Comparison of two cable configurations in 3D printed steerable instruments for minimally invasive surgery

Costanza Culmone; Remi van Starkenburg; Gerwin Smit; Paul Breedveld

doi:10.1371/journal.pone.0275535

Peer Review History

Original SubmissionMay 7, 2022
6 Jul 2022 Decision Letter - Antonio Riveiro Rodríguez, Editor PONE-D-22-13417Comparison of two cable configurations in 3D printed steerable instruments for Minimally Invasive SurgeryPLOS ONE Dear Dr. Culmone, 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. Major concerns provided by the reviewers are related to the motivation and significance of the study as well as the statistical analyses. Please, address all the comments made by the reviewers. Please submit your revised manuscript by Aug 20 2022 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, Antonio Riveiro Rodríguez, PhD Academic Editor PLOS ONE Journal Requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. 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. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match. When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section. 3. In your Data Availability statement, you have not specified where the minimal data set underlying the results described in your manuscript can be found. PLOS defines a study's minimal data set as the underlying data used to reach the conclusions drawn in the manuscript and any additional data required to replicate the reported study findings in their entirety. All PLOS journals require that the minimal data set be made fully available. For more information about our data policy, please see http://journals.plos.org/plosone/s/data-availability. "Upon re-submitting your revised manuscript, please upload your study’s minimal underlying data set as either Supporting Information files or to a stable, public repository and include the relevant URLs, DOIs, or accession numbers within your revised cover letter. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories. Any potentially identifying patient information must be fully anonymized. Important: If there are ethical or legal restrictions to sharing your data publicly, please explain these restrictions in detail. Please see our guidelines for more information on what we consider unacceptable restrictions to publicly sharing data: http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions. Note that it is not acceptable for the authors to be the sole named individuals responsible for ensuring data access. We will update your Data Availability statement to reflect the information you provide in your cover letter. 4. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide. 5. Please include your full ethics statement in the ‘Methods’ section of your manuscript file. In your statement, please include the full name of the IRB or ethics committee who approved or waived your study, as well as whether or not you obtained informed written or verbal consent. If consent was waived for your study, please include this information in your statement as well. 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: Yes Reviewer #2: Yes Reviewer #3: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes Reviewer #3: No ****** 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 Reviewer #2: Yes Reviewer #3: 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 Reviewer #2: Yes Reviewer #3: 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 work is interesting and clearly shows the results of their research. However, I have some comments and doubts about this study: 1.- Why was a direct view used instead of a 2D view on a monitor? Although this increases the complexity of the trials, it is necessary to recreate all the conditions of the minimally invasive procedures to obtain an idea of what is happening. 2.- Do the cables that attach to the links of the instrument suffer from any fatigue? How often did you change all the cables or the instrument? Every 3 or 4 attempts? Understanding that many articulating instruments suffer from fatigue or lack of tension in the cable arrangement after 10 attempts, it would be interesting to comment on this point of the investigation. 3.- Although no differences were shown between the two configurations, parallel and multi, would crossing the cables allow to cancel the fulcrum effect at the tip of the instrument controlled by the handle? Reviewer #2: The authors compared two cable configurations for laparoscopy instruments fabricated via 3D printing. The topic is interesting, the paper is well-written and free from significant flaws. However, I suggest to accept it only after minor revisions. There are three points that can be improved: 1) In general, the authors should clearly indicate all the dimensions of the devices presented in the paper. 2) Section 3.2: it would be interesting to add more details on the 3D printing process. For example, the authors should provide the 3D models and the exact dimensions of the 3D printed parts that constitute the devices. How were these parts printed? Did the authors use printing supports? Did they postprocessed the 3D printed parts? 