In vivo measurement of intradiscal pressure changes related to thrust and non-thrust spinal manipulation in an animal model: a pilot study.

BACKGROUND: The intervertebral disc is a known back pain generator and is frequently the focus of spinal manipulative therapy evaluation and treatment. The majority of our current knowledge regarding intradiscal pressure (IDP) changes related to spinal manual therapy involves cadaveric studies with their inherent limitations. Additional in vivo animal models are needed to investigate intervertebral disc physiological and molecular mechanisms related to spinal manipulation and spinal mobilization treatment for low back disorders. METHODS: Miniature pressure catheters (Millar SPR-1000) were inserted into either the L4-L5 or L5-L6 intervertebral disc of 3 deeply anesthetized adult cats (Oct 2012-May 2013). Changes in IDP were recorded during delivery of instrument-assisted spinal manipulation (Activator V® and Pulstar®) and motorized spinal flexion with/without manual spinous process contact. RESULTS: Motorized flexion of 30° without spinous contact decreased IDP of the L4-L5 disc by ~ 2.9 kPa, while physical contact of the L4 spinous process decreased IDP an additional ~ 1.4 kPa. Motorized flexion of 25° with L5 physical contact in a separate animal decreased IDP of the L5-L6 disc by ~ 1.0 kPa. Pulstar® impulses (setting 1-3) increased IDP of L4-L5 and L5-L6 intervertebral discs by ~ 2.5 to 3.0 kPa. Activator V® (setting 1-4) impulses increased L4-L5 IDP to a similar degree. Net changes in IDP amplitudes remained fairly consistent across settings on both devices regardless of device setting suggesting that viscoelastic properties of in vivo spinal tissues greatly dampen superficially applied manipulative forces prior to reaching deep back structures such as the intervertebral disc. CONCLUSIONS: This study marks the first time that feline in vivo changes in IDP have been reported using clinically available instrument-assisted spinal manipulation devices and/or spinal mobilization procedures. The results of this pilot study indicate that a feline model can be used to investigate IDP changes related to spinal manual therapy mechanisms as well as the diminution of these spinal manipulative forces due to viscoelastic properties of the surrounding spinal tissues. Additional investigation of IDP changes is warranted in this and/or other in vivo animal models to provide better insights into the physiological effects and mechanisms of spinal manual therapy at the intervertebral disc level.

Characteristics of Paraspinal Muscle Spindle Response to Mechanically Assisted Spinal Manipulation: A Preliminary Report.

OBJECTIVES: The purpose of this preliminary study is to determine muscle spindle response characteristics related to the use of 2 solenoid powered clinical mechanically assisted manipulation (MAM) devices. METHODS: L6 muscle spindle afferents with receptive fields in paraspinal muscles were isolated in 6 cats. Neural recordings were made during L7 MAM thrusts using the Activator V (Activator Methods Int. Ltd., Phoenix, AZ) and/or Pulstar (Sense Technology Inc., Pittsburgh, PA) devices at their 3 lowest force settings. Mechanically assisted manipulation response measures included (a) the time required post-thrust until the first action potential, (b) differences in mean frequency (MF) and mean instantaneous frequency (MIF) 2 seconds before and after MAM, and (c) the time required for muscle spindle discharge (MF and MIF) to return to 95% of baseline after MAM. RESULTS: Depending on device setting, between 44% to 80% (Pulstar) and 11% to 63% (Activator V) of spindle afferents required >6 seconds to return to within 95% of baseline MF values; whereas 66% to 89% (Pulstar) and 75% to 100% (Activator V) of spindle responses returned to within 95% of baseline MIF in <6 seconds after MAM. Nonparametric comparisons between the 22 N and 44 N settings of the Pulstar yielded significant differences for the time required to return to baseline MF and MIF. CONCLUSION: Short duration (<10 ms) MAM thrusts decrease muscle spindle discharge with a majority of afferents requiring prolonged periods (>6 seconds) to return to baseline MF activity. Physiological consequences and clinical relevance of described MAM mechanoreceptor responses will require additional investigation.

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.

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.

Chiropractic Distraction Spinal Manipulation on Postsurgical Continued Low Back and Radicular Pain Patients: A Retrospective Case Series.

PURPOSE: The purpose of this case series is to report on changes in pain levels experienced by 69 postsurgical continued pain patients who received Cox Technic Flexion Distraction (CTFD). METHODS: Fifteen doctors of chiropractic collected retrospective data from the records of the postsurgical continued pain patients seen in their clinic from February to July 2012 who were treated with CTFD, which is a type of chiropractic distraction spinal manipulation. Informed consent was obtained from all patients who met the inclusion criteria for this study. Data recorded included subjective patient pain levels at the end of the treatments provided and at 24 months following the last treatment. RESULTS: Fifty-four (81%) of the patients showed greater than 50% reduction in pain levels at the end of the last treatment, and 13 (19%) showed less than 50% improvement of pain levels at the end of active care (mean, 49 days and 11 treatments). At 24-month follow-up, of 56 patients available, 44 (78.6%) had continued pain relief of greater than 50% and 10 (18%) reported 50% or less relief. The mean percentage of relief at the end of active care was 71.6 (SD, 23.2) and at 24 months was 70 (SD, 25). At 24 months after active care, 24 patients (43%) had not sought further care, and 32 required further treatment consisting of chiropractic manipulation for 17 (53%), physical therapy, exercise, injections, and medication for 9 (28%), and further surgery for 5 (16%). CONCLUSION: Greater than 50% pain relief following CTFD chiropractic distraction spinal manipulation was seen in 81% of postsurgical patients receiving a mean of 11 visits over a 49-day period of active care.

