ a pseudo-Bayesian form of reasoning during the clinical decision-making process. The overrepresentation of frequentist perspectives in evidence-based practice guidelines alter decision-making away from practical assessment of a patient’s needs, toward an overly cautious standard applied to patients without regard to their risk/benefit likelihoods relating to radiography. Guidelines for radiography in chiropractic to fully assess the condition of the spine and spinal alignment prior to manual therapy, especially with high velocity, low amplitude spinal manipulation (HVLA-SM), should necessarily differ from those used in medical practice.

Influence of Intervertebral Fixation and Segmental Thrust Level on Immediate Post-Spinal Manipulation Trunk Muscle Spindle Response in an Animal Model.

Objective: To characterize the effect of unilateral (single and two-level) lumbar facet/zygapophysial joint fixation on paraspinal muscle spindle activity immediately following L4 or L6 high velocity low amplitude spinal manipulation (HVLA-SM) delivered at various thrust durations. Methods: Secondary analysis of immediate (≤2 s) post-HVLA-SM trunk muscle spindle response from two studies involving anesthetized adult cats (n = 39; 2.3–6.0 kg) with either a unilateral single (L5/6) or two-level (L5/6 and L6/7) facet joint fixation. All facet fixations were contralateral to L6 dorsal root recordings. HVLA-SM was delivered to the spinous process in a posterior-to-anterior direction using a feedback motor with a peak thrust magnitude of 55% of average cat body weight and thrust durations of 75, 100, 150, and 250 ms. Time to 1st action potential and spindle activity during 1 and 2 s post-HVLA-SM comparisons were made between facet joint fixation conditions and HVLA-SM segmental thrust levels. Results: Neither two-level facet joint fixation, nor HVLA-SM segmental level significantly altered immediate post-HVLA-SM spindle discharge at tested thrust durations (FDR > 0.05). Conclusions: Two-level facet joint fixation failed to alter immediate (≤2 s) post-HVLA-SM spindle discharge when compared to single-level facet joint fixation at any thrust duration. Segmental thrust level did not alter immediate post-HVLA-SM spindle response in two-level facet joint fixation preparations.

Effects of Thrust Magnitude and Duration on Immediate Postspinal Manipulation Trunk Muscle Spindle Responses

ObjectiveThe purpose of this study was to characterize trunk muscle spindle responses immediately after high-velocity, low-amplitude spinal manipulation (HVLA-SM) delivered at various thrust magnitudes and thrust durations. MethodsSecondary analysis from multiple studies involving anesthetized adult cats (N = 70; 2.3-6.0 kg) receiving L6 HVLA-SM. Muscle spindle afferent recordings were obtained from L6 dorsal rootlets before, during, and immediately after HVLA-SM. L6 HVLA-SM was delivered posteriorly-to-anteriorly using a feedback motor with peak thrust magnitudes of 25%, 55%, and 85% of cat body weight (BW) and thrust durations of 25, 50, 75, 100, 150, 200, and 250 ms. Time to the first action potential and muscle spindle discharge frequency at 1 and 2 seconds post–HVLA-SM were determined. ResultsA significant association between HVLA-SM thrust magnitude and immediate (≤2 s) muscle spindle response was found (P < .001). For non-control thrust magnitude, pairwise comparisons (25%, 55%, 85% BW), 55% BW thrust magnitude had the most consistent effect on immediate post–HVLA-SM discharge outcomes (false discovery rate < 0.05). No significant association was found between thrust duration and immediate post–HVLA-SM muscle spindle response (P > .05). ConclusionThe present study found that HVLA-SM thrust magnitudes delivered at 55% BW were more likely to affect immediate (≤2 s) post–HVLA-SM muscle spindle response.

