Maruti R. Gudavalli

An analytical model of lumbar motion segment in flexion

OBJECTIVE To develop an analytical model of the lumbar motion segment and to determine the following under the application of flexion physiological loads: (1) the force displacement relationships of the lumbar motion segment; (2) the forces in the ligaments, disc, and facet joints; (3) the strains in the ligaments; and (4) the effect of the transection of the ligaments. DESIGN Computer modeling. SETTING Spinal Ergonomics and Joint Research Laboratory at The National College of Chiropractic. PROCEDURE Computer model simulation of external loads and simulation of ligament transection. MEASURES The following parameters were predicted in flexion by means of a computer model: (1) the load-displacement relationships of the lumbar motion segment; (2) the loads in the ligaments, disc and facet joints; (3) the strains in the ligaments; and (4) the effect of the transection of the ligaments. RESULTS The load sharing among different ligaments predicted by this model under flexion load suggests that the supraspinous ligament carries the greatest load, followed by the yellow ligament, capsular ligament, intertransverse ligament, and interspinous ligament. The ligament strains indicate that the supraspinous ligament undergoes the maximum increase in length, followed by the interspinous ligament, yellow ligament, capsular ligament, and intertransverse ligament. The transection of ligaments increased the flexibility of the joint, the strains on the rest of the ligaments, the loads on all of the rest of the ligaments, as well as the moment on the disc, but does not significantly affect the compressive load on the disc. CONCLUSIONS The analytical model predicts results similar to the experimental data on cadaver motion segments reported in the literature under flexion moment loads.

Effect of Sampling Rates on the Quantification of Forces, Durations, and Rates of Loading of Simulated Side Posture High-Velocity, Low-Amplitude Lumbar Spine Manipulation

OBJECTIVE Quantification of chiropractic high-velocity, low-amplitude spinal manipulation (HVLA-SM) may require biomechanical equipment capable of sampling data at high rates. However, there are few studies reported in the literature regarding the minimal sampling rate required to record the HVLA-SM force-time profile data accurately and precisely. The purpose of this study was to investigate the effect of different sampling rates on the quantification of forces, durations, and rates of loading of simulated side posture lumbar spine HVLA-SM delivered by doctors of chiropractic. METHODS Five doctors of chiropractic (DCs) and 5 asymptomatic participants were recruited for this study. Force-time profiles were recorded during (i) 52 simulated HVLA-SM thrusts to a force transducer placed on a force plate by 2 DCs and (ii) 12 lumbar side posture HVLA-SM on 5 participants by 3 DCs. Data sampling rate of the force plate remained the same at 1000 Hz, whereas the sampling rate of the force transducer varied at 50, 100, 200, and 500 Hz. The data were reduced using custom-written MATLAB (Mathworks, Inc, Natick, MA) and MathCad (version 15; Parametric Technologies, Natick, MA) programs and analyzed descriptively. RESULTS The average differences in the computed durations and rates of loading are smaller than 5% between 50 and 1000 Hz sampling rates. The differences in the computed preloads and peak loads are smaller than 3%. CONCLUSIONS The small differences observed in the characteristics of force-time profiles of simulated manual HVLA-SM thrusts measured using various sampling rates suggest that a sampling rate as low as 50 to 100 Hz may be sufficient. The results are applicable to the manipulation performed in this study: manual side posture lumbar spine HVLA-SM.

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

Instantaneous Rate of Loading During Manual High-Velocity, Low-Amplitude Spinal Manipulations

OBJECTIVE The objective of this study was to determine the instantaneous rate of loading during manual high-velocity, low-amplitude spinal manipulations (HVLA SMs) in the lumbar and thoracic regions and compare to the average rates of loading. METHODS Force-time profiles were recorded using a hand force transducer placed between the hand of a doctor of chiropractic and the subjects back during 14 HVLA SM thrusts on asymptomatic volunteers while 3 doctors of chiropractic delivered the spinal manipulations. Doctors also delivered 36 posterior to anterior thoracic manipulations on a mannequin. Data were collected at a sampling rate of 1000 Hz using Motion Monitor software. Force-time profile data were differentiated to obtain instantaneous rates of loading. The data were reduced using a custom-written MathCad program and analyzed descriptively. RESULTS The instantaneous rates of loading were 1.7 to 1.8 times higher than average rates of loading, and instantaneous rates of unloading were 2.1 to 2.6 times the average rates of unloading during HVLA SMs. Maximum instantaneous rates of loading occurred 102 to 111 milliseconds prior to peak load. Maximum instantaneous rates of unloading occurred 121 to 154 milliseconds after the peak load. These data may be useful for further understanding of HVLA SMs. CONCLUSIONS The instantaneous rates of loading and where they occurred may be useful data for understanding and describing HVLA SMs.

