Changes in Manipulative Peak Force Modulation and Time to Peak Thrust among First-Year Chiropractic Students Following a 12-Week Detraining Period

Development of a basic evaluation model for manual therapy learning in rehabilitation students based on the Delphi method

OBJECTIVE

Manual therapy is a crucial component in rehabilitation education, yet there is a lack of models for evaluating learning in this area. This study aims to develop a foundational evaluation model for manual therapy learning among rehabilitation students, based on the Delphi method, and to analyze the theoretical basis and practical significance of this model.

METHODS

An initial framework for evaluating the fundamentals of manual therapy learning was constructed through a literature review and theoretical analysis. Using the Delphi method, consultations were conducted with young experts in the field of rehabilitation from January 2024 to March 2024. Fifteen experts completed three rounds of consultation. Each round involved analysis using Dview software, refining and adjusting indicators based on expert opinions, and finally summarizing all retained indicators using Mindmaster.

RESULTS

The effective response rates for the three rounds of questionnaires were 88%, 100%, and 100%, respectively. Expert familiarity scores were 0.91, 0.95, and 0.95; coefficient of judgment were 0.92, 0.93, and 0.93; authority coefficients were 0.92, 0.94, and 0.94, respectively. Based on three rounds of consultation, the model established includes 3 primary indicators, 10 secondary indicators, 17 tertiary indicators, and 9 quaternary indicators. A total of 24 statistical indicators were finalized, with 8 under the Cognitive Abilities category, 10 under the Practical Skills category, and 6 under the Emotional Competence category.

CONCLUSION

This study has developed an evaluation model for manual therapy learning among rehabilitation students, based on the Delphi method. The model includes multi-level evaluation indicators covering the key dimensions of Cognitive Abilities, Practical Skills, and Emotional Competence. These indicators provide a preliminary evaluation framework for manual therapy education and a theoretical basis for future research.

Developing spinal manipulation psychomotor skills competency: A systematic review of teaching methods

OBJECTIVE

To update the state of the art regarding the acquisition of spinal high-velocity low-amplitude psychomotor skills competency among chiropractors and chiropractic students.

METHODS

Available electronic articles from 5 databases, published between June 2015 and August 2020, were obtained. Eligible studies underwent methodological quality assessments using the Joanna Briggs Institute Critical Appraisal Checklists and Cochrane Collaboration's Risk of Bias Tools.

RESULTS

Fourteen critically appraised studies were identified, including 10 cohort studies and 4 randomized controlled trials. There was no literature excluded due to high risk of bias. The type of augmented devices included a mannequin on a force platform, a computer-connected device, a human analogue mannequin, and a 3-dimensional electrogoniometer with an instrumented spatial linkage.

CONCLUSION

The use of augmented feedback devices such as human analogue mannequins with force-sensing table technology and computer-connected devices is potentially beneficial in the chiropractic curricula and may facilitate student learning and improvement of spinal manipulation. More studies are required to determine whether psychomotor skill aids translate directly into raised competency levels in novice clinicians.

Can self-assessment and augmented feedback improve performance and learning retention in manual therapy: results from an experimental study

BACKGROUND

The purpose of this study was to investigate how feedback and self-assessment strategies affect performance and retention of manual skills in a group of chiropractic students.

METHODS

Seventy-five students participated in two spinal manipulation (SM) learning sessions using a force-sensing table. They were recruited between May and November 2022 during HVLA technical courses. Students were randomly assigned into three different groups: participants in group 1 received visual feedback, those in group 2 received visual feedback after self-assessment, and participants in group 3 (C) received no feedback. During the first session, participants started with one block of 3 familiarization trials, followed by two blocks of 6 SM HVLA (high velocity low amplitude) posterior-to-anterior thoracic SM trials, with 3 trials performed with a target force of 450 N and 3 others at 800 N. They received feedback according to their group during the first block, but no feedback was provided during the second block. All participants were invited to participate in a second session for the retention test and to perform a new set SM without any form of feedback.

RESULTS

Results showed that visual feedback and visual feedback in addition to self-assessment did not improve short-term SM performance, nor did it improve performance at the one-week retention test. The group that received visual feedback and submitted to self-assessment increased the difference between the target force and the peak force applied, which can be considered a decrease in performance.