16 Preliminary investigation into the effects of McTimoney chiropractic treatment and combined with pulsed electromagnetic field therapy on mechanical nociceptive thresholds of horses

McTimoney chiropractic treatment(MCT), a high velocity low amplitude spinal manipulation therapy, produces profound but transient attenuation of motor neurone activity. Pulsed electromagnetic field therapy(PEMF) has perceived pain-relieving effects and improves the reduction in muscle and fascial tension. Both are used in therapeutic protocols. The study objectively assessed the influence of MCT and PEMF therapy on mechanical nociceptive thresholds(MNTs) at 3 specific muscular junction trigger points(TPs) of the thoracolumbar musculature. MNTs are a measure of sensitivity to musculoskeletal tenderness. A controlled randomized study using 12 sound cob-type horses from the same yard and training schedule randomly assigned into 3 groups of n = 4. Control group, no intervention; 2 treatment groups:(A) MCT only (10min assessment, 10min treatment by a qualified McTimoney animal practitioner) and (B) combined (MCT plus Biomag 2TM PEMF mat(200hz) placed cranial to T18, 5min per side). Stood square, triplicate MNTs were measured using pressure algometry on both sides at 3 muscle TPs[TP 45(junction of spinalis, longissimus thoracis and trapezius thoracis); 47 (longissimus thoracis et lumborum); and 62 (gluteus medius)] at 4 time points 0(pre-treatment), 30(post MCT), 60(post PEMF), 150min.Statistical tests: Shapiro-Wilk test, paired T- test compared left/right MNTs, ANOVA analyzed group data for each TP over time with Bonferroni post hoc analysis. There was no difference (P > 0.05) between left and right MNTs for all measurement sites. There was no changes in MNTs over time at all TPs for control group(P > 0.05). There was a significant increase in mean MNTs pre-treatment to 150min for both treatment groups (A:P = 0.03, B:P = 0.01). Significant changes in MNTs at each muscle TP shown in Table 1. This study provides positive evidence that chiropractic and when combined with PEMF treatment show a significant reduction in sensitivity to musculoskeletal tenderness (increased MNTs) over the time period compared with no treatment. Different muscle groups behave differently. Further research is required on difference in muscle tonicity effects and over a longer period.

Developing a standardized curriculum for teaching chiropractic technique.

This is a report of the results of 4 facilitated workshops aimed at developing a standardized chiropractic technique curriculum. Workshops were held at research conferences during 2014, 2016, 2018, and 2019. Participants were tasked with developing recommendations for diagnostic and therapeutic procedures appropriate for chiropractic technique programs. For diagnostic procedures, there was general agreement among participants that chiropractic programs should include diagnostic imaging, postural assessment, gait analysis, palpation (static, motion, and joint play/springing), global range of motion, and evidence-based orthopedic/neurological tests. No consensus could be reached with respect to chiropractic x-ray line marking (spinography) nor heat sensing instruments, and there was only partial consensus on leg length assessment. For therapeutic procedures, all participants agreed that the following should be included: high-velocity, low amplitude spinal and extremity manipulation, adjustments assisted by hand-held instruments, drop tables, flexion-distraction tables, and pelvic blocks. There was unanimous support for teaching mobilization of the spine and peripheral joints, as well as for manual and instrument-assisted soft tissue therapies. There were some overarching issues: participants strongly preferred assessment methods known to be reliable and valid and therapeutic procedures known to be safe and effective. Where evidence was lacking, they insisted that diagnostic and therapeutic methods at minimum have face validity and biological plausibility. However, they cautioned against applying aspects of evidence-based care too rigidly. Despite differing views on chiropractic terminology, philosophy, and scope of practice, participants' opinions were similar regarding diagnostic and therapeutic procedures that ought to be included in chiropractic technique programs.

Rupture Risk Assessment of Cervical Spinal Manipulations on Carotid Atherosclerotic Plaque by a 3D Fluid-Structure Interaction Model.