Paraspinal Muscle Function Assessed with the Flexion-Relaxation Ratio at Baseline in a Population of Patients with Back-Related Leg Pain

OBJECTIVE The purpose of this study was to assess back muscle status at baseline in patients with back-related leg pain (BRLP) and to correlate those findings with baseline demographic and clinical factors. METHODS Surface electromyography (EMG) and electromagnetic motion-tracking detected flexion-relaxation response in 135 patients with BRLP. Surface EMG electrodes were attached with standard skin preparation over the right and left paraspinal muscles at L3. Participants moved from upright standing into full forward flexion, rested flexed for 1 second, and returned to the upright position. A flexion-relaxation ratio (FRR) factor was calculated as the root mean square EMG amplitude during forward flexion divided by the activity at full flexion. RESULTS High repeatability was found (intraclass correlation coefficient [ICC]([1,3]) = 0.94 and 0.86) between 3 cycles of assessment at the same session. Patients with BRLP exhibited low FRR values, indicating a loss of the flexion-relaxation response similar to that seen in low back pain patients. Patients with very low FRR had higher Roland-Morris Disability Questionnaire scores than the other patients, had increased incidence of straight leg raise test, and had decreased range and rate of forward flexion. CONCLUSIONS A subgroup of patients with BRLP was identified with very low FRR who exhibited more disability and clinical findings and decreased motion. The use of the inverted FRR factor, expressing muscle activity at the fully flexed and resting position as a percentage of peak activity during flexion, provides more stable numerical behavior and another perspective on interpreting FRRs.

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

BackgroundBack-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/DesignThis 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.DiscussionBack-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 RegistrationClinicalTrials.gov NCT00494065

Intradiscal Pressure Changes during Manual Cervical Distraction: A Cadaveric Study

The objective of this study was to measure intradiscal pressure (IDP) changes in the lower cervical spine during a manual cervical distraction (MCD) procedure. Incisions were made anteriorly, and pressure transducers were inserted into each nucleus at lower cervical discs. Four skilled doctors of chiropractic (DCs) performed MCD procedure on nine specimens in prone position with contacts at C5 or at C6 vertebrae with the headpiece in different positions. IDP changes, traction forces, and manually applied posterior-to-anterior forces were analyzed using descriptive statistics. IDP decreases were observed during MCD procedure at all lower cervical levels C4-C5, C5-C6, and C6-C7. The mean IDP decreases were as high as 168.7 KPa. Mean traction forces were as high as 119.2 N. Posterior-to-anterior forces applied during manual traction were as high as 82.6 N. Intraclinician reliability for IDP decrease was high for all four DCs. While two DCs had high intraclinician reliability for applied traction force, the other two DCs demonstrated only moderate reliability. IDP decreases were greatest during moving flexion and traction. They were progressevely less pronouced with neutral traction, fixed flexion and traction, and generalized traction.

Three-dimensional chiropractor-patient contact loads during side posture lumbar spinal manipulation: a pilot study

BackgroundPatients with low back pain often seek chiropractic care and more than ninety percent of Chiropractors use lumbar side posture manipulation for the treatment of low back pain. During this procedure chiropractors deliver forces by means of hand contact on the patient in a side lying position. The objective of this pilot study was to report on the three-dimensional forces at the hand contact between the chiropractor and the simulated patient (asymptomatic volunteers) during side posture lumbar high velocity low amplitude adjustments.MethodsIn 2005, two licensed chiropractors delivered spinal manipulations to the lumbar spines of the participants. A three-dimensional force transducer (Model # Mini-45, ATI-Industrial Automation, Apex, North Carolina) was used to measure the three-dimensional loads. The force-time histories were analyzed for preloads, peak loads, duration of thrusts to peak load, duration of thrust for completion, rate of loading, and magnitudes of the three forces and the resultant total force delivered by the chiropractor.ResultsThe two chiropractors delivered a total of 14 thrusts to the five asymptomatic volunteers. Normal force (Fz) is the dominating force, followed by inferior-superior force (Fx). The lateral force (Fy) occurred in both directions.ConclusionsThis study reports on the three dimensional load (three forces and the total resultant force) characteristics of chiropractor-patient hand contact while delivering a chiropractic high velocity low amplitude (HVLA) manipulation in a side lying position.

Training and certification of doctors of chiropractic in delivering manual cervical traction forces: Results of a longitudinal observational study.

Objective : Doctors of chiropractic (DCs) use manual cervical distraction to treat patients with neck pain. Previous research demonstrates variability in traction forces generated by different DCs. This article reports on a training protocol and monthly certification process using bioengineering technology to standardize cervical traction force delivery among clinicians. Methods : This longitudinal observational study evaluated a training and certification process for DCs who provided force-based manual cervical distraction during a randomized clinical trial. The DCs completed a 7-week initial training that included instructional lectures, observation, and guided practice by a clinical expert, followed by 3 hours of weekly practice sessions delivering the technique to asymptomatic volunteers who served as simulated patients. An instrument-modified table and computer software provided the DCs with real-time audible and visual feedback on the traction forces they generated and graphical displays of the magnitude of traction forces as a function of time immediately after the delivery of the treatment. The DCs completed monthly certifications on traction force delivery throughout the trial. Descriptive accounts of certification attempts are provided. Results : Two DCs achieved certification in traction force delivery over 10 consecutive months. No certification required more than 3 attempts at C5 and occiput contacts for 3 force ranges (0-20 N, 21-50 N, and 51-100 N). Conclusions : This study demonstrates the feasibility of a training protocol and certification process using bioengineering technology for training DCs to deliver manual cervical distraction within specified traction force ranges over a 10-month period.

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

BackgroundLow 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/DesignThis 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.DiscussionBeside 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 registrationNCT01670292 on clinicaltrials.gov.