3) Section 4.2: can the authors comment on the choice of recruiting participants with no experience in laparoscopy? Is it expectable a difference between untrained and trained operators? Reviewer #3: What is the size of the instruments? Scales (diameter, length, etc.) are missing in the figures. For the multi configuration, how were the radii determined to avoid overlapping the cables? Cable configuration in cable-driven flexible devices is of an issue in manipulation and control. However, there are many other scientific ways (some studied by same group of authors) to tackle the problem rather than user’s intuitive performance. Motivations for the study is not well laid out. Why is this study needed, and where is the significance? Does the study intent to present superiority of one design over another? What did this study aim to confirm or conclude? Statistical analyses to decide the number of participants and number of tests are not provided. Without this, no conclusions can be drawn. The learning curve could be observed with unexperienced participants. Clarification needed on how workload and learning curve were quantified. It is intended that these tools will eventually be used in the hands of experienced surgeons, so what preference is shown by surgeons? What criteria were taken into consideration designing the tests, repetitions, etc. How was the data analyzed? There was a preference for the parallel config because the distal joint could be oriented more reliably. There is no reason given for why this was important in the context of the experiment though...In the video it appears that the tip orientation needed to be very precise in order to activate the target- it was likely harder to align the tip with such precision by using the MC, but it appeared that the initial positioning to reach the target (before the fine-tuning motions) using the MC was faster. How does that align with real laparoscopic practices? Would the effect of a small lack of precision in the tip angle be negligible or drastic for surgeons? Clarification needed on “amplification component” Figure 8 is unnecessary Figure 9: please choose more contrasting colors for your plots. It’s difficult to see the difference between PC and MC plots Figure 10: Trial is incorrectly spelt Fig. 2a: Orientation angle is mentioned, but not shown. Fig. 2b: All used parameters in that figure should be explained (alpha is missed) In center parts of Fig. 2, the vertical axis is not named. Lines 193 to 208 discuss differences in control and segments, but the purpose/result is not clear. Clinical application: The materials and manufacturing needs improvement and the device presented is only a prototype – this research is maybe at too early for user trials. ****** 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 Reviewer #2: No Reviewer #3: 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.0275535.r001
Revision 1
2 Sep 2022 Author Response Dear Editor and Reviewers, We would like to thank you for the efforts in reading our manuscript and providing useful feedback. We have carefully gone through the reviewers’ comments and created an improved version of the paper. We are glad to resubmit the new manuscript for evaluation, together with this accompanying letter answering in detail to each reviewer comment. All the modifications introduced in the revision process are highlighted in red in the text. Kind regards, The Authors Reviewer 1 This work is interesting and clearly shows the results of their research. However, I have some comments and doubts about this study: Comment 1 Why was a direct view used instead of a 2D view on a monitor? Although this increases the complexity of the trials, it is necessary to recreate all the conditions of the minimally invasive procedures to obtain an idea of what is happening. Authors We would like to thank the reviewer for this comment. We choose of using a transparent phantom to address the difficulties that users with no knowledge of laparoscopic procedures might encounter in properly visualizing the operating space through a 2D view on a monitor. Differently, by using laparoscopic view settings, the collected data would have reflected the learning curve of the participants in visualizing the space in 3D from a 2D image, more than the capacity to properly operate the device. 2D visualization would instead be recommended when testing the device with experts. For clarity, we added this consideration in Section 4.3 Experiment setup, lines 286-288. Comment 2 Do the cables that attach to the links of the instrument suffer from any fatigue? How often did you change all the cables or the instrument? Every 3 or 4 attempts? Understanding that many articulating instruments suffer from fatigue or lack of tension in the cable arrangement after 10 attempts, it would be interesting to comment on this point of the investigation. Authors We thank the reviewer for this comment. The cables were preliminarily tested before the experiments to check if they were suffering fatigue. The test did not show any particular fatigue when straightened. Once mounted on the device, cables were never changed during each individual test. Therefore, they were able to withstand a total of 48 attempts. We noticed that, due to the space