Functional dynamic prosthesis alignment maintained across varying footwear using a modular prosthetic ankle-feet system

Nicole R. Walker; Myrriah P. Laine Dyreson; Juan E. Cave II; Kali R. Mansur; Kelly J. Yun; John M. Looft; Andrew H. Hansen

doi:10.1371/journal.pone.0323647

Peer Review History

Original SubmissionJuly 1, 2024
1 Jul 2024 Author Response https://doi.org/10.1371/journal.pone.0323647.r001
22 Aug 2024 Decision Letter - Arezoo Eshraghi, Editor PONE-D-24-25730Functional dynamic prosthesis alignment maintained across varying footwear using a modular prosthetic ankle-feet systemPLOS ONE Dear Dr. Walker, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Oct 06 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Thank you for stating the following in the Competing Interests section: "I have read the journal's policy and the authors of this manuscript have the following competing interests: Dr. Andrew Hansen is an inventor on a pending patent related to the modular prosthetic ankle-feet system described in this project. The pending patent is owned by the United States Department of Veterans Affairs." Please confirm that this does not alter your adherence to all PLOS ONE policies on sharing data and materials, by including the following statement: ""This does not alter our adherence to PLOS ONE policies on sharing data and materials.” (as detailed online in our guide for authors http://journals.plos.org/plosone/s/competing-interests). If there are restrictions on sharing of data and/or materials, please state these. Please note that we cannot proceed with consideration of your article until this information has been declared. Please include your updated Competing Interests statement in your cover letter; we will change the online submission form on your behalf. 3. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Partly ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: I Don't Know ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: This paper assessed if the RECOVER modular prosthetic ankle-feet system can maintain sagittal plane alignment when prosthesis users change their shoes, each having different heel heights. The researchers completed this by attaching the RECOVER system to the participant’s socket, have the participant wear three different pairs of shoes with varying heel heights, and collect motion capture and force plate data to analyze roll-over shape to determine if the anterior-posterior alignment was maintained. I have split my review into major and minor comments. Major comments: The authors specifically investigate the anterior posterior shift of the prosthesis user’s rollover shape. There is no information stating why the anterior posterior shift is important and should be researched. The authors need to add a paragraph explaining why this is an important metric to investigate, including but not limited to what happens if the anterior posterior shift is too drastic. One of the main points being made in the paper is that their system does not dramatically change rollover shape. However, it is not clear how sensitive roll over shape is to relevant variables in general (alignment, stiffness, etc.). For instance, is it possible that changes to prosthesis stiffness or alignment would similarly not impact roll-over shape, even though we know that they have other different effects on gait? Overall, the argument that rollover shape is little changed and thus the device works, is missing validation of the sensitivity of rollover shape to detect meaningful differences in gait / prosthesis mechanics. This should be addressed through an explicit comparison with other variables in prior published literature. The majority of the needed information is not directly in the paper but rather only found in the references which made reading this challenging. The RECOVER ankle-feet system is only briefly explained without enough information to know exactly how the system works. The authors need to add this information into this paper and not just rely on the reference. Furthermore, roll-over shape is not an outcome metric that is easy for most people to understand. Since roll-over shape is the main outcome measure, the authors need to add sufficient detail in the paper about what it is and how it is found, not just relying on the references. Prosthetic feet have changed measurably since 1986, therefore, it may not be correct to assume that the clinically acceptable parameter of 1.6 cm found in the Zahedi paper would hold true for prosthesis users today. The prosthesis users in the Zahedi paper only used Sach or uniaxial prosthetic feet from back then which cannot be fairly compared to newer flexible keel feet for those with the functional level of K2 or the energy storage and return (ESR) feet used by those with the functional level of K3. This may also hold true for the sockets, liners, and suspension that were used in the 1980’s compared to today’s technology. The authors may not be able to change this issue for this current publication but may be something to be aware of for their future research. Minor comments: The authors mention