Implementing A Flexible Sensor to Identify Forces during Instrument-Assisted Soft Tissue Mobilization

Round 1

Reviewer 1 Report

I enjoyed reading this manuscript as it was well structured. This is a very simple study but the results could be of interest to a broad spectrum of individuals

I have some minor comments

1. lines 44-55 you refer to force but use units of g - throughout i would use both g and N as units. 

2. The use of more than one clinician would have strengthened the output considerably

Author Response

Thank you for your review of our manuscript, we are glad that you found our simple technical report can have a broad impact on developing evidence for the efficacy of IASTM. Please see our responses to each of your comments below. We have listed the line numbers for any changes to the manuscript and highlighted them with a red typeface.

1. lines 44-55 you refer to force but use units of g - throughout i would use both g and N as units. 

Thank you for pointing this out. The reason that we had displayed grams in the discussion was because grams might be more relatable to clinicians due to the mass of the IASTM instruments often being reported in grams. As grams are a measure of mass and not force it would be inappropriate for us to report our data in both units (we have also corrected where we used grams in reference to force throughout the manuscript). To correct this potential point of confusion and to better aid clinicians in understanding the relationship of grams and newtons we have included a statement about how the mass of the instrument may be used as a proxy to judge how much force they are using.

Lines 290-293. While clinicians and researchers [13] may use the mass of instrument and the force of gravity to estimate the amount of force (e.g., 102g ≈ 1N); the force exerted by the instrument on the tissue depends not only on its mass but also on the acceleration of the stroke and the angle of application.

2. The use of more than one clinician would have strengthened the output considerably

Thank you for raising this valid point about the potential benefit of using multiple clinicians in the study. We did our best to use methods that would limit the potential for variation between clinicians. For example, had the clinician apply forces in a linear direction at the specified angles (through use of the goniometer), and rate/acceleration was accounted for by using a metronome. Additionally, having to maintain contact between the sensor and the skin simulant, and lifting between each stroke to accurately place the sensor on the simulant limited the potential for individual characteristics in how they may use IASTM in practice to influence the results. However, keeping the sensor in contact with patients, or a skin simulant may be an area where there is room for error and your point about generalizability is still valid. Future studies looking at clinical applications of the ELF should ideally involve multiple clinicians to ensure the results are widely applicable.

Reviewer 2 Report

Nice Work! However can be improved:

1) Abstract can be modified to clearly state the goal of the manuscript and what novelty does it carry.

2) Number of figures can be increased to give a better look.

3) Can discuss IASTM in greater detail, to enhance manuscript broad readability.

4) Figure 1 can be labelled.

5) A flow chart can be added to demonstrate the methods better.

6) Axes units missing in figure 2.

7) Since the manuscript involved using flexible sensor, it is strongly encouraged to cite some flexible sensor works:

(a)/10.1021/acsnano.2c12606

(b)10.1109/IUS46767.2020.9251458

(c)/10.1021/acsnano.3c11578

Author Response

Thank you for your thoughtful review of our manuscript. Please see our responses to each of your comments below. We have listed the line numbers for any changes to the manuscript and highlighted them with a red typeface.

1. Abstract can be modified to clearly state the goal of the manuscript and what novelty does it carry.

We agree that the abstract can be modified to state the goal of the manuscript more clearly and why it is novel. Also, we better introduced the IASTM technique per the reviewer’s 3^rd comment. Please see the revised abstract in the document.

2. Number of figures can be increased to give a better look.

We have added an additional figure displaying the calibration method in the software and the flow chart that was suggested. Another figure has also been added to the manuscript that presents how much of the resultant force from the force plate was contributed to by the vertical, horizontal, and anterior/posterior forces.

3. Can discuss IASTM in greater detail, to enhance manuscript broad readability.

Thank you for this feedback. An additional sentence has been added in the introduction where we introduce IASTM. We believe that this extra sentence is sufficient to enhance the broad readability of the introduction, as it provides a brief explanation of what IASTM is and who typically uses it. We do not wish to broaden the discussion on IASTM any further as this would detract from our focus on the potential importance of treatment forces.