between the helical elements of the handle, the cables showed possible local bends during the use of the instrument. We believe that the bending was due to the excessive force applied by the participant during the first attempts, while trying to familiarize themselves with the devices. When the instrument was used with the appropriate force, no bending or fatigue was noticed. All participants used the same device from the beginning to the end of the test, except for one participant for who damaged the device end-effector by applying excessive force. We have now added these details for clarity in the Discussion, lines 490-497. Comment 3 Although no differences were shown between the two configurations, parallel and multi, would crossing the cables allow to cancel the fulcrum effect at the tip of the instrument controlled by the handle? Authors We would like to thank the reviewer for the comment. All cables for both the multi and the parallel configuration run from the tip's distal end to the proximal end of the handle. Rotating the cables 180 degrees in the shaft would let the tip move in the opposite direction, mirroring the current tip movement. However, it will not eliminate the fulcrum effect caused by the rigid shaft, pivoting in the abdominal wall. Reviewer 2 The authors compared two cable configurations for laparoscopy instruments fabricated via 3D printing. The topic is interesting, the paper is well-written and free from significant flaws. However, I suggest to accept it only after minor revisions. There are three points that can be improved: Comment 1 In general, the authors should clearly indicate all the dimensions of the devices presented in the paper. Authors We would like to thank the reviewer for this suggestion. We have now reported the dimensions of the devices in details in Figure 3. Comment 2 Section 3.2: it would be interesting to add more details on the 3D printing process. For example, the authors should provide the 3D models and the exact dimensions of the 3D printed parts that constitute the devices. How were these parts printed? Did the authors use printing supports? Did they postprocessed the 3D printed parts? Authors We would like to thank the reviewer for this comment. The 3D model of the two devices is used in Figure 3 to present the parallel and multi configurations. We improved the caption to clarify and refer to them as the 3D model. Moreover, we implemented Section 3.2 Fabrication with an improved description of the printing process: “The shaft was printed without any support except for the raft. The handle instead, was printed with the raft, and the internal support was made of small pillars autogenerated by the printer software. After the printing, the excess resin was removed by placing the parts in an isopropyl alcohol bath for 30 minutes. The support of the handle and the raft were manually removed. The dimensions of the printed devices slightly differ from the CAD model with a tolerance of � 0.08mm for the shaft and � 0.12 mm for the handle”. The integration can be found on lines 227-232. Comment 3 Section 4.2: can the authors comment on the choice of recruiting participants with no experience in laparoscopy? Is it expectable a difference between untrained and trained operators? Authors We would like to thank the reviewer for this comment. The experiments were carried out in March 2021 when restrictions due to the pandemic were still tight. For this reason, access to hospitals, and therefore recruiting subjects with experience in laparoscopy, was not possible. We recognize how comparing the performance between novices and experienced operators, would represents a valuable follow up study. Two different outcomes could be expected: compared to novice users, previous experience with different laparoscopic instruments (most of them with 2 degrees of freedom at the end effector) could constitute an initial obstacle, making the learning curve slower in the first trials, or could help them instead to reach faster a plateau in the learning curve, as shown in previous studies on articulating laparoscopic instruments “The trade-off between flexibility and maneuverability: task performance with articulating laparoscopic instruments”, Martinec et al., (2009). However, independently from previous experience, we would still expect a strong preference for the parallel configuration due to the similarities in orientation of the conventional steerable laparoscopic instruments. We elaborated on this point in Section 6.2, lines 499-506. Reviewer 3 Comment 1 What is the size of the instruments? Scales (diameter, length, etc.) are missing in the figures. Authors We would like to thank the reviewer for this comment. We have now indicated in details the dimension of the device in Figure 3. Comment 2 For the multi configuration, how were the radii determined to avoid overlapping the cables? Authors We thank the reviewer for this comment. The radii to avoid the overlap of the cables in the multi configuration were determined considering the printability of the instrument and the cable size. Once decided the amplification factor by fixing the diameter of the handle, the cables were placed as close as possible to