that there are “several products available that allow prosthesis users to adapt their alignment for different footwear” but then alignment becomes the focus, specifically how patients have a hard time aligning their own prosthesis correctly. Products and adjusting prosthesis alignment are different unless the product is a wrench. The authors should add a section explaining hydraulic feet, what these products are lacking, and how their system may be better for prosthetic users. For proper use of the RECOVER ankle-feet system, the prosthesis user would need a specific 3D printed foot for each of their shoes that have a unique heel height (in other words, multiple prosthetic feet). Some prosthesis users will be fine with this and some will not. The authors should consider mentioning this as a possible limitation. The authors should add more references pertaining to current prosthetic feet used in clinic, alignment, biomechanics of prosthesis users, the impacts alignment can have on the users, and rollover shape. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy . Reviewer #1: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0323647.r002
Revision 1
12 Dec 2024 Author Response We greatly appreciate the reviewer’s thoughtful evaluation of our manuscript. Please see our responses to the reviewer. Reviewer 1: “The authors specifically investigate the anterior posterior shift of the prosthesis user’s rollover shape. There is no information stating why the anterior posterior shift is important and should be researched. The authors need to add a paragraph explaining why this is an important metric to investigate, including but not limited to what happens if the anterior posterior shift is too drastic.” Additional information and citations have been added to the introduction to further describe rollover shape and the anterior posterior shift (referred to as the x0 location of the center of the arc). Additionally, further information has been included to describe the influence of heel height on the x0 location, the primary variable of interest for this pilot work. See lines 48-58 and 65-75 in the tracked changes manuscript. “One of the main points being made in the paper is that their system does not dramatically change rollover shape. However, it is not clear how sensitive roll over shape is to relevant variables in general (alignment, stiffness, etc.). For instance, is it possible that changes to prosthesis stiffness or alignment would similarly not impact roll-over shape, even though we know that they have other different effects on gait? Overall, the argument that rollover shape is little changed and thus the device works, is missing validation of the sensitivity of rollover shape to detect meaningful differences in gait / prosthesis mechanics. This should be addressed through an explicit comparison with other variables in prior published literature.” Citations reporting the sensitivity of rollover shape (and more specifically of the x0 location) have been added in lines 55-58 in the tracked changes manuscript. “The majority of the needed information is not directly in the paper but rather only found in the references which made reading this challenging. The RECOVER ankle-feet system is only briefly explained without enough information to know exactly how the system works. The authors need to add this information into this paper and not just rely on the reference. Furthermore, roll-over shape is not an outcome metric that is easy for most people to understand. Since rollover shape is the main outcome measure, the authors need to add sufficient detail in the paper about what it is and how it is found, not just relying on the references.” Additional detail describing the RECOVER ankle-feet system has been added in line 34-42 of the tracked changes manuscript. An additional figure (Figure 2) has been added to illustrate the ankle-foot rollover shape as it applies to measuring this socket based metric, and additional information about rollover shape and arc center location have been added in lines 48-58 and 65-75 in the tracked changes manuscript. “Prosthetic feet have changed measurably since 1986, therefore, it may not be correct to assume that the clinically acceptable parameter of 1.6 cm found in the Zahedi paper would hold true for prosthesis users today. The prosthesis users in the Zahedi paper only used Sach or uniaxial prosthetic feet from back then which cannot be fairly compared to newer flexible keel feet for those with the functional level of K2 or the energy storage and return (ESR) feet used by those with the functional level of K3. This may also hold true for the sockets, liners, and suspension that were used in the 1980’s compared to today’s technology. The authors may not be able to change this issue for this current publication but may be something to be aware of for their future research.” The authors certainly acknowledge that prosthetic feet technology has changed considerably since Zahedi’s publication in 1986. However, this publication remains (to our knowledge) the most meaningful piece of literature exploring the clinically acceptable