CONCLUSION

No learning effects between the three groups of students exposed to different feedback and self-assessment learning strategies were highlighted in the present study. However, future research on innovative motor learning strategies could explore the role of external focus of attention, self-motivation and autonomy in SM performance training.

Development of a mannequin lab for clinical training in a chiropractic program

OBJECTIVE

Faced with COVID-19 safety protocols that severely limited the ability to conduct chiropractic technique instruction in the usual manner, our university invested the resources to develop a new mannequin lab for hands-on training, which would help supplement the loss of person-to-person contact.

METHODS

Training mannequins could enable student learning of palpation and adjustment skills while avoiding close human-human contact. The university had developed a mannequin over the previous 4 years consisting of a full-sized human torso with individually movable and palpable vertebrae, pelvis, and thighs. In the mannequin, 64 pressure sensors are attached to particular vertebral and skeletal landmarks and provide feedback on palpation location and level of force applied. We assembled 3 teams to produce 20 copies of that mannequin for student use.

RESULTS

Mannequins were produced in 7 weeks, and space was built out for a special lab. Faculty members are developing classroom procedures to introduce the mannequin to students, phase in the skills from static and motion palpation, and practice thrust performance.

CONCLUSION

The production run was successful, and the resulting equipment, well-received by students and faculty. In addition to helping teach manual skills, the lab serves as a platform for educational research to test the efficacy of mannequin-based training protocols. With the pressure sensors on known locations along the spine, future research may be able to test the ability of students to identify and contact specific target locations for adjustive thrusts.

Differing Characteristics of Human-Shaped Visual Stimuli Affect Clinicians' Dosage of a Spinal Manipulative Thrust on a Low-Fidelity Model: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to determine whether chiropractic clinicians modulate spinal manipulation (SM) thrust characteristics based on visual perception of simulated human silhouette attributes.

METHODS

We performed a cross-sectional within-participant design with 8 experienced chiropractors. During each trial, participants observed a human-shaped life-sized silhouette of a mock patient and delivered an SM thrust on a low-fidelity thoracic spine model based on their visual perception. Silhouettes varied on the following 3 factors: apparent sex (male or female silhouette), height (short, average, tall), and body mass index (BMI) (underweight, healthy, obese). Each combination was presented 6 times for a total of 108 trials in random order. Outcome measures included peak thrust force, thrust duration, peak preload force, peak acceleration, time to peak acceleration, and rate of force application. A 3-way repeated measures analysis of variance model was used to for each variable, followed by Tukey's honestly significant difference on significant interactions.

RESULTS

Peak thrust force was reduced when apparent sex of the presented silhouette was female (F_1,7 = 5.70, P = .048). Thrust duration was largely invariant, except that a BMI by height interaction revealed a longer duration occurred for healthy tall participants than healthy short participants (F_4,28 = 4.34, P = .007). Compared to an image depicting obese BMI, an image appearing underweight lead to reduced peak acceleration (F_2,5 = 6.756, P = .009). Clinician time to peak acceleration was reduced in short compared to tall silhouettes (t₇ = 2.20, P = .032).

CONCLUSION

Visual perception of simulated human silhouette attributes, including apparent sex, height, and BMI, influenced SM dose characteristics through both kinetic and kinematic measures. The results suggest that visual information from mock patients affects the decision-making of chiropractic clinicians delivering SM thrusts.

Effects of Distinct Force Magnitude of Spinal Manipulative Therapy on Blood Biomarkers of Inflammation: A Proof of Principle Study in Healthy Young Adults

OBJECTIVES

The purpose of this preliminary study was to determine the influence of thoracic spinal manipulation therapy (SMT) of different force magnitudes on blood biomarkers of inflammation in healthy adults.