each other but at the same time kept independent with dedicated grooves. Moreover, the order of the cables (clockwise, counterclockwise, and parallel) was decided considering the easiest way to mount the cables into the instrument. We improved this part in the Section 2.3, lines 156-157, and Section 3.2, lines 233-238. Comment 3 Cable configuration in cable-driven flexible devices is of an issue in manipulation and control. However, there are many other scientific ways (some studied by same group of authors) to tackle the problem rather than user’s intuitive performance. Motivations for the study is not well laid out. Why is this study needed, and where is the significance? Authors We would like to thank the reviewer for this comment. Fully mechanical cable-driven instruments have the advantage to have low maintenance costs, they make no noise, they have high sensitivity, and high speed and they directly react to the surgeon’s movement giving the haptic feedback that is missing in many robotic solutions, but more importantly, they allow simplification of the design without compromising the instrument functionality. For this reason, cable-driven mechanisms still represent a valid alternative for laparoscopic instruments. We improved the Introduction in order to highlight this point on lines 66-69. Comment 4 Does the study intent to present superiority of one design over another? What did this study aim to confirm or conclude? Authors We thank the reviewer for this comment. The study does not present the superiority of a design over another, but rather highlight and compare important weak and strong point of the new designs, that can help to improve the design of future multi-steerable laparoscopic instruments. For example, the performed tests showed a net preference for the parallel configuration over the multi configuration, proving that the independent orientation of the end-effector is a fundamental factor for subjects with no experience in steerable laparoscopic instruments. However, the multi configuration appeared to be faster in positioning the instrument to reach the target We improved the goal of the work in order to clarify the scope of the study, on lines 82-83 of the Introduction. Comment 5 Statistical analyses to decide the number of participants and number of tests are not provided. Without this, no conclusions can be drawn. Authors We would like to thank the reviewer for this comment. We agree with the reviewer on the importance of statistical analysis to decide the number of participants. However, due to the difficulties in defining the target population and the number of instruments used in the field being the instrument new in such application, we decided to base the number of participants for this study on similar studies i.e., “SATA-LRS: A modular and novel steerable hand-held laparoscopic instrument platform for low-resource settings” Lenssen et al., (2022), “The trade-off between flexibility and maneuverability: task performance with articulating laparoscopic instruments”, Martinec et al., (2009), “Comparison of Laparoscopic Steerable InstrumentsPerformed by Expert Surgeons and Novices”, Lacitignola et al., (2020), “Precision in stitches: Radius Surgical System”, Waseda, (2007), where it varies between 5 and 24. In these studies either novices, experts, or both of the categories are recruited as participants of the study. Moreover, among the 12 participants of the studies, we tried to have differences such as age or gender and different habits that could affect the performances such as playing instruments or video games. For what concerns the number of tests, a similar consideration can be drawn. We decided to organize the test in four trials per participant so that each participant could test each instrument two times and the two Groups A and B could be comparable. Moreover, we fixed the number of repetitions to 12 so that the participants had the time to first familiarized themselves with the instrument and then improve his/ her performance. A similar number of attempts have also been used by similar studies such as SATA-LRS: A modular and novel steerable hand-held laparoscopic instrument platform for low-resource settings” Lenssen et al., 2022", where the study has been conducted with novices, whereas a lower number of attempts has been used in studies that involved also expert surgeons, such as “Comparison of precision and speed in laparoscopic and robot-assisted surgical task performance” Zihni et al. (2017). We included this consideration in Section 4.2 266, 268-271, and Section 4.3 lines 315-318. Comment 6 The learning curve could be observed with unexperienced participants. Clarification needed on how workload and learning curve were quantified. Authors The learning curve was quantified for two different aspects. First, it was calculated as the difference between the average time used to perform the first run and the one to perform the last run for each instrument in the two different trials. Then the learning curve was calculated as the difference between the two groups over the four performed trials. The different drop in time is reported in percentage in the study. The workload was quantified