Effects of Toe-Out and Toe-In Gaits on Lower-Extremity Kinematics, Dynamics, and Electromyography

Round 1

Reviewer 1 Report

This is an interesting paper. However, please consider the following points:

Abstract – any  statistical values to report?

Line 44 – what is meant by implementation level?

Line 46 – what is meant by difficultly in maintenance?

Line 46 – please provide clarity regarding what is meant by ‘Previous work reported that peak value

KAM is positively related to walking speed, however, whilst peak KAM reduces with decreasing walking speed, the load duration increases the effect of gait modifications on the neuro-muscular function is less [14, 15].’ In particular, I am unsure what is meant regarding the load duration increasing the effect of gait modifications – do you mean the foot placement?

Line 52 -  Individualized toe-in and toe-out would lead to immediate quadriceps and hamstrings co-contraction increases in healthy adults [11] – please indicate the importance of this?

Line 63 – what do the first and second peaks represent?

Line 96 – please provide specific detail on the location of the markers

Line 99 – which muscles? What guidelines were followed to ensure that these were appropriately positioned? (http://seniam.org/)?

How were the force plate data used in the inverse dynamics calculation? did they interpolated or extrapolate the GRF or kinematic data

Line 107 – how did this pace compare to typical walking speed for these individuals? Why was this speed selected?

Line 112 -  ‘Detailed information on the markers and the surface EMG locations are shown in Figure 2a.‘ if this were earlier it would contribute to clarifying my earlier point

Line 115 – mentions a hypothesis but this is not given in the introduction

-  Why were 90 degrees and 50 degrees used for toe in and out? What degree of foot placement equaled natural? What was the within group standard deviation?

-   Why is there no statistical analysis? Whilst qualitatively similar trends may have been shown were these significant? This significantly impacts the interpretation of the results and the detail of the discussion. Did all shown these trends? Was there a specific feature of interest that could be compared such as a peak or could the average value be used?

Table 1: please provide full names of the muscle – table should be understandable without reading the text

-   What was the impact of the walking speed on results and how did the narrow population impact results, beyond just suggesting that it may be important

-  please discuss the impact of the use of a female on the results. For instance, how does the wider hips typical with females impact the results?

 - please make it clearer throughout what this paper is adding to the literature on this topic and how it is filling gaps that prevent the treatment of individuals

 - In the methods please specify how the change in foot position was bought about and how it was controlled.

- please specify how the results can be used in the future.

- please comment on whether this study could be extended to a larger group of different walking gaits for statistical analysis

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The article has been divided into the chapters and subchapters correctly. The authors cited 43 references. The research tools and the method of results analysis were selected correctly. The article takes up a very interesting and important issues. The reviewed paper contains a several publishing errors described in the specific comments. After making the necessary corrections the paper can be accepted for publishing.

Specific comments:

in the chapter „Methods” list the muscles on which the electrodes have been sticked; chapters 3.3 & 3.5 should start with a text, not a table; table 1 contains abbreviations of muscle names, they should be explained in the text or in the table to make them homogeneous with Figure 5; the chapter "Conclusion" should be separate, not included into the chapter "Discussion"; in the lines 289 & 291 authors use the word "significant" which is not a suitable in the case of a small research group and missing statistical analysis. I suggest to change it to more gently.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors, thank you for clarifying a number of my questions. However, I do have further comments to make, particularly in relation to the reporting of the findings. 

1) The abstract I am not sure that the results indicate the ability of KAM as surrogate measures - this needs more explanation in the discussion as does the suggestion it is more reliable as reliability was not measured. Surrogate measures are also mentioned throughout. Please provide detail on what you mean and why they are important. Do you mean an external and indirect measurement of load occurring within the joint? If so how do you know that they are measuring the same thing? More detail behind the links between the measures are needed. 

2) When describing the graph data please highlight that this interpretation is qualitative 

3) line 205 - 'were not significant'

4) highlight in text that the ML force was significant

5) EMG data - why is this no presented like the rest of the data? This needs rewriting to reflect any statistical analysis performed. Why are the individual data of interest? Are you suggesting an individualised response? If so report the group effect (or lack of it) and refer to the individualised response in discussion. Alternatively, better justification for exploring this specifically needs to be made in the introduction and in the aims of the study.On line 214 it refers to significant differences and trends but I dont see evidence of the significance (statistically) do you mean there are qualitative differences and trends?