METHODS

Nineteen healthy young adults (10 female, age: 25.6 ± 1.2 years) were randomized into the following 3 groups: (1) control (preload only), (2) single thoracic SMT with a total peak force of 400N, and (3) single thoracic SMT with a total peak force of 800N. SMT was performed by an experienced chiropractor, and a force-plate embedded treatment table (Force Sensing Table Technology) was used to determine the SMT force magnitudes applied. Blood samples were collected at pre intervention (baseline), immediately post intervention, and 20 minutes post intervention. A laboratory panel of 14 different inflammatory biomarkers (pro, anti, dual role, chemokine, and growth factor) was assessed by multiplex array. Change scores from baseline of each biomarker was used for statistical analysis. Two-way repeated-measures analysis of variance was used to investigate the interaction and main effects of intervention and time on cytokines, followed by Tukey's multiple comparison test (P ≤ .05).

RESULTS

A between-group (800N vs 400N) difference was observed on interferon-gamma, interleukin (IL)-5, and IL-6, while a within-group difference (800N: immediately vs 20 minutes post-intervention) was observed on IL-6 only.

CONCLUSION

In this study, we measured short-term changes in plasma cytokines in healthy young adults and found that select plasma pro-inflammatory and dual-role cytokines were elevated by higher compared to lower SMT force. Our findings aid to advance our understanding of the potential relationship between SMT force magnitude and blood cytokines and provide a healthy baseline group with which to compare similar studies in clinical populations in the future.

Devices Used to Measure Force-Time Characteristics of Spinal Manipulations and Mobilizations: A Mixed-Methods Scoping Review on Metrologic Properties and Factors Influencing Use

Background: Spinal manipulations (SMT) and mobilizations (MOB) are interventions commonly performed by many health care providers to manage musculoskeletal conditions. The clinical effects of these interventions are believed to be, at least in part, associated with their force-time characteristics. Numerous devices have been developed to measure the force-time characteristics of these modalities. The use of a device may be facilitated or limited by different factors such as its metrologic properties.

Objectives: This mixed-method scoping review aimed to characterize the metrologic properties of devices used to measure SMT/MOB force-time characteristics and to determine which factors may facilitate or limit the use of such devices within the context of research, education and clinical practice.

Methods: This study followed the Joanna Briggs Institute's framework. The literature search strategy included four concepts: (1) devices, (2) measurement of SMT or MOB force-time characteristics on humans, (3) factors facilitating or limiting the use of devices, and (4) metrologic properties. Two reviewers independently reviewed titles, abstracts and full articles to determine inclusion. To be included, studies had to report on a device metrologic property (e.g., reliability, accuracy) and/or discuss factors that may facilitate or limit the use of the device within the context of research, education or clinical practice. Metrologic properties were extracted per device. Limiting and facilitating factors were extracted and themes were identified.

Results: From the 8,998 studies initially retrieved, 46 studies were finally included. Ten devices measuring SMT/MOB force-time characteristics at the clinician-patient interface and six measuring them at patient-table interfaces were identified. Between zero and eight metrologic properties were reported per device: measurement error (defined as validity, accuracy, fidelity, or calibration), reliability/repeatability, coupling/crosstalk effect, linearity/correlation, sensitivity, variability, drift, and calibration. From the results, five themes related to the facilitating and limiting factors were developed: user-friendliness and versatility, metrologic/intrinsic properties, cost and durability, technique application, and feedback.

Conclusion: Various devices are available to measure SMT/MOB force-time characteristics. Metrologic properties were reported for most devices, but terminology standardization is lacking. The usefulness of a device in a particular context should be determined considering the metrologic properties as well as other potential facilitating and limiting factors.

Mechanical properties of a thoracic spine mannequin with variable stiffness control

OBJECTIVE

To test the posterior-to-anterior stiffness (PAS) of a new thoracic spine training simulator under different conditions of "fixation."

METHODS

We constructed a thoracic spine model using plastic bones and ribs mounted in a wooden box, with skin and soft tissue simulated by layers of silicone and foam. The spine segment could be stiffened with tension applied to cords running through the vertebrae and ribs. We tested PAS at 2 tension levels using a custom-built device to apply repetitive loads at the T6 spinous process (SP) and over adjacent soft tissue (TP) while measuring load and displacement. Stiffness was the slope of the force-displacement curve from 55 to 75 N.