Similar Effects of Thrust and Nonthrust Spinal Manipulation Found in Adults With Subacute and Chronic Low Back Pain: A Controlled Trial With Adaptive Allocation.

STUDY DESIGN: A three-arm controlled trial with adaptive allocation. OBJECTIVES: The aim of this study was to compare short-term effects of a side-lying, thrust spinal manipulation (SM) procedure and a nonthrust, flexion-distraction SM procedure in adults with subacute or chronic low back pain (LBP) over 2 weeks. SUMMARY OF BACKGROUND DATA: SM has been recommended in recently published clinical guidelines for LBP management. Previous studies suggest that thrust and nonthrust SM procedures, though distinctly different in joint loading characteristics, have similar effects on patients with LBP. METHODS: Participants were eligible if they were 21 to 54 years old, had LBP for at least 4 weeks, scored 6 or above on the Roland-Morris disability questionnaire, and met the diagnostic classification of 1, 2, or 3 according to the Quebec Task Force Classification for Spinal Disorders. Participants were allocated in a 3:3:2 ratio to four sessions of thrust or nonthrust SM procedures directed at the lower lumbar and pelvic regions, or to a 2-week wait list control. The primary outcome was LBP-related disability using Roland-Morris Disability Questionnaire and the secondary outcomes were LBP intensity using visual analog scale, Fear-Avoidance Beliefs Questionnaire, and the 36-Item Short Form Health Survey. The study was conducted at the Palmer Center for Chiropractic Research with care provided by experienced doctors of chiropractic. Clinicians and patients were not blinded to treatment group. RESULTS: Of 192 participants enrolled, the mean age was 40 years and 54% were male. Improvement in disability, LBP intensity, Fear-Avoidance Beliefs Questionnaire-work subscale, and 36-Item Short Form Health Survey-physical health summary measure for the two SM groups were significantly greater than the control group. No difference in any outcomes was observed between the two SM groups. CONCLUSION: Thrust and nonthrust SM procedures with distinctly different joint loading characteristics demonstrated similar effects in short-term LBP improvement and both were superior to a wait list control. LEVEL OF EVIDENCE: 2.

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.

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.

Chiropractic and self-care for back-related leg pain: design of a randomized clinical trial.

BACKGROUND: Back-related leg pain (BRLP) is a common variation of low back pain (LBP), with lifetime prevalence estimates as high as 40%. Often disabling, BRLP accounts for greater work loss, recurrences, and higher costs than uncomplicated LBP and more often leads to surgery with a lifetime incidence of 10% for those with severe BRLP, compared to 1-2% for those with LBP.In the US, half of those with back-related conditions seek CAM treatments, the most common of which is chiropractic care. While there is preliminary evidence suggesting chiropractic spinal manipulative therapy is beneficial for patients with BRLP, there is insufficient evidence currently available to assess the effectiveness of this care. METHODS/DESIGN: This study is a two-site, prospective, parallel group, observer-blinded randomized clinical trial (RCT). A total of 192 study patients will be recruited from the Twin Cities, MN (n = 122) and Quad Cities area in Iowa and Illinois (n = 70) to the research clinics at WHCCS and PCCR, respectively.It compares two interventions: chiropractic spinal manipulative therapy (SMT) plus home exercise program (HEP) to HEP alone (minimal intervention comparison) for patients with subacute or chronic back-related leg pain. DISCUSSION: Back-related leg pain (BRLP) is a costly and often disabling variation of the ubiquitous back pain conditions. As health care costs continue to climb, the search for effective treatments with few side-effects is critical. While SMT is the most commonly sought CAM treatment for LBP sufferers, there is only a small, albeit promising, body of research to support its use for patients with BRLP.This study seeks to fill a critical gap in the LBP literature by performing the first full scale RCT assessing chiropractic SMT for patients with sub-acute or chronic BRLP using important patient-oriented and objective biomechanical outcome measures. TRIAL REGISTRATION: ClinicalTrials.gov NCT00494065.

The reliability of a posterior-to-anterior spinal stiffness measuring system in a population of patients with low back pain.

OBJECTIVE: A system for measuring posterior-to-anterior spinal stiffness (PAS) was developed for use in clinical trials of manipulation for low back pain. The reliability of this device is under investigation in this study. METHODS: The PAS system uses electronic sensors to record displacement and force while a human operator provides the force of indentation. A test-retest design was used with measures repeated by the same operator within 5 minutes. Posterior-to-anterior loads were applied to each lumbar spinous process of patients lying prone on a hard flat bench. Force and displacement were recorded and used to calculate PAS. RESULTS: The subjects consisted of 22 males and 14 females; average age was 49.1 years (SD, 14.2). All subjects had low back pain of at least 4 weeks duration, with mean Roland-Morris scores of 7.6 (SD, 3.3). Spinal stiffness ranged from 4 to 26 N/mm (average, 11.2; SD, 3.5). Stiffness in the first and second tests varied on the average by 0.31 N/mm (P = .03). Standard error of the measurement was 1.62 N/mm. The single measures intraclass correlation coefficient (3,1) was 0.790 (95% confidence interval, 0.739-0.832). CONCLUSIONS: The equipment and method produced repeatable results over the short-term. The system may be sensitive enough to detect changes in spinal stiffness that occur with care.