6) check the tables for inaccuracies. In some instances data are highlighted as having post-hoc analysis (1st hip adduction for example) without the main effect being significant (i.e. 0.12). Similarly peak plantar flexion is significant without post hoc analysis being reported. This is particularly the case for table 4.

7) results could be more thoroughly reported (search the internet for reporting ANOVA results in text)

8) line 252 - no evidence of EMG alterations reported

9) line 258 - should be slight effects and also there is no evidence of this except for ml force. Please can an explanation be given for this.

10) if the discussion is to make generalisations based on trends rather than stats then this needs to be clear. Similarly why were the trends not statistically significant?

11) the discussion needs organising into paragraphs to aid the ability of the reader to follow

12) the use of the results (i.e. by the physio) should come after the limitations 

13) line 297 - if the accuracy is not very high why was it used and how can the results be confidently interpreted

14) Rewrite the conclusion to reflect that some of the data changed but others did not. Presently there is a suggestion that all angles and EMG changed. The conclusion should also be concise and address just the aims and hypotheses. With that in mind there needs hypotheses in the introduction.

15) please add to the methods whether the study was approved via an ethics committee or process?

 

Author Response

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Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

Thank you for your considered responses. I would like the following very minor issues addressed 

1) please detail whether the study was approved by an external group of individuals at your university for ethical considerations 

2) in the results, it mentions significant in trend and difference. This does not appear to be the case as no statistics are reported. It appears that due to individual differences statistical analysis could not be performed - was this the case, if so please add to the methods and amend the results accordingly

3)In the discussion please explain what the EMG data adds to the interpretation of the movement data

4) please rephrase throughout the use of the term range of motion - this refers to the range movement in different directions which is related but not the same as the data you have measured which is peak value in one direction. This could be assumed to increase the range of motion but may not. This interpretation could be included in the discussion. 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Very interesting topic.

Some critical literature is missng (e.g. Chang, A., Hurwitz, D., Dunlop, D., Song, J., Cahue, S., Hayes, K., & Sharma, L. (2007). The relationship between toe-out angle during gait and progression of medial tibiofemoral osteoarthritis. Annals of the rheumatic diseases, 66(10), 1271-1275.)

Based on previous suggestion, itis clear that inferences cannot be made by the results obtained by one subject. That is a critical limitation that reduces the significance of the manuscript.

Reviewer 2 Report

This is an interesting paper. However, please consider the following points:

 

1) throughout there are abbreviation's provided in text (TF contact force,KAM,GRF etc). Whilst these are mostly defined in the abstract, please also define them in the main body of text. 

2) line 46 - toe-in and toe-out would lead to immediate quadriceps and hamstrings co-contraction increases in healthy adults. - please provide a reference

3) line 48 - how does It has been reported that patients with knee OA typically exhibit greater muscle activation and co-contraction of the lateral thigh muscle group, and greater muscle activation duration of the periarticular knee muscles during natural walking - how does this relate to the previous sentence 

4) line 51 - The effective outcome of FPA gait modification is mainly on the reduction of the first peak of KAM in a short period of time. - reference needed

5) please discuss the impact of the use of a female on the results. For instance, how does the wider hips typical with females impact the results?

6) line 85 - how were the muscles identified so that the EMG electrodes could be attached. I.e. were the locations SENIAM approved

7) line 93 - please provide detail on how the metronome was used? were the steps synchronised with this?

8) line 97and 99 - Change 'we' to a third person term

9) how were the force plate data used in the inverse dynamics calculation? did they interpolated or extrapolate the GRF or kinematic data

10) line 129 - Data processing for the recorded markers, EMGs, and GRFs were based on the previous study - please provide detail.

11) line 130 - delay of 312ms - what do you mean by this? electromechanical delay? why would this impact normalisation?

12) line 132 - what filter was used

13) line 135 - remove highlight

14) line 155 - instead of superior-inferior this is typically referred to as vertical forces. please amend.

15) Throughout the results it would be useful to present % differences at key phases

16) line 199 - please check throughout for formatting and spelling errors

17) line 203 - KAM is widely accepted as the surrogate measure for the TF joint load and KAM is affected by GRF directly. - provided reference

18) line 214 - change would to could as it cannot be certain that this would be the case all of the time.

19) - please make it clearer throughout what this paper is adding to the literature on this topic and how it is filling gaps that prevent the treatment of individuals

20) - In the methods please specify how the change in foot position was bought about and how it was controlled.

21) - please specify how the results can be used in the future.

22) - please comment on whether this study could be extended to a larger group of different walking gaits for statistical analysis