Analysis of Body-Slip and Buttock Pressure Characteristics during Operation of a Double-Sliding Reclining Wheelchair in Patients with Spinal Cord Injury
Round 1
Reviewer 1 Report
Excellently prepared paper. On line 181 it appears that the measurements were repeated 3 times for each configuration and each participant. It is not clear how the repeated measurements are handled in the statistical analysis. Please could the author clarify this point. Are the authors sure that the pair t-test was the best option for statistical analysis. It is conceivable that ANOVA would have enabled them to deal with the covariances such as the two different wheelchairs that were used and potentially the sex, BMI, height etc of the participants. It would be helpful in the Statistics Section to address this point. Figure 2 really represents what is happening to the skeleton rather than the whole body ... soft tissue displacements will vary under different loading conditions. So there is some dissonance between the theoretical model in Figure 2 and what was actually measured with the markers attached to the soft tissues. These limitations could be briefly address in revisions to the Discussion and the Measurements section.
Author Response
Thank you for your suggestions on improving the quality of our paper. Based on your comments, we have made the following revisions in our manuscript.
Author Response File: 
Author Response.docx
Reviewer 2 Report
General thoughts:
In the introduction, I recommend adding a review of existing solutions to introduce the reader to the current state of technology. Due to the lack of supporting illustrations, it is difficult to interpret what the authors mean by "double-sliding" and "non-sliding". The authors describe their results very vaguely. They introduced too many abbreviations that are hard to remember. Shoulder diagrams that could explain the results described in the tables.
Detailed comments:
Summary: Please add information about the obtained results in a synthetic form.
Line 46: studies show changes in body position translate into wheelchair stability. There is a work that describes the impact of changing the position of the human body on changes in the position of the center of gravity. Which translates into changes in the stability of the wheelchair.
[1] (2020). Biomechanical Relationships Between Manual Wheelchair Steering and the Position of the Human Body's Center of Gravity. Journal of biomechanical engineering, 142 (8), 081006.
[2] (2007). A method for the determination of center of gravity during manual wheelchair propulsion in different axle positions. Journal of Physical Therapy Science, 19 (1), 57-63.
[3] (1991). A technique for the determination of center of gravity and rolling resistance for tilt-seat wheelchairs. J Rehabil Res Dev, 28 (3), 51-58.
[4] (2021). The symmetric nature of the position distribution of the human body center of gravity during propelling manual wheelchairs with innovative propulsion systems. Symmetry, 13 (1), 154.
Line 99: How many patients were tested?
Line 111: Please show used wheelchairs in the picture.
Line 115: I recommend marking the given angles in the added drawing.
Line 128: How was the position of each body segment calculated in the model? It is worth referring to already published methods.
[1] (2017). The analytical method of determining the center of gravity of a person propelling a manual wheelchair. Procedia Engineering, 177,405-410.
Line 131: Please explain all symbols in the text. The equations should not constitute an element of the drawing, but a separate element to which the authors refer in the text, describing the methodology and the way of deriving the formulas in detail.
Line 42: Fonts overlap in equations
Line 147: In Figure 2 there is no indication of Vi oases Hi
Line 160: How is the mat with sensors secured so that it does not slide off the seat together with the human body.
Line 199: This table should be in the patient description place at the beginning of section no. 2
Line 194: The result section cannot start with a table. Start with text that introduces or describes the results.
Line 210: I recommend using full names with abbreviations at least in the first paragraph.
Line 206: The table does not show which point was moved. See section TBS.
Line 233: The table is not understandable. I recommend adding an additional drawing to it.
Author Response
Response to Reviewer 2 Comments
General thoughts:
- Thank you for your suggestions on improving the quality of our paper. Based on your comments, we have made the following revisions in our manuscript:
Point 1: In the introduction, I recommend adding a review of existing solutions to introduce the reader to the current state of technology.
Response 1: The introduction has been supplemented with additional information regarding the existing solutions and technologies to solve the body-slip phenomenon:
In the body-slip phenomenon, the user slides from the backrest of the wheelchair during repositioning, which may increase the shear force on the back and the compression force on the buttock; this can lead to tissue destruction and pressure sores, and excessive body-slip increases the risk of falling in the wheelchair (Figure 1) [8]. To solve the body-slip problem, Pfaff proposed “the shear-reducing” recline system, which reduces the shear forces through repositioning of the seat-to-back angle [9]. Thereafter, wheelchairs with a contoured seat back or a molded back, which maintain contact between the body and the seat, have been developed. Additionally, various studies have been conducted to derive optimal conditions by combining the tilt and recline angles of the wheelchair [7,10-13]. (page 2, lines 52-57)
Point 2: Due to the lack of supporting illustrations, it is difficult to interpret what the authors mean by "double-sliding" and "non-sliding".
Response 2: An illustration of the double-sliding mechanism has been added in the manuscript. (Figure 2 page 4, and Figure 3, page 5) We hope this improves clarity in the text.
Point 3: The authors describe their results very vaguely.
Response 3: The results have been described in more detail.
Point 4: They introduced too many abbreviations that are hard to remember.
Response 4: To improve the clarity in the abbreviations, we have defined them in their first usage in each section.
