Force-Time Profile Characterization of the McTimoney Toggle-Torque-Recoil Technique

Measurement and Analysis of Biomechanical Outcomes of Chiropractic Adjustment Performance in Chiropractic Education and Practice

OBJECTIVE

The purpose of this study was to compare biomechanical measures of chiropractic adjustment performance of the McTimoney toggle-torque-recoil (MTTR) technique among students and chiropractors.

METHODS

Fifty-three participants (15 year-3 [Y3] and 16 year-5 chiropractic students and 22 McTimoney chiropractors [DCs]) participated in this study. Each applied 10 MTTR thrusts to a dynamic load cell, 5 each with their left and right hands. Biomechanical variables including preload force, peak force, time to peak force, thrust duration, and total thrust time were computed from each of the force-time histories and compared within groups using a series of 2-way analysis of variance to evaluate the effects of sex and handedness, and between groups to determine the effect of experience using a series of 3-way analysis of variance. The Games-Howell post hoc test was used to further assess pairwise comparisons.

RESULTS

Mean time to peak force was more than 3 × shorter for DCs (69.96 ms) compared with Y3 students (230.36 ms) (P = .030). Likewise, mean thrust duration was also found to be nearly 2.5-fold significantly shorter for DCs (117.77 ms) compared with Y3 students (283.84 ms) (P = .030). The DCs took significantly less total thrust time (mean = 1.27 seconds) in administering MTTR thrusts than Y3 students (1.89 seconds) (P = .006). No significant differences were found among any of the 3 clinician groups for peak force or in time to peak force or thrust duration for comparisons of all 10 MTTR thrusts among year-5 students and DCs. Higher peak forces were observed for thrusts delivered with clinicians' dominant hands (P = .001), and the fastest thrusts were found for the dominant hands of DCs (P = .001). Sex had no significant effect on biomechanical variables. The Y3 students had significant greater variability in thrust times for each hand and for analyses of both hands combined (P = .001).

CONCLUSION

Training and experience were found to result in shorter MTTR thrust times and other biomechanical variables that have been identified as important factors in the mechanisms of chiropractic adjustments. Identification of such biomechanical markers as performance outcomes may be of assistance in providing feedback for training in chiropractic education and technique application.

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 subject's 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.

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

Background

Patients 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.

Methods

In 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.

Results

The 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.

Conclusions

This 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.

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.

Optimized prediction of contact force application during side-lying lumbar manipulation

OBJECTIVES

The purposes of this study included the following: (1) to predict L3 contact force during side-lying lumbar manipulation by combining direct and indirect measurements into a single mathematical framework and (2) to assess the accuracy and confidence of predicting L3 contact force using common least squares (CLS) and weighted least squares (WLS) methods.

METHODS

Five participants with no history of lumbar pain underwent 10 high-velocity, low-amplitude lumbar spinal manipulations at L3 in a side-lying position. Data from 5 low-force criterion standard trials where the L3 contact force was directly measured were used to generate participant-specific force prediction algorithms. These algorithms were used to predict L3 contact force in 5 experimental trials performed at therapeutic levels. The accuracy and effectiveness of CLS and WLS methods were compared.

RESULTS

Differences between the CLS-predicted forces and the criterion standard-measured forces were 621.0 ± 193.5 N. Differences between the WLS-predicted forces and the criterion standard-measured forces were -3.6 ± 9.1 N. The 95% limits of agreement ranged from 234.0 to 1008.0 N for the CLS and -21.9 to 14.7 N for the WLS. During both the criterion standard and experimental trials, the CLS overestimated contact forces with larger variance than the WLS.

CONCLUSION

This novel method to predict spinal contact force combines direct and indirect measurements into a single framework and preserves clinically relevant practitioner-participant contacts. As advanced instrumentation becomes available, this framework will enable advancements in training and high-quality research on mechanisms of spinal manipulative therapy.

Manipulative therapies for infantile colic

BACKGROUND

Infantile colic is a common disorder, affecting around one in six families, and in 2001 was reported to cost the UK National Health Service in excess of £65 million per year (Morris 2001). Although it usually remits by six months of age, there is some evidence of longer-term sequelae for both children and parents.Manipulative therapies, such as chiropractic and osteopathy, have been suggested as interventions to reduce the severity of symptoms.

OBJECTIVES

To evaluate the results of studies designed to address efficacy or effectiveness of manipulative therapies (specifically, chiropractic, osteopathy and cranial manipulation) for infantile colic in infants less than six months of age.