Lines 29-31. IASTM treatments are commonly used by physical therapists, chiropractors, and other healthcare professionals to treat various musculoskeletal conditions (i.e., lateral epicondylitis, myofascial trigger points, hamstring strains)^2,3.

In the discussion we have also increased the breadth of discussion on IASTM to encompass different treatment strokes as well as the potential importance of the angle of the instrument during treatment.

4. Figure 1 can be labelled.

The flexible sensor has now been labelled on Figure 1.

5. A flow chart can be added to demonstrate the methods better.

A flow chart is now included in the manuscript as Figure 3.

6. Axes units missing in figure 2.

Thank you for noticing this. The axes are now labelled.

7. Since the manuscript involved using flexible sensor, it is strongly encouraged to cite some flexible sensor works:

Thank you for providing those references for flexible sensors. Although we did not find them directly relevant to our manuscript, they lead us to find scientific articles that addressed the ELF sensor, and other flexible sensors. We have now included more information on flexible sensors and the ELF.

Brimacombe et al. [38] found the ELF to have a root mean square error to be as low as 2.7% in static conditions where the sensor is not flexed. Moreover, commercially available flexible resistive pressure sensors have been found to be suitable for dynamic compression therapy applications [39]. Dynamic applications of the ELF have also been used to study forces on the curved surfaces of different laryngoscopes to compare in patient care [40].

Reviewer 3 Report

Please refer attached comments.

Comments for author File: Comments.pdf

Author Response

Thank you for your thoughtful review of our manuscript. Please see our responses to each of your comments below. We have listed the line numbers for any changes to the manuscript and highlighted them with a red typeface.

The title can be improved. Suggestion: Implementing A Flexible Sensor to Identify Forces During Instrument Assisted Soft Tissue Mobilization.

The abstract can be improved. For second sentence (line 10), However can be replaced by Moreover. Clear connection to the next sentence.

Thank you for this suggestion on the title, we found it to be a clearer description of the study and have made the change. We also had other reviewers comment on the abstract which has been fully revised.

The introduction provides a good overview of the importance of the study. A clear statement of what the aim to investigate and achieve in this work.

Thank you for your support of our study’s purpose and how we were able to get our points across.

The methodology can be improved. The mentioned methods used are three, but these methods are not clearly explained. Please explain the steps for BA, ICC and analysis on the correlation between BA & ICC. Does section 2.2 is BA? Data analysis on Section 2.3 is for ICC? Where is the section for analysis on the correlation between BA & ICC.

After reading your comment and reviewing our methods section we concluded that it needs to be restructured (we also included a flow chart). The poor structure of ideas may be why you are looking for a correlation between the BA analyses and the ICC. The correlation method was done separately from the BA and ICC statistical tests that evaluated discrete values for the peak and average forces. The linear model examined continuous data for the duration of a single stroke (from when the sensor was pressed into the skin simulant, until it was lifted off) at each of the four angles. Please note that we did not highlight the entire section in red that was reformatted, only where we added new information to elaborate on the BA plots (Lines 186-191)and ICC calculations (Lines178-183). 

The results are presented clearly but very brief. The discussion should elaborate on the implications of the findings and how they relate to the existing literature.

Thank you for raising these concerns. We agree that the results section is quite succinct; however, the information is robust enough to guide the discussion and is well supported by the figures and tables. The results have also been expanded to address a concern from another reviewer. We also further elaborated on the discussion to include points on difficulties with estimating forces and using patient pain thresholds for treatment forces (Lines 273-280, Lines 290-293), importance of different treatment angles (Lines 297-310), the importance of capturing different 3D treatment angles (Lines321-330), and other studies that have used the ELF outside of IASTM (Lines 331-337).