using the NASA-TLX test which is generally used to quantify the workload of a task. The test is a self-evaluation that the participants had to fill out at the end of each trial. In the form, the participant had to mark on a scale from very low to very high how demanding the test was. The results have been evaluated by considering very low as 0 % and very high as 100 % workload. The results of the test for each trial have been plotted in Figure 12 (new Figure 11). The code used to analyze all data is available in the link of “data availability”. We improved the test to make these points clear in Section 5 lines 365-366, 388-390, and 399. Comment 7 It is intended that these tools will eventually be used in the hands of experienced surgeons, so what preference is shown by surgeons? Authors We would like to thank the reviewer for this comment. Due to the fact that the proposed instruments have not been tested by experienced operators, we can only make some considerations for what concern the possible scenarios. Either the previous experience with different laparoscopic instruments, most of them with none or 2 degrees of freedom at the end effector, would constitute an initial obstacle and would make the learning curve slower than for the novices in the first trials, or their knowledge would help them and the learning curve would reach a plateau faster than for novices, as it has been shown in previous studies when a comparison with conventional and articulating laparoscopic instruments was conducted with experts and novices (The trade-off between flexibility and maneuverability: task performance with articulating laparoscopic instruments, Martinec, 2009). The authors would expect a similar outcome for what concerns the type of instruments with a strong preference for the parallel configuration due to the similarities in the orientation of the conventional steerable laparoscopic instruments. We elaborated on this point in Section 6.2, lines 501-506. Comment 8 What criteria were taken into consideration designing the tests, repetitions, etc. How was the data analyzed? Authors We would like to thank the reviewer for this comment. The test was designed considering that the steerable laparoscopic instruments compared to the conventional laparoscopic instruments allow more precise positioning of the instruments and orientation of the end-effector. Therefore, in the designed platform each tube has a different orientation and position that can be reached only with a specific shape of the end-effector. The repetitions of the trials were decided based on the fact that each instrument had to be used two times to have a comparison among the two groups and, in case, notice differences or influences of one instrument over the other. For each run, all the targets need to be randomly reached so that all runs could be comparable. Each trial has 12 runs so that the participants would during the first runs familiarize themselves with the instrument and then try to improve his/her performance. Moreover, a comparable number of attempts has been used in similar studies such as “SATA-LRS: A modular and novel steerable hand-held laparoscopic instrument platform for low-resource settings” Lenssen et al., 2022", where the study has been conducted with novices, whereas a lower number of attempts has been used in studies that involved also expert surgeons, such as “Comparison of precision and speed in laparoscopic and robot-assisted surgical task performance” Zihni et al. (2017). Data have been analyzed using the Matlab script available in the data availability of this article. We now added this consideration to clarify in Section 4.3 lines 315-318, and 336. Comment 9 There was a preference for the parallel config because the distal joint could be oriented more reliably. There is no reason given for why this was important in the context of the experiment though... Authors We would like to thank the reviewer for this comment. During surgery precision and accuracy are extremely important to guarantee the success of the procedure. Having a fast and reliable orientation of the surgical instrument allow reaching the target while preserving critical surrounding areas. Therefore, in the experiment, we aimed at recreating in simulating environment the movement that the surgeon might perform when navigating during a laparoscopic procedure with particular importance to the precision in the orientation of the instrument. We improved Section 4.3 in lines 278-281. Comment 10 In the video it appears that the tip orientation needed to be very precise in order to activate the target- it was likely harder to align the tip with such precision by using the MC, but it appeared that the initial positioning to reach the target (before the fine-tuning motions) using the MC was faster. How does that align with real laparoscopic practices? Would the effect of a small lack of precision in the tip angle be negligible or drastic for surgeons? Authors We would like to thank the reviewer for this comment. When using conventional laparoscopic instruments, the surgeons lose dexterity, and, therefore, precision becomes also a challenge. The use of steerable laparoscopic instruments allows