SEARCH METHODS

We searched following databases: CENTRAL (2012, Issue 4), MEDLINE (1948 to April Week 3 2012), EMBASE (1980 to 2012 Week 17), CINAHL (1938 to April 2012), PsycINFO (1806 to April 2012), Science Citation Index (1970 to April 2012), Social Science Citation Index (1970 to April 2012), Conference Proceedings Citation Index - Science (1990 to April 2012) and Conference Proceedings Citation Index - Social Science & Humanities (1970 to April 2012). We also searched all available years of LILACS, PEDro, ZETOC, WorldCat, TROVE, DART-Europe, ClinicalTrials.gov and ICTRP (May 2012), and contacted over 90 chiropractic and osteopathic institutions around the world. In addition, we searched CentreWatch, NRR Archive and UKCRN in December 2010.

SELECTION CRITERIA

Randomised trials evaluating the effect of chiropractic, osteopathy or cranial osteopathy alone or in conjunction with other interventions for the treatment of infantile colic.

DATA COLLECTION AND ANALYSIS

In pairs, five of the review authors (a) assessed the eligibility of studies against the inclusion criteria, (b) extracted data from the included studies and (c) assessed the risk of bias for all included studies. Each article or study was assessed independently by two review authors. One review author entered the data into Review Manager software and the team's statistician (PP) reviewed the chosen analytical settings.

MAIN RESULTS

We identified six studies for inclusion in our review, representing a total of 325 infants. There were three further studies that we could not find information about and we identified three other ongoing studies. Of the six included studies, five were suggestive of a beneficial effect and one found no evidence that manipulative therapies had any beneficial effect on the natural course of infantile colic. Tests for heterogeneity imply that there may be some underlying difference between this study and the other five.Five studies measured daily hours of crying and these data were combined, suggesting that manipulative therapies had a significant effect on infant colic - reducing average crying time by one hour and 12 minutes per day (mean difference (MD) -1.20; 95% confidence interval (CI) -1.89 to -0.51). This conclusion is sustained even when considering only studies with a low risk of selection bias (sequence generation and allocation concealment) (MD -1.24; 95% CI -2.16 to -0.33); those with a low risk of attrition bias (MD -1.95; 95% CI -2.96 to -0.94), or only those studies that have been published in the peer-reviewed literature (MD -1.01; 95% CI -1.78 to -0.24). However, when combining only those studies with a low risk of performance bias (parental 'blinding'), the improvement in daily crying hours was not statistically significant (MD -0.57; 95% CI -2.24 to 1.09).One study considered whether the reduction in crying time was clinically significant. This found that a greater proportion of parents of infants receiving a manipulative therapy reported clinically significant improvements than did parents of those receiving no treatment (reduction in crying to less than two hours: odds ratio (OR) 6.33; 95% CI 1.54 to 26.00; more than 30% reduction in crying: OR 3.70; 95% CI 1.15 to 11.86).Analysis of data from three studies that measured 'full recovery' from colic as reported by parents found that manipulative therapies did not result in significantly higher proportions of parents reporting recovery (OR 11.12; 95% CI 0.46 to 267.52).One study measured infant sleeping time and found manipulative therapy resulted in statistically significant improvement (MD 1.17; 95% CI 0.22 to 2.12).The quality of the studies was variable. There was a generally low risk of selection bias but only two of the six studies were evaluated as being at low risk of performance bias, three at low risk of detection bias and one at low risk of attrition bias.One of the studies recorded adverse events and none were encountered. However, with only a sample of 325 infants, we have too few data to reach any definitive conclusions about safety.

AUTHORS' CONCLUSIONS

The studies included in this meta-analysis were generally small and methodologically prone to bias, which makes it impossible to arrive at a definitive conclusion about the effectiveness of manipulative therapies for infantile colic.The majority of the included trials appeared to indicate that the parents of infants receiving manipulative therapies reported fewer hours crying per day than parents whose infants did not, based on contemporaneous crying diaries, and this difference was statistically significant. The trials also indicate that a greater proportion of those parents reported improvements that were clinically significant. However, most studies had a high risk of performance bias due to the fact that the assessors (parents) were not blind to who had received the intervention. When combining only those trials with a low risk of such performance bias, the results did not reach statistical significance. Further research is required where those assessing the treatment outcomes do not know whether or not the infant has received a manipulative therapy.There are inadequate data to reach any definitive conclusions about the safety of these interventions.