RESULTS

Stiffness in the unconstrained (zero tension) condition over the SP averaged 11.98 N/mm and 6.72 N/mm over the TP. With tension applied, SP stiffness increased to 14.56 N/mm, and TP decreased to 6.15 N/mm.

CONCLUSION

Thoracic model compliance was similar to that reported for humans. The tension control system increased stiffness by 21.3% only over the SP. Stiffness over the TP was dominated by the lower stiffness of the thicker foam layer and did not change. The mannequin with these properties may be suitable for use in manual training of adjusting or PAS testing skills.

Characteristics of Forces at the Clinician–Patient and Patient–Table Interfaces During Thoracic Spinal Manipulation in Asymptomatic Adults Are Consistent With Deformable Body Models

Investigating all forces exerted on the patient’s body during high-velocity, low-amplitude spinal manipulative therapy (SMT) remains fundamental to elucidate how these may contribute to SMT’s effects. Previous conflicting findings preclude our understanding of the relationship between SMT forces acting at the clinician–patient and patient–table interfaces. This study aimed to quantify forces at the clinician–participant and participant–table interfaces during thoracic SMT in asymptnomatic adults. An experienced clinician provided a posterior to anterior SMT centered to T7 transverse processes using predetermined force–time characteristics to 40 asymptomatic volunteers (20 females; average age = 27.2 [4.9] y). Forces at the clinician–participant interface were recorded by triaxial load cells; whereas, forces at the participant–table interface were recorded by the force-sensing table technology. Preload force, total peak force, time to peak, and loading rate at each interface were analyzed descriptively. Total peak vertical forces at the clinician–participant interface averaged 532 (71) N while total peak forces at the participant–table interface averaged 658 (33) N. Forces at the participant–table interface were, on average, 1.27 (0.25) times larger than the ones at the clinician–participant interface. Larger forces at the participant–table interface compared with the ones at the clinician–participant interface during thoracic SMT are consistent with mathematical models developed to investigate thoracic impact simulating a dynamic force-deflection response.

Investigation of reaction force magnitude and orientation during supine thoracic thrust manipulation applied to intervertebral and costovertebral regions

BACKGROUND

Spinal manipulative techniques are commonly used in manual therapies but quantified descriptive and reliability data are lacking considering supine thoracic thrust manipulation.

OBJECTIVES

The purpose of this study is to explore and compare kinetic parameters during supine thoracic thrust manipulation performed at two different thoracic regions. Intra-rater task repeatability and influence of practitioners were estimated.

DESIGN

Exploratory and agreement study.

METHODS

Kinetic parameters were assessed by examining reaction force magnitude and orientation (on the basis of the zenithal angle) using force platforms. Manipulative procedure (consisting in the application of 3 preloads followed by one thrust adjustment) at both intervertebral and costovertebral region was performed by different practitioners at three sessions. Application of thrust was allowed for experienced practitioners only. Preload force, peak force magnitude and vector force orientation were compared between anatomical sites, sessions and practitioners, and bias with limit of agreement were estimated.

RESULTS

Repeatability analysis showed that practitioners achieved similar preload and peak force independent of the session, with comparable force orientation. Differences between practitioners were observed for preload and peak force but not regarding the zenithal angle during the thrust phase.

CONCLUSIONS

The present study is the first that explores kinetic parameters for supine thoracic thrust manipulation applied on two different regions of the thorax. Results confirm consistency of performance among practitioners for supine manipulative techniques at intervertebral and costovertebral region. While task repeatability was confirmed, several differences were observed between practitioners. Further investigations would examine velocity, acceleration and potential neurophysiological effect of such manipulative technique.

Effects of an 8-week physical exercise program on spinal manipulation biomechanical parameters in a group of 1st-year chiropractic students

OBJECTIVE

To determine the effects of a physical exercise program on spinal manipulation (SM) performance in 1st-year chiropractic students.