the surgeon to be more precise and accurate, as shown in previous studies by Weseda et al. "Precision in stitches: Radius Surgical System". In our case, the lack in the precision of the MC would probably not be an issue for standard procedures, as it can be compared to commercialized steerable laparoscopic instruments, however, the high precision of the PC might allow procedures that are nowadays not possible due to such a lack of precision. We included this consideration in the Discussion, Section 6.1, lines 463-464 and 470-473. Comment 11 Clarification needed on “amplification component” Authors We would like to thank the reviewer for this comment. We specified in the text that the “amplification is the distal rigid part of the handle (Section 3.1 line 191), and we improved Figure 3 so that also the amplification component is named in it. Comment 12 Figure 8 is unnecessary Authors We would like to thank the reviewer for this comment. We moved Figure 8 to the supplementary materials. Comment 13 Figure 9: please choose more contrasting colors for your plots. It’s difficult to see the difference between PC and MC plots Authors We would like to thank the reviewer for this comment. We changed the color that represents the parallel configuration from green to yellow in order to improve the contrast. All figures and test have been changed accordingly. Comment 14 Figure 10: Trial is incorrectly spelt Authors We would like to thank the reviewer for this comment. We corrected the spelling of Trial in the previous Figure 11, now Figure 10. Comment 15 Fig. 2a: Orientation angle is mentioned, but not shown. Authors We thank the reviewer for this comment. We included the orientation angle in Figure 2. We named it beta in the text and in the figure. Comment 16 Fig. 2b: All used parameters in that figure should be explained (alpha is missed) Authors We thank the reviewer for this suggestion. We added the explanation of the alpha parameter in the text, line 114. Comment 17 In center parts of Fig. 2, the vertical axis is not named. Authors We thank the reviewer for this comment. We added the name of the vertical axis in the central parts of Fig 2. Comment 18 Lines 193 to 208 discuss differences in control and segments, but the purpose/result is not clear. Authors We would like to thank the reviewer for this consideration. We improved Section 3.1 (lines 215-218) by explaining that, due to the equal length of the steerable shaft, the two prototypes are able to cover the same workspace. Moreover, the identical appearance of the two prototypes allows for comparing the cable configuration performance without influencing the participant in the test. Comment 19 Clinical application: The materials and manufacturing needs improvement and the device presented is only a prototype – this research is maybe at too early for user trials. Authors We would like to thank the reviewer for this comment. We agree with the reviewer about the early stage of such research to directly be used in a trial. In this work, we presented a first evaluation of the maneuverability of our 3D-printed steerable instruments. The presented test is fundamental, especially for inexperienced subjects to have an immediate impression of the possible use of such instruments. In case of complete failure of our studies with subjects that would have given up in the middle of the test or an increase of time during different trials would have suggested a possible need for modification of our approach in investigating 3D printed steerable instruments. On the contrary, the feedbacks were all positive and the subjects enjoyed participating in the training. We implement this consideration in the Discussion, Section 6.1, lines 473-476. Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0275535.r002
19 Sep 2022 Decision Letter - Antonio Riveiro Rodríguez, Editor Comparison of two cable configurations in 3D printed steerable instruments for Minimally Invasive Surgery PONE-D-22-13417R1 Dear Dr. Culmone, 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 for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, 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, Antonio Riveiro Rodríguez, PhD Academic Editor PLOS ONE 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: I consider that the authors have made the necessary changes to publish the document; therefore, my decision is to accept the article. Reviewer #2: The authors satisfactorily replied to all my observations. In my opinion, the paper can now be published in its current form. ****** 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 ******** https://doi.org/10.1371/journal.pone.0275535.r003
Formally Accepted
26 Sep 2022 Acceptance Letter - Antonio Riveiro Rodríguez, Editor PONE-D-22-13417R1 Comparison of two cable configurations in 3D printed steerable instruments for Minimally Invasive Surgery Dear Dr. Culmone: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. 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 plosone@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. Antonio Riveiro Rodríguez Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0275535.r004

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .