Prediction of Neural Space Narrowing and Soft Tissue Injury of the Cervical Spine Concerning Head Restraint Arrangements in Traffic Collisions

Round 1

Reviewer 1 Report

The manuscript shows the effect of the position of the car head restraint on damage to the spine and other tissues in the human body during rapid deceleration(braking).The article has a short introduction, but it is sufficient for a correct entry into the topics covered in the paper.  Next, the authors describe in an advanced way the methodology of research, as well as material models used in numerical analysis. The material models are correct and the modelling method does not raise any objections, and is described in a way that is understandable to the recipient.

Then the authors present the results obtained by using FEM analysis. The results are shown by means of graphics illustrating the position of the passenger during the impact, as well as visualization of the spine itself and the stress distribution during the analysis for the three tested positions of the car head restraint. In addition, the results show the effect of the distribution of stresses in the spinal core during impact at a given time.

The results presented by the authors were analyzed in depth and discussed in sections 3.4 and 4. The conclusions show a significant impact of the head restraint on subsequent health consequences and that even an incorrectly positioned head restraint improves passenger safety.

The research methodology and the presented results do not raise any objections and the article itself is fully comprehensive and therefore I recommend publication of the article in its current form.

Author Response

Thank you for your valuable comments and recommendation.

The introduction was updated with more recent statistics and supporting points. The last two paragraphs in the introduction were restructured and enriched with more details to highlight the significance of this work.

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors evaluate how the head restraint position affects neck injuries caused by rear-end collisions, using a detailed human model (THUMS). The results explored both the kinematic response and the anatomical source of pain. Although the study is interesting, I have some comments.

1. The statistics reported in the introduction are based on references [1]-[2], which are not so recent. Could you please add some updated references?
2. In the introduction, the state of the art and the purpose of your work need further details. Do previous studies follow a methodology similar to your study? Please stress the difference between them and the novelty of your work.
3. Conclusions are incomplete. More details about practical implications and future development of this study should be added.
4. The abstract should be adjusted according to the changes required in the previous points.
5. Please cite a reference for RCAR-IIWPG V3 standard (section 2.2) and for “The overall cervical spine kinematics were divided into three distinct phases; the S-shape, hyperextension, and rebound phases” (section 3.2).
6. In order to improve readability, each time you cite Figure 4, please specify not only the phase (i-ii-iii-iv) but also the arrangement (A-B-C) you refer to.
7. You refer to C1-C7 many times. Could you please display all their names in a figure?
8. In the caption of figure 6 please replace “C2-C5” with “C2-C3, C3-C4, C4-C5”.

Author Response

Thank you for your valuable comments and recommendation. We have updated our manuscript based on your feedback. Here are out point-to-point response to your comments:

1. The statistics reported in the introduction are based on references [1]-[2], which are not so recent. Could you please add some updated references?

The introduction was updated with more recent statistics and supporting points.

2. In the introduction, the state of the art and the purpose of your work need further details. Do previous studies follow a methodology similar to your study? Please stress the difference between them and the novelty of your work.

The last two paragraphs in the introduction were restructured and enriched with more details to highlight the significance of this work.

3. Conclusions are incomplete. More details about practical implications and future development of this study should be added.
4. The abstract should be adjusted according to the changes required in the previous points.

Two paragraphs were added to the conclusion that demonstrates how to practically protect occupants from whiplash injuries. These details were summarized at the end of the abstract.

5. Please cite a reference for RCAR-IIWPG V3 standard (section 2.2) and for “The overall cervical spine kinematics were divided into three distinct phases; the S-shape, hyperextension, and rebound phases” (section 3.2).

Both references were cited in text.

6. In order to improve readability, each time you cite Figure 4, please specify not only the phase (i-ii-iii-iv) but also the arrangement (A-B-C) you refer to.

Head restraint arrangement (A-B-C) were included with the phase (i-ii-iii-iv) when Figure 4 was referred to in the text.

7. You refer to C1-C7 many times. Could you please display all their names in a figure?

C1-C7 cervical vertebral initials were highlighted in figure 1c.

8. In the caption of figure 6 please replace “C2-C5” with “C2-C3, C3-C4, C4-C5”.

“C2-C5” was replaced with “C2-C3, C3-C4, C4-C5” in figure 6 caption.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The authors used a detailed human numerical model to study the cervical spine kinematic response to rear-end collision and predicted the potential soft tissue-level injury sites. They evaluated the effects of different head restraints on neck protection.

Minor revision:

1, If all the initials used in figures are explained in the figure legends, it will be more reader-friendly.

2, Figure 4, the authors showed the changes of shear stresses at different locations during different phases (initial, s-shaped, hyperextension, rebound) with a colorful bar along the spinal cord. If the authors could summarize the  shear stresses (Mpa) with the actual number during different phases in a graph, it will be more convincing.

Author Response

Thank you for your valuable comments and recommendation. We have updated our manuscript based on your feedback. Here are our point-to-point response to your comments:

1, If all the initials used in figures are explained in the figure legends, it will be more reader-friendly.

A full description for all the initials was included in every figure caption.

2, Figure 4, the authors showed the changes of shear stresses at different locations during different phases (initial, s-shaped, hyperextension, rebound) with a colorful bar along the spinal cord. If the authors could summarize the  shear stresses (Mpa) with the actual number during different phases in a graph, it will be more convincing.

Figure 5 summarizes the stresses (MPa) that were imposed on (a) each ligament, (b) sublevel intervertebral discs, and (c) bony vertebrae.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have replied exhaustively to the comments.