Method The FSI model, based on MRI data of an atherosclerosis patient, was used to simulate the deformations of the plaque and lumen during the process of two kinds of typical cSMT (the high-speed, low-amplitude spinal manipulation and the cervical rotatory manipulation). The biomechanical parameters were recorded, such as the highest wall shear stress (WSS), the maximum plaque wall stress (PWS), the wall tensile stress (Von mises stress, VWTS), and the strain. Result The max_WSS was 33.77 kPa in the most extensive deformation. The highest WSS region on the plaque surface was also the highest PWS region. The max_PWS in a 12% stretch was 55.11 kPa, which was lower than the rupture threshold. The max_VWTS of the cap in 12% stretch which approached the fracture stress level was 116.75 kPa. Moreover, the vessel's max_VWTS values in 10% and 12% stretch were 554.21 and 855.19 kPa. They were higher than the fracture threshold, which might cause media fracture. Meanwhile, the 7% stretched strain was 0.29, closed to the smallest experimental green strains at rupture. Conclusion The carotid arteries' higher stretch generated the higher stress level of the plaque. Cervical rotatory manipulation might cause plaque at a high risk of rupture in deformation after 12% stretch and more. Lower deformation of the plaque and artery caused by the high-speed, low-amplitude spinal manipulation might be safer.

Differences in force-time parameters and electromyographic characteristics of two high-velocity, low-amplitude spinal manipulations following one another in quick succession

BackgroundSpinal manipulative therapy is an effective treatment for neck pain. However, the mechanisms underlying its clinical efficacy are not fully understood. Previous studies have not systematically compared force-time parameters and electromyographic responses associated with spinal manipulation. In this study, force-time parameters and electromyographic characteristics associated with multiple manual high-velocity, low-amplitude cervical and upper thoracic spinal manipulations were investigated. The purpose of this analysis was to compare the force-time parameters and electromyographic characteristics between two spinal manipulations delivered following one another in quick succession if the first thrust was not associated with an audible cavitation.MethodsNine asymptomatic and eighteen symptomatic participants received six Diversified-style spinal manipulations to the cervical and upper thoracic spines during data collected February 2018 to September 2019. Peak force, rate of force application and thrust duration were measured using a pressure pad. Bipolar surface electrodes were used to measure the electromyographic responses and reflex delay times in sixteen neck, back and limb outlet muscles bilaterally. Differences in force-time parameters and electromyographic data were analyzed between the first and second thrust.ResultsFifty-two spinal manipulations were included in this analysis. Peak force was greater (p < 0.001) and rate of force application faster (p < 0.001) in the second thrust. Furthermore, peak electromyographic responses were higher following the second thrust in asymptomatic (p < 0.001) and symptomatic (p < 0.001) subjects. Also, electromyographic delays were shorter in the symptomatic compared to the asymptomatic participants for the second thrust (p = 0.039). There were no adverse patient events.ConclusionWhen a second manipulation was delivered because there was not audible cavitation during the first thrust, the second thrust was associated with greater treatment forces and faster thrust rates. Peak electromyographic responses were greater following the second thrust.

Predictors of instantaneous relief from spinal manipulation for non-specific low back pain: a delphi study

BackgroundThere is some evidence and anecdotal reports that high-velocity low-amplitude (HVLA) spinal manipulation therapy (SMT) for non-specific low back pain (NSLBP) may immediately reduce pain in some patients. The mechanism for such a change remains unclear and the evidence is conflicting. The aim of this study was to seek consensus among a sample of expert manual therapists as to the possible clinical predictors that could help identify patients who are most likely to receive instant relief from NSLBP with SMT intervention.MethodsThirty-seven expert chiropractors and manipulative physiotherapists from around the world were invited to participate in a three round online Delphi questionnaire during the second half of 2018. Participants were provided with a list of 55 potential signs and symptoms as well as offering them the option of suggesting other factors in the first round. The variables were rated using a 4-point Likert likelihood scale and a threshold of 75% agreement was required for any item to progress to the next round.ResultsOf these 37 experts, 19 agreed to participate. Agreement as to the proportion of patients who receive instantaneous relief was minimal (range 10–80%). A total of 62 items were ranked over the 3 rounds, with 18 of these retained following the third round. The highest rated of the 18 was ‘A history including a good response to previous spinal manipulation’.Discussion/conclusionFive categories; patient factors, practitioner factors, signs and symptoms of NSLBP presentation, an instrument of measurement (FABQ), and the presence of cavitation following SMT best describe the overall characteristics of the factors. The 18 factors identified in this study can potentially be used to create an instrument of measurement for further study to predict those patients with NSLBP who will receive instantaneous relief post-SMT.