METHODS

One hundred and thirteen students from 2 chiropractic schools were assigned to 1 of 2 groups: exercise group (EG) for campus A students or control group (CG) (no training) for campus B students. All participated in 2 1-hour experimental training sessions that were added to the usual technique curriculum. At the beginning and at the end of each session, SM thrust duration and preload force release were recorded as dependent variables in 5 trials performed on a force-sensing table for a total of 10 recorded trials per session. The session consisted of several drills during which augmented feedback was provided to students to improve their skills. The EG performed physical exercises (push-ups, core stabilization, and speeder board exercises) 3 times per week for an 8-week period between the 2 training sessions.

RESULTS

The mean thrust duration increased between the 2 sessions [+0.8 ms (±15.6)]. No difference between groups was found using a t test for independent samples (p = .94). The mean preload force release decreased between the 2 sessions (-6.1 N [±17.1]). Differences between groups were found using a t test for independent samples (p = .03); the results showed a reduction of preload force release in the participants in the EG group compared to those in the CG group (-8.1 N [±16.9] vs -0.3 N [±16.5]).

CONCLUSION

A physical exercise program seems to be beneficial in the SM learning process; chiropractic students should therefore be encouraged to do home physical exercises to develop their physical capabilities and improve SM delivery.

Spinal manipulation frequency and dosage effects on clinical and physiological outcomes: a scoping review

Introduction

The burden of musculoskeletal disorders increases every year, with low back and neck pain being the most frequently reported conditions for seeking manual therapy treatment. In recent years, manual therapy research has begun exploring the dose-response relationship between spinal manipulation treatment characteristics and both clinical and physiological response to treatment.

Objective

The purpose of this scoping review was to identify and appraise the current state of scientific knowledge regarding the effects of spinal manipulation frequency and dosage on both clinical and physiological responses.

Methods

A scoping review was conducted to identify all available studies pertaining to our research question. Retrieved papers were screened using a 2-phase method, a selective sorting with titles and abstracts. Potentially relevant studies were read, and data was extracted for all included studies. Randomized control trials were assessed using the Cochrane Risk of Bias Tool for quality assessment.

Results

The search yielded 4854 publications from which 32 were included for analysis. Results were sorted by dosage or frequency outcomes, and divided into human or animal studies. Animal studies mainly focused on dosage and evaluated physiological outcomes only. Studies investigating spinal manipulation dosage effects involved both human and animal research, and showed that varying thrust forces, or thrust durations can impact vertebral displacement, muscular response amplitude or muscle spindle activity. Risk of bias analysis indicated only two clinical trials assessing frequency effects presented a low risk of bias. Although trends in improvement were observed and indicated that increasing the number of SM visits in a short period of time (few weeks) decreased pain and improve disability, the differences between the studied treatment frequencies, were often not statistically significant and therefore not clinically meaningful.

Conclusion

The results of this study showed that SM dosage and frequency effects have been mostly studied over the past two decades. Definitions for these two concepts however differ across studies. Overall, the results showed that treatment frequency does not significantly affect clinical outcomes during and following a SM treatment period. Dosage effects clearly influence short-term physiological responses to SM treatment, but relationships between these responses and clinical outcomes remains to be investigated.

Learning spinal manipulation: Gender and expertise differences in biomechanical parameters, accuracy, and variability

OBJECTIVE:

The purpose of this study was to investigate gender differences and expertise effects on biomechanical parameters as well as force accuracy and variability for students learning spinal manipulation.

METHODS:

A total of 137 fourth- and fifth-year students were recruited for the study. Biomechanical parameters (preload, time to peak force, peak force, rate of force), as well as accuracy and variability of thoracic spine manipulation performance, were evaluated during 5 consecutive trials using a force-sensing table and a target force of 450 N. Gender, expertise differences on biomechanical parameters, as well as constant, variable, and absolute error were assessed using 2-way analysis of variance.

RESULTS:

Analyses showed significant gender differences for several biomechanical parameters, as well as significant gender differences in accuracy and variability. Although women showed lower time to peak force and rate of force values, they were more precise and showed less variability than men when performing thoracic spine manipulations. Students with clinical expertise (fifth-year students) used less force and were more precise.

CONCLUSION:

Our results showed that gender differences in spinal manipulation performance exist and that these differences seem to be mainly explained by alternative motor strategies. To develop gender-specific teaching methods, future studies should explore why men and women approach spinal manipulation tasks differently.