Design and 3D Printing of Low-Cost Functional Sports Devices for the Upper Limb

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This work details the process for providing children with custom, sports-oriented upper limb prosthetic devices, as well as outlining the design process (using CAD) and manufacturing (using 3D printing tools and machines). The authors highlight the importance of a human-centered, iterative approach as conditions change, in order to minimize abandonment. 5 Case studies are shown, including several biking activities, swimming and tennis.

Although it generally is well written, several Issues arise, described below:

1. Except for Figure 5, none of the case studies include figures highlighting that the people received, tested and succesfully carried out their expected activities. Although the authors mention a user satisfaction questionnaire, more importance should be placed on the process, and the replicability/reproducibility of this work.

2. Similarly, there is no Results Section, and the User feedback section is lacking some information. How many people was surveyed? after how much time?

3. Several parts, such as the slicing description, seem to be unnecessary and non valuable to the body of knowledge. Perhaps a table detailing the most important parameters, along with some additional notes would be more appropiate.

4. About half of the article has no references. A comparison between the proposed devices and the literature would greatly improve the validity and value of this work.

Some minor issues are:

1. General grammar and ortography.

2. Figure 11 has an italian comment that slipped out.

3. Some figures include photographies of low quality. Adding a diagram detailing the main parts would improve the ease of understanding.

Overall, it is a good text, adequate for this special issue.

Author Response

Comment 1: Except for Figure 5, none of the case studies include figures highlighting that the people received, tested and successfully carried out their expected activities. Although the authors mention a user satisfaction questionnaire, more importance should be placed on the process, and the replicability/reproducibility of this work.

Response 1: Images of the device being used are included in each case study, with the exception of the swimming aid. This is due to the parents denying consent to the publication of such picture. Regarding the replicability/reproducibility of our work, this is enabled by the use of a parametric CAD software: the assistive devices are designed to accommodate the needs and preferences of the end user that requested it, however each device can be easily reproduced for other people with similar needs by simply adjusting the measurements of the 3D model.

Comment 2: Similarly, there is no Results Section, and the User feedback section is lacking some information. How many people was surveyed? after how much time?

Response 2: The “Results” section was substituted for the “Case studies” section. We agree that it could be clearer to put these paragraphs under the “Results” title. We also agree that there was some information lacking in the “User feedback” section, so we added the number of people who responded to the satisfaction evaluation questions, which were administered one month after the delivery of the device. Later, communication is maintained through monthly check-ins. (pag. 6 line 201; pag. 13 lines 403-406)

Comment 3: Several parts, such as the slicing description, seem to be unnecessary and non valuable to the body of knowledge. Perhaps a table detailing the most important parameters, along with some additional notes would be more appropriate.

Response 3: We agree that the slicing description was superfluous, so we removed it. The main printing parameters were included more clearly in the text. [line 156]

Comment 4: About half of the article has no references. A comparison between the proposed devices and the literature would greatly improve the validity and value of this work.

Response 4: There are no references because of the fact that the assistive functional aids presented in this work were designed from scratch and are based on the needs and preferences of the end user by directly working with them throughout the process.

Reviewer 2 Report

Comments and Suggestions for Authors

Overall I thought this was in interesting case study, addressing specific challenges faced by individual amputees, something that is often overlooked in larger clinical studies. 

Some of the sections would benefit from being more concise, in particular the design and 3D printing processes in section 2 could be combined into a single figure with explanation, however this is not essential. It would be nice to see more information around the design rationale and choices made in each of the case studies as I feel this would help encourage further studies in similar areas. The conclusions surmise the work well, however the addition of a short discussion section would benefit the work, particularly providing insight into individual lessons learnt and process improvements made between case studies. An indication of prototype costs, and timelines would also be beneficial.

 

Below is a list of more specific comments on the paper:

 

Abstract - it would be nice to see an outcome/ conclusion particularly the 100% satisfaction rate

 

Line 107 - grammatical error - “it isi possible”

 

Section 2.1. - it was unclear if this protocol is for all e-NABLE limbs or just for this study 

 

Ines 165-187 - this section outlines the general principals of the materials used, followed by a table stating the same information. I suggest simplifying it to one form of presentation. 

 

Line 195 - what printer model specifically was used and what the infill percentage and wall count changed for enhanced strength? If this varies for the different case studies it would be beneficial to include 

 

Lines 189 - 204 - This section contains unnecessary details on printing principals. 