Does manual therapy affect functional and biomechanical outcomes of a sit-to-stand task in a population with low back pain? A preliminary analysis

IntroductionManual therapy (MT) hypothetically affects discrepant neuromuscular control and movement observed in populations with low back pain (LBP). Previous studies have demonstrated the limited influence of MT on movement, predominately during range of motion (ROM) testing. It remains unclear if MT affects neuromuscular control in mobility-based activities of daily living (ADLs). The sit-to-stand (STS) task represents a commonly-performed ADL that is used in a variety of clinical settings to assess functional and biomechanical performance.ObjectiveTo determine whether MT affects functional performance and biomechanical performance during a STS task in a population with LBP.MethodsKinematic data were recorded from the pelvis and thorax of participants with LBP, using an optoelectronic motion capture system as they performed a STS task before and after MT from November 2011 to August 2014. MT for each participant consisted of two high-velocity low-amplitude spinal manipulations, as well as two grade IV mobilizations of the lumbar spine and pelvis targeted toward the third lumbar vertebra and sacroiliac joint in a side-lying position; the order of these treatments was randomized. Pelvis and thorax kinematic data were used to derive the time-varying lumbar angle in the sagittal plane for each STS trial. The difference between the maximum and minimum lumbar angles during the STS trial determined the sagittal ROM that was used as the biomechanical outcome. Time to complete each STS trial was used as a functional measure of performance. Pre-MT and post-MT values for the lumbar sagittal ROM and time to completion were statistically analysed using paired samples t-tests.ResultsData were obtained from 40 participants with 35 useful datasets (NRS = 3.3 ± 1.2; 32.4 ± 9.8 years; 16 females, 19 males). After MT, lumbar sagittal ROM increased by 2.7 ± 5.5 degrees (p = 0.007). Time to complete the STS test decreased by 0.4 ± 0.4 s (p < 0.001).DiscussionThese findings provide preliminary evidence that MT might influence the biomechanical and functional performance of an STS task in populations with LBP. The MT intervention in this study involved a combination of spinal manipulations and mobilizations. Future work will expand upon these data as a basis for targeted investigations on the effects of either spinal manipulation and mobilization on neuromuscular control and movement in populations with LBP.

The effect of a single spinal manipulation on cardiovascular autonomic activity and the relationship to pressure pain threshold: a randomized, cross-over, sham-controlled trial

BackgroundThe autonomic nervous system interacts with the pain system. Knowledge on the effects of high velocity low amplitude spinal manipulations (SM) on autonomic activity and experimentally induced pain is limited. In particular, the effects of SM on autonomic activity and pain beyond the immediate post intervention period as well as the relationship between these two outcomes are understudied. Thus, new research is needed to provide further insight on this issue.ObjectivesThe aim was to assess the effect of a single SM (i.e. SM vs. sham) on cardiovascular autonomic activity. Also, we assessed the relationship between cardiovascular autonomic activity and level of pain threshold after the interventions.MethodWe conducted a randomized, cross-over, sham-controlled trial on healthy first-year chiropractic students comprising two experimental sessions separated by 48 h. During each session, subjects received, in a random order, either a thoracic SM or a sham manipulation. Cardiovascular autonomic activity was assessed using heart rate and systolic blood pressure variabilities. Pain sensitivity was assessed using pressure pain threshold. Measurements were performed at baseline and repeated three times (every 12 min) during the post intervention period. Participants and outcome assessors were blinded. The effect of the SM was tested with linear mixed models. The relationship between autonomic outcomes and pressure pain threshold was tested with bivariate correlations.ResultsFifty-one participants were included, forty-one were finally analyzed. We found no statistically significant difference between SM and sham in cardiovascular autonomic activity post intervention. Similarly, we found no post-intervention relationship between cardiovascular autonomic activity and pressure pain threshold.ConclusionOur results suggest that a single SM of the thoracic spine has no specific effect on cardiovascular autonomic activity. Also, we found no relationship between cardiovascular autonomic activity and pressure pain threshold after the SM. Further experimental research should consider the use of several markers of autonomic activity and a more comprehensive pain assessment.Trial registrationN° NCT03273868. Registered September 6, 2017.

Neurophysiological Effects of High Velocity and Low Amplitude Spinal Manipulation in Symptomatic and Asymptomatic Humans: A Systematic Literature Review.

Systematic review. To summarize the evidence of neurophysiological effects of spinal manipulative therapy (SMT) with a high velocity low amplitude thrust (HVLA-SMT) in asymptomatic and symptomatic humans. HVLA-SMT is effective in reducing back pain, but its mode of action is not fully understood. A systematic literature search (until July 2018) was conducted by a professional librarian in seven databases (Medline (OvidSP), Premedline (PubMed), EMBASE, Cochrane, CINAHL, PEDro, and Scopus). Two authors selected the studies according to the a priori described criteria and scored study quality. Only controlled studies of at least moderate quality were included. Effects of HVLA-SMT on a particular outcome measure were defined as more than one study showing a significantly greater effect of HVLA-SMT compared with the control intervention. From the 18 studies included (932 participants in total), there was evidence only for an association between HVLA-SMT and changes in the autonomic nervous system, reflected in changes in heart rate variability and skin conductance. Most studies focused on healthy volunteers and none related neurophysiologic changes to pain reduction. This systematic review points to HVLA-SMT affecting the autonomic nervous system. The effects seem to depend on the spinal level of HVLA-SMT application and might differ between healthy volunteers and pain patients. There is a need for high-quality studies that include patients, well characterized for pain duration and outcome measure baseline values, and address the relation between changes in neurophysiology and pain. 2.

Force transmission between thoracic and cervical segments of the spine during prone-lying high-velocity low-amplitude spinal manipulation: A proof of principle for the concept of regional interdependence

BackgroundRegional interdependence is conceptually based on observations that applying manual therapy to a remote anatomical region has an effect in the area of the patient's primary complaint. The current model for regional interdependence depends on force transmissibility within the body. This investigation sought to determine transmissibility between forces applied to the thoracic spine during prone-lying high-velocity low-amplitude spinal manipulative therapy and the cervical spine. MethodsA chiropractic treatment table was modified to allow (or disallow) translation of the headrest in the caudal-cephalad direction when unlocked (or locked). Prone-lying high-velocity low-amplitude spinal manipulative therapy was applied to the thoracic region of 9 healthy participants with the headrest in both configurations. Head and thorax kinematics and kinetics were measured at interfaces between participant and the external environment, which included the clinician's hands. Compressive forces at the cervicothoracic junction and angular kinematics of the cervical spine were derived. Ratios between the clinician-applied forces (input) and the cervical compressive force (output) were also determined. FindingsThe cervical spine extended during all high-velocity low-amplitude spinal manipulative therapy trials. Force input-to-output ratios exceeded 1 for high-velocity low-amplitude spinal manipulative therapy trials performed with the headrest in the locked configuration, which was greater than ratios for the unlocked configuration. InterpretationForces imparted to thoracic spine during high-velocity low-amplitude spinal manipulative therapy were transmitted to the cervical spine, which provided a precursor for the regional interdependence model for manual therapy. Friction between the participant's face and the treatment table's head rest likely amplified cervical compressive forces.