No conclusion found. The conclusion must summarize the key findings but could be more explicit in highlighting the practical applications or implications of the research. Consider discussing how the research could be used to improve the IATSM.

Your concerns about the conclusion are valid. The last paragraph has been modified to better summarize the document and provide take home messages for practical applications and future directions (Lines 372-383). This has also been categorized as the Conclusions under a heading.

Reviewer 4 Report

Currently, IASTM is becoming an increasingly popular method among medical professionals. Therefore, the topic of this article can be considered relevant. However, authors practically focus on only one aspect: whether the correct force is applied to the instrument during the procedure. From this point of view, the purpose of the article can be considered achieved.

However, there are many questions regarding what force should be considered optimal in terms of best soft tissue mobilization. The article does not discussed at all what the law of change of this force should be to achieve best results of therapy; it does not indicate what needs to be done in order to apply optimal force, etc.

In my opinion, this article can be recommended for publication if  authors provide, at a minimum, answers to the questions posed.

Author Response

Currently, IASTM is becoming an increasingly popular method among medical professionals. Therefore, the topic of this article can be considered relevant. However, authors practically focus on only one aspect: whether the correct force is applied to the instrument during the procedure. From this point of view, the purpose of the article can be considered achieved.

However, there are many questions regarding what force should be considered optimal in terms of best soft tissue mobilization. The article does not discussed at all what the law of change of this force should be to achieve best results of therapy; it does not indicate what needs to be done in order to apply optimal force, etc.

In my opinion, this article can be recommended for publication if  authors provide, at a minimum, answers to the questions posed.

The reviewer’s concerns about the importance of which forces are optimal for improving treatment outcomes are important. To the best of our knowledge there is no evidence comparing different forces on treatment outcomes. Our research aims to fill this gap in knowledge. This gap exists in large part because of the difficulties in quantifying treatment forces. We believe that the current study provides an obtainable solution for researchers and clinicians to begin documenting and reporting their treatment forces and the outcomes of those treatments. Our hypothesis would be that optimal forces will likely depend on the condition or goal of the treatment. For this reason, we provided discussion on studies that have separately looked at both high and low force treatments and provided commentary on how the findings from the current study can be used to improve on the prior methods (Lines 246-280). We have also expanded our discussion on the importance of treatment application angles (Lines 297-310), and different force vectors that could impact treatments (Lines 321-330). Additionally, we have made it clearer throughout the manuscript and that while some studies have reported forces through subjective mechanisms, the quantification of forces will be necessary to establish optimal forces and how they should be best applied.  

Reviewer 5 Report

This paper provides information about a notable gap in the field of manual therapy, particularly in quantifying the force applied during IASTM treatments. 

The study introduces a novel method to measure forces applied during IASTM using the Economical Load and Force (ELF) measurement system. This methodology as described in the draft allows for more objective and quantifiable measures of force application, a step forward in standardizing IASTM treatments and facilitating research in this area. The paper also includes comprehensive description of their methods, including calibration procedures, data analysis techniques, and the setup for measuring forces. 

The study reported decreased agreement between the ELF system and force plate measurements at a 30° treatment angle, indicating limitations in the ELF system's accuracy across all potential treatment angles. What about the IASTM treatments  that utilize lower angles, because the variability could affect the generalizability and applicability?

The proposed system is limited to quantifying force in only two dimensions, which restricts its utility in analyzing the complexity of IASTM treatments that may involve multi-directional force applications. This is quite common and expected in practical applications under various contexts. Understanding the nuances of shear versus vertical forces would be required for a comprehensive analysis of IASTM efficacy and technique optimization.

The reliance on a specific IASTM instrument with rounded edge beveling may limit the generalizability of findings to other commonly used IASTM tools, especially those with sharper edges that may not accommodate the ELF sensor as effectively.

Can the authors provide more information on translation of their findings to real world applications in clinical scenarios. Clinicians usually use

varied techniques and approachs and would adapt for patient-specific conditions which may not be fully captured by the standardized applications. 