 

Case study 3.1 - The printing challenges and potential solutions did not add value to the report, however more detail on the design changes would be useful, particularly in the slots included for strapping. How did the straps work, did the prosthesis ‘flap’ when used or remain well fixed to the limb?

 

Case study 3.2-3.3 Was the second bicycle prosthesis an iterative improvement on the first, if so I would recommend combining them to highlight the power in used led iterations.

 

Figure 7 - The references between parts in Figure 6 and 7 could be made clearer. Providing names to parts A and B in the figures would help

 

Line 295 - Does the cone or socket refer to Figure 6. Part B?

 

Section 3.3 - How was the socket section fitted to the Child's residuum? Was this out of scope for this study?

 

Section 3.4 - The design choice to thermoform the bracket arms seemed odd. The paper mentioned the intent to keep layer orientation, however printing the entire bracket as a single piece with layers 90 degreed to the axis of the handle bars would have been the strongest orientation. And would have reduced the need for post processing. Further justification/ discussion in this section would help clarify.

 

Figure 11. There appears to be a comment left in Italian for the authors during the review “forse per chiarire la differenza tra i due modelli potremmo metterli fianco a fianco nella stessa figura” I agree with the comment to place the figures next to each other. 

 

The design in Section 3.4 appears to be similar to the Koalaa Joanie device. It would be good to reference the design as conceptual input or to highlight how others have addressed a similar issue. 

 

Section 6. Adding a comment about the use of Finite Element Analysis tools to evaluate the safety of devices in the design stage would be beneficial. 

 

Author Response

Comment 1: Abstract - it would be nice to see an outcome/ conclusion particularly the 100% satisfaction rate

Response 1:  Added (pag. 1 lines 10-12)

Comment 2: Line 107 - grammatical error - “it isi possible”

Response 2: Done (pag. 3 line 110)

Comment 3: Section 2.1. - it was unclear if this protocol is for all e-NABLE limbs or just for this study

Response 3: The innovative protocol was adopted by Io Do Una Mano, which is an official chapter of e-NABLE, however it has not been adopted yet by the global community.

Comment 4: Ines 165-187 - this section outlines the general principals of the materials used, followed by a table stating the same information. I suggest simplifying it to one form of presentation.

Response 4: We removed the table with the information on the materials used and left the information in the text only [Iines 169-190]

Comment 5: Line 195 - what printer model specifically was used and what the infill percentage and wall count changed for enhanced strength? If this varies for the different case studies it would be beneficial to include

Response 5: Several printers were used, the main ones being: Sharebot Q, Prusa MK4S, Prusa MK3S.

we need to add the printer model (page 6 lines 192-196).

Comment 6: Lines 189 - 204 - This section contains unnecessary details on printing principals.

Response 6: Removed

Comment 7: Case study 3.1 - The printing challenges and potential solutions did not add value to the report, however more detail on the design changes would be useful, particularly in the slots included for strapping. How did the straps work, did the prosthesis ‘flap’ when used or remain well fixed to the limb?

Response 7: No issues have been reported during the use of the device, which is firmly adjusted to the residual limb through thick bands. For older children and adolescents, another slot was added to have an additional neoprene band. (pag. 7 lines 226-228)

Comment 8: Case study 3.2-3.3 Was the second bicycle prosthesis an iterative improvement on the first, if so I would recommend combining them to highlight the power in used led iterations.

Response 8: The two devices were only related application-wise, not design-wise. They were made for the same child, who however presented very different needs the second time, even if it was for the same activity. Firstly, because some time had gone by, the first device did not fit properly anymore; secondly, he was going to learn to ride a bicycle without the training wheels and wanted a device with different characteristics that made him feel more safe while doing so.

Comment 9: Figure 7 - The references between parts in Figure 6 and 7 could be made clearer. Providing names to parts A and B in the figures would help

Response 9: Done (pag. 9 lines 285-291)

Comment 10: Line 295 - Does the cone or socket refer to Figure 6. Part B?

Response 10: Yes

Comment 11: Section 3.3 - How was the socket section fitted to the Child's residuum? Was this out of scope for this study?

Response 11: The dimensions of the socket were fitted to the measurements of the child, which were obtained through the parents and the analysis of the photographs. A more firm hold was intentionally avoided for safety reasons, since the child was learning to ride the bicycle without training wheels: this design enables a good control of the handlebar while allowing a fast removal of the arm in the event of balance loss.