High-velocity, low-amplitude spinal manipulation training of prescribed forces and thrust duration: A pilot study.

High-velocity, low-amplitude spinal manipulation (HVLA-SM) may generate different therapeutic effects depending on force and duration characteristics. Variability among clinicians suggests training to target specific thrust duration and force levels is necessary to standardize dosing. This pilot study assessed an HVLA-SM training program using prescribed force and thrust characteristics. Over 4 weeks, chiropractors and students at a chiropractic college delivered thoracic region HVLA-SM to a prone mannequin in six training sessions, each 30 minutes in duration. Force plates embedded in a treatment table were used to measure force over time. Training goals were 350 and 550 Newtons (N) for peak force and ≤150 ms for thrust duration. Verbal and visual feedback was provided after each training thrust. Assessments included 10 consecutive thrusts for each force target without feedback. Mixed-model regression was used to analyze assessments measured before, immediately following, and 1, 4, and 8 weeks after training. Error from peak force target, expressed as adjusted mean constant error (standard deviation), went from 107 N (127) at baseline, to 0.2 N (41) immediately after training, and 32 N (53) 8 weeks after training for the 350 N target, and 63 N (148), -6 N (58), and 9 N (87) for the 550 N target. Student median values met thrust duration target, but doctors' were >150 ms immediately after training. After participation in an HVLA-SM training program, participants more accurately delivered two prescribed peak forces, but accuracy decreased 1 week afterwards. Future HVLA-SM training research should include follow-up of 1 week or more to assess skill retention.

Motor Neuron Excitability Attenuation as a Sequel to Lumbosacral Manipulation in Subacute Low Back Pain Patients and Asymptomatic Adults: A Cross-Sectional H-Reflex Study

ObjectiveThe purpose of the study was to compare a time series of tibial nerve H-reflex trials between patients with subacute low back pain (LBP) and asymptomatic adults using pre and post high-velocity, low-amplitude (HVLA) spinal manipulation (SM) and control procedures. MethodsAsymptomatic adults (n = 66) and patients with subacute LBP (n = 45) were randomized into 3 lumbosacral procedures: side-posture positioning, joint preloading with no thrust, and HVLA SM. A time series of 40 Hmax/Mmax ratios at a rate of 0.1 Hz were recorded in blocks of 10 trials at baseline and after the lumbosacral procedures at time points corresponding to immediately after, 5 minutes after, and 10 minutes after the procedure. Descriptive time series analysis techniques included time plots, outlier detection, and autocorrelation functions. A mixed analysis of variance model (group × procedure × time) was used to compare the effects of lumbosacral procedures on Hmax/Mmax ratios between the patients with subacute LBP and asymptomatic participants. ResultsThe time series analysis and the significant lumbosacral × time interaction term (P < .05) indicated that inhibition of the Hmax/Mmax ratios at the 10-second postlumbosacral procedure time point was greatest after the HVLA SM procedure. The effects of lumbosacral procedures on Hmax/Mmax ratios were similar between patients with subacute LBP and asymptomatic participants. ConclusionsAlthough nonspecific effects of movement or position artifacts on the Hmax/Mmax ratio were present, a reliable and valid attenuation of the Hmax/Mmax ratio occurred as a specific aspect of HVLA SM in both asymptomatic adults and patients with subacute LBP.

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

Electrophysiological recordings were obtained from proprioceptors in deep lumbar paraspinal muscles of anesthetized cats during high-velocity low-amplitude spinal manipulation (HVLA-SM). To determine how thrust direction of an HVLA-SM affects neural input from back musculature. 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. 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. 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. 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. N/A.

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

ObjectivesThis 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. MethodsTwenty-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. ResultsLumbar 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. ConclusionsThis 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.