variability of anterior-posterior alignment among transtibial prosthesis users. An acknowledgment of the potential limitation of the age of Zahedi’s publication has been added to the Discussion section in lines 217-223 in the tracked changes manuscript. “The authors mention that there are “several products available that allow prosthesis users to adapt their alignment for different footwear” but then alignment becomes the focus, specifically how patients have a hard time aligning their own prosthesis correctly. Products and adjusting prosthesis alignment are different unless the product is a wrench. The authors should add a section explaining hydraulic feet, what these products are lacking, and how their system may be better for prosthetic users.” Additional information about currently available prosthetic feet technologies, including heel height adjustable feet and feet with hydraulic or microprocessor-controlled ankles, and their adaptability to heel height has been added to the discussion section in lines 187-189 and lines 194-198. “For proper use of the RECOVER ankle-feet system, the prosthesis user would need a specific 3D printed foot for each of their shoes that have a unique heel height (in other words, multiple prosthetic feet). Some prosthesis users will be fine with this and some will not. The authors should consider mentioning this as a possible limitation.” An additional potential limitation to using the RECOVER ankle-feet system has been added in lines 210-217. “The authors should add more references pertaining to current prosthetic feet used in clinic, alignment, biomechanics of prosthesis users, the impacts alignment can have on the users, and rollover shape.” We believe the additional information and citations provided in addressing the previous reviewer comments also include this request and offer greater clarity to the reader. Attachments Attachment Submitted filename: Response to Reviewers.pdf https://doi.org/10.1371/journal.pone.0323647.r003
11 Mar 2025 Decision Letter - Yih-Kuen Jan, Editor PONE-D-24-25730R1Functional dynamic prosthesis alignment maintained across varying footwear using a modular prosthetic ankle-feet systemPLOS ONE Dear Dr. Walker, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Apr 25 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Kind regards, Yih-Kuen Jan, PhD Academic Editor PLOS ONE Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed Reviewer #2: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: (No Response) Reviewer #2: This revised manuscript offers more detail in areas lacking, specifically on RECOVER system and Figure 2. I agree that evaluating frontal and transverse kinematics are warranted, as are moments and socket comfort across longer repeated durations. Roll over is an indices, however, moment of force may support your finding. Is this system a component which could be ordered? Would it fall under any current L-Codes? ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy . Reviewer #1: No Reviewer #2: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0323647.r004
Revision 2
10 Apr 2025 Author Response 8 April 2025 Dear Editors-in-Chief, We greatly appreciate the reviewers’ thoughtful evaluation of our manuscript. Please see our responses to the journal requirements and reviewer. No changes have been made to the manuscript content. Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. All references have been reviewed and deemed up to date. Reviewer 2: “This revised manuscript offers more detail in areas lacking, specifically on RECOVER system and Figure 2.” Thank you for this feedback. “I agree that evaluating frontal and transverse kinematics are warranted, as are moments and socket comfort across longer repeated durations.” We appreciate this feedback and will keep this in mind for future work. “Roll over is an indices, however, moment of force may support your finding.” We appreciate this feedback and will expand our future work to explore ankle torque and torque-angle relationships as well as roll-over shapes. “Is this system a component which could be ordered? Would it fall under any current L-Codes?” Our group is working on technology transfer to an industry partner. The most appropriate reimbursement coding is also being determined. Sincerely, Nicole Walker Corresponding Author: Nicole Walker \| Nicole.Walker6@va.gov \| 612.467.3229 Attachments Attachment Submitted filename: Response_to_Reviewers_auresp_2.pdf https://doi.org/10.1371/journal.pone.0323647.r005
13 Apr 2025 Decision Letter - Yih-Kuen Jan, Editor Functional dynamic prosthesis alignment maintained across varying footwear using a modular prosthetic ankle-feet system PONE-D-24-25730R2 Dear Dr. Walker, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Yih-Kuen Jan, PhD Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0323647.r006
Formally Accepted
Acceptance Letter - Yih-Kuen Jan, Editor PONE-D-24-25730R2 PLOS ONE Dear Dr. Walker, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Yih-Kuen Jan Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0323647.r007

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