Comment 12: Section 3.4 - The design choice to thermoform the bracket arms seemed odd. The paper mentioned the intent to keep layer orientation, however printing the entire bracket as a single piece with layers 90 degreed to the axis of the handle bars would have been the strongest orientation. And would have reduced the need for post processing. Further justification/ discussion in this section would help clarify.

Response 12: The choice to post-process the arms of the device was made to enhance layer adhesion while keeping the design suitable to be mounted on the handlebar and to hold the wooden cylinder intended for grasping.

Comment 13: Figure 11. There appears to be a comment left in Italian for the authors during the review “forse per chiarire la differenza tra i due modelli potremmo metterli fianco a fianco nella stessa figura” I agree with the comment to place the figures next to each other.

Response 13: Done and corrected (pag. 12 line 392)

Comment 14:The design in Section 3.4 appears to be similar to the Koalaa Joanie device. It would be good to reference the design as conceptual input or to highlight how others have addressed a similar issue.

Response 14:  We added the reference since the reviewer rightly highlighted the similarity with our device. The strength of our approach and design lies in the personalization of the dimensions and the possibility of having different cup shapes based on the preferred serving technique. [line 363]

Comment 15: Section 6. Adding a comment about the use of Finite Element Analysis tools to evaluate the safety of devices in the design stage would be beneficial.

Response 15: The Finite Element Analysis has not yet been carried out but will be in future developments.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper presented a general workflow for the design and realization of 3D printed customized assistive devices. It is an interesting common sense approach to solve a very practical problem. It is very unique in the sense that it does not have any equation or any numerical data. For a research paper, that is very unusual.

Strengths:

1. I want to complement the researchers. You have the courage to tackle this very practical and meaningful problem of assistive devices to help disabled, especially disabled kids.

2. The researcher took a very practical approach to problem solving.

Weakness:

1. Lack of rigorous scientific approach to the problem solving. The nature of the project is too empirical. Too ad hoc. 

2. Lack of any scientific data to support the claims. For example, if some sort of quantitative measure of certain tasks are carried out, then the time or effort it takes to complete the tasks can be measured to assess the efficacy of the assistive devices. 

Recommendations:

1. Instead of just stating 100% and 100% at row 407 and 408, the easiest thing is analyzing the survey data more extensive in a quantitative sense to prove the efficacy of the devices.

2. For the bicycle aid, since there are three different devices, some kind of tasks can be designed for example ride one loop in a park, then use the time it takes to evaluate the effectiveness of the devices. Or other tasks, the researchers should know better than me. Bottom line is that there needs some sort of quantitative measure of the devices to evaluate them.

 

Author Response

Comment 1: Lack of rigorous scientific approach to the problem solving. The nature of the project is too empirical. Too ad hoc.

Response 1: The ad hoc approach was what we aimed for and is behind the philosophy of the e-NABLE community: follow a common protocol to produce completely personalized solutions for each individual with limb differences. What we aimed to with our work is to provide a protocol that makers worldwide can follow to help each person that makes a request for assistive devices that are not available on the market.

Comment 2: Lack of any scientific data to support the claims. For example, if some sort of quantitative measure of certain tasks are carried out, then the time or effort it takes to complete the tasks can be measured to assess the efficacy of the assistive devices.

Response 2: The goal of the present paper is to propose a protocol/pipeline for the design of the type of devices described in the use cases, and therefore we deemed sufficient to have a qualitative evaluation based on the satisfaction rate of the end users. In the future, the quantitative evaluation of the efficacy of the devices design in the scope of this work can certainly be done in the way suggested by the reviewer.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors did not really address my concerns at all, so my opinion does not change. It is completely up to the editor to make this decision. 

Author Response

Comments 1: The authors did not really address my concerns at all, so my opinion does not change. It is completely up to the editor to make this decision. 

Response 1: 

We followed the reviewer's suggestions by including the 23 responses collected so far through the questionnaire (lines 402 - 434).

We also acknowledge the limitations regarding the lack of experimental testing of the devices with performance evaluations of the children who received such devices, and will have this in mind for future works in this field.

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

It seems that the authors have tried their best to address the deficiency. 

Author Response

Response: Following the Editor's advice, we have made changes in lines 431–449, by elaborating on the responses to the open-ended questions included in the "User Feedback" section