Point 5: Shoulder diagrams that could explain the results described in the tables.
Response 5: We have added a diagram in the manuscript to explain the results in the table. (Figure 5, page 10)
Detailed comments:
Point 1: Summary: Please add information about the obtained results in a synthetic form.
Response 1: We have added the synthetic results as follows:
When reclining from 100° to 130°, backrest sliding and total body-slip in the double-sliding wheelchair were significantly decreased by 21.4 mm and 16.4 mm, respectively, compared to non-sliding wheelchair, and the peak pressure on the ischial tuberosity was significantly de-creased by 8.7 kPa. Upon comparison of the buttock pressure between the initial upright posi-tion before reclining and the return upright position after repositioning, the force and mean pressure with the double-sliding wheelchair were significantly reduced compared with those with the non-sliding wheelchair. (Page 1, lines 18-24)
Point 2: Line 46: studies show changes in body position translate into wheelchair stability. There is a work that describes the impact of changing the position of the human body on changes in the position of the center of gravity. Which translates into changes in the stability of the wheelchair.
[1] (2020). Biomechanical Relationships Between Manual Wheelchair Steering and the Position of the Human Body's Center of Gravity. Journal of biomechanical engineering, 142 (8), 081006.
[2] (2007). A method for the determination of center of gravity during manual wheelchair propulsion in different axle positions. Journal of Physical Therapy Science, 19 (1), 57-63.
[3] (1991). A technique for the determination of center of gravity and rolling resistance for tilt-seat wheelchairs. J Rehabil Res Dev, 28 (3), 51-58.
[4] (2021). The symmetric nature of the position distribution of the human body center of gravity during propelling manual wheelchairs with innovative propulsion systems. Symmetry, 13 (1), 154.
Response 2: The papers recommended by you are mainly studies related to the driving stability of the wheelchairs. These studies analyzed the effect of the wheelchair trajectory on the position of the body’s center of gravity, and the variability of the position of the body’s center of gravity during wheelchair propulsion. The authors seem to have mainly studied the propulsion of the wheelchair and stability of the body’s center of gravity.
Compared to the aforementioned papers, the stability mentioned in this study corresponds to the fact that using a reclining wheelchair helps with posture control, stability, and sitting tolerance.
We tried to incorporate the papers recommended by you in our manuscript; however, trying to do so led to issues arising in the flow and structure of our manuscript. This is because this study focused on body-slip and changes in buttock pressure that occur during reclining or repositioning of the wheelchair, rather than while driving a wheelchair. Unfortunately, we cannot incorporate the proposed papers as references in our manuscript, and we hope the reviewers understand our position. We intend to refer to the recommended papers in future similar studies.
Point 3: Line 99: How many patients were tested?
Response 3: Ten patients with SCI were included in this study. (Page 3, lines 99)
Point 4: Line 111: Please show used wheelchairs in the picture.
Response 4: We have added pictures of the wheelchairs and the double-sliding mechanism used in this study. (Pages 4-5
Point 5: Line 115: I recommend marking the given angles in the added drawing.
Response 5: The experimental angles have been included in the newly added illustration. (Figure 4, page 6)
Point 6: Line 128: How was the position of each body segment calculated in the model? It is worth referring to already published methods.
[1] (2017). The analytical method of determining the center of gravity of a person propelling a manual wheelchair. Procedia Engineering, 177,405-410.
Response 6: In this study, the position of each body segment was based on the study by Aissaoui et al., which has been cited in the manuscript as a reference. (Page 5, lines 139-144)
Point 7: Line 131: Please explain all symbols in the text. The equations should not constitute an element of the drawing, but a separate element to which the authors refer in the text, describing the methodology and the way of deriving the formulas in detail.
Response 7: The descriptions of all symbols have been included in Figure 4, equations have been deleted from the figure, and descriptions have been added to the manuscript. (Page 7, lines 181-188)
Point 8: Line 142: Fonts overlap in equations.
Response 8: This has been corrected. (Page 4, line 142)
Point 9: Line 147: In Figure 2 there is no indication of Vi oases Hi.
Response 9: Definitions for Vi and Hi have been added to Figure 4. (Page 6, line 172-174)
Point 10: Line 160: How is the mat with sensors secured so that it does not slide off the seat together with the human body.
Response 10: To prevent the mat from slipping when using the wheelchair, the mat sensor was fixed to the wheelchair seat using double-sided tape. This statement has been added to the manuscript. (Page 7, lines 202-204)
Point 11: Line 199: This table should be in the patient description place at the beginning of section no. 2.
Response 11: Table 1 has been moved to Section 2.1. (Page 3)
Point 12: Line 194: The result section cannot start with a table. Start with text that introduces or describes the results.
Response 12: A description of the results has been added as text before the table. (page 8, lines 240-245)
Point 13: line 210: I recommend using full names with abbreviations at least in the first paragraph.
Response 13: The abbreviations have been defined in their first usage in each section for better readability.
Point 14: Line 206: The table does not show which point was moved. See section TBS.
Response 14: The table layout has been moved. (Page 8)
Point 15: Line 233: The table is not understandable. I recommend adding an additional drawing to it.
Response 15: We have added the figure in the manuscript. (Page 10, line 293)
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors corrected the article.