Provide specific and additional details on the impact of 3D movements and forces inherent in manual therapy techniques. Add content about the future research that would warrant methods to capture these dynamics to more accurately reflect the complexity of IASTM treatments.

The manuscript does not fully discuss the limitations regarding treatment angles and the two-dimensional nature of force measurements is crucial, which would strengthen this paper. 

Author Response

Reviewer 5

Thank you for your thoughtful review of our manuscript. Please see our responses to each of your comments below. We have listed the line numbers for any changes to the manuscript and highlighted them with a red typeface.

The study reported decreased agreement between the ELF system and force plate measurements at a 30° treatment angle, indicating limitations in the ELF system's accuracy across all potential treatment angles. What about the IASTM treatments that utilize lower angles, because the variability could affect the generalizability and applicability?

We appreciate your consideration for the importance of the treatment angle of the instrument. To better address why different treatment angles could be important, we added a paragraph that includes a discussion on studies that have reported treatment angles and how the ELF could still be valid at treatment angles found to best increase tissue temperature (Lines 297-310).

The proposed system is limited to quantifying force in only two dimensions, which restricts its utility in analyzing the complexity of IASTM treatments that may involve multi-directional force applications. This is quite common and expected in practical applications under various contexts. Understanding the nuances of shear versus vertical forces would be required for a comprehensive analysis of IASTM efficacy and technique optimization.

We agree with your statement about the importance of 3D forces when it comes to assessing IASTM treatments and the limitations of pressure sensors for capturing the multi-planar nature of IASTM. To address this issue, we re-ran our analysis to account for whether the ELF was providing data relative to the resultant forces from the force plate in all three vectors (Lines 127-130). What we found was that the resultant forces were very close to the vertical forces. Thus, the ELF was still providing relevant data for what forces a patient might be experiencing when considering all force vectors. We followed up this analysis with some descriptive figures that demonstrate the contributions of each of the three force vectors to the overall resultant force (Figure 6) and to highlight that if the sensor can account for the vertical force, it accounts for more than 95% of the resultant force. At least during uniplanar treatment strokes. We mention this and add to the discussion that for multiplanar strokes, further analysis on the ELF is needed, and that triaxial sensors could better account for more nuanced treatments (Lines 321-333, Lines 356-358).

The reliance on a specific IASTM instrument with rounded edge beveling may limit the generalizability of findings to other commonly used IASTM tools, especially those with sharper edges that may not accommodate the ELF sensor as effectively.

Your point is well taken. We have better articulated this limitation in the discussion (Lines 343-345).

Can the authors provide more information on translation of their findings to real world applications in clinical scenarios. Clinicians usually use varied techniques and approachs and would adapt for patient-specific conditions which may not be fully captured by the standardized applications. 

Thank you for this feedback. We have added discussion on using patient pain thresholds for identifying treatment forces (Lines 273-280), how clinicians might use the weight of the instrument as a proxy for treatment forces (Lines 290-293), commentary on capturing forces from different strokes (Lines 321-333), and we also believe that the paragraph on different treatment angles (Lines 297-310) helps provide deeper clinical insights.

Provide specific and additional details on the impact of 3D movements and forces inherent in manual therapy techniques. Add content about the future research that would warrant methods to capture these dynamics to more accurately reflect the complexity of IASTM treatments.

Thank you for this comment. Investigating the importance of both shear and vertical forces will likely be necessary for advancement of this treatment. Understanding which strokes generate the most shear forces would be an interesting avenue to follow as well. This idea may be something we now investigate further thanks to your comment. We added to the discussion (Lines 359-365) to expand upon these concepts.

The manuscript does not fully discuss the limitations regarding treatment angles and the two-dimensional nature of force measurements is crucial, which would strengthen this paper. 

Thank you again for the feedback and how it will help guide our future direction. We believe the article is more robust and helpful for clinicians and researchers after addressing your concerns.