Polymer-Based Materials Built with Additive Manufacturing Methods for Orthopedic Applications: A Review

Round 1

Reviewer 1 Report

The article provides an overview of various 3D-printed polymers and their composites for orthopedic applications published in the literature since 2010. The aim is to illustrate how these materials manufactured by 3D printing can be used to overcome the issues related to the current solutions used for musculoskeletal disorders, such as auto-transplantation, xeno-transplantation, and implantation of artificial mechanical organs. The authors focused their attention mainly on the following polymers and their composites: PLA, PEG, PCL, PGA and PLGA, PEEK, taking into account various filler and their influences on mechanical, biological and mechanobiological properties. In this review, it is possible to read thorough expositions of the Additive Manufacturing technologies employed for each material and the potential applications in the orthopedic field. The article is well-organized, and all the above-mentioned key factors have been summarized in tables at the end of each sub-section. The references are exhaustive, and the literature review includes many recent papers. On these bases, I recommend the publication of this review paper.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript highlights the importance of 3D printing technology for orthopedic applications and furthermore, the article discussed in great detail the available polymer and composite materials for 3D printing, and their usage for medical applications. Including the following suggestions will further improve the quality of the manuscript.

1.Introduction

Page 3, para 1, the paragraph discussed different 3D printing techniques for processing polymers and composites for orthopedic applications, but the challenges and limitations of these technologies were not provided. Some of the challenges include limitation of processing capabilities of different materials, challenges in post-processing, surface finish, and dimensional accuracy of 3d printed parts. The discussion on the above points could further improve the quality of the manuscript.

Some of the above points mentioned in the book chapter ‘Fabrication of Composite Structures via 3D Printing 2021’ Authors could refer to the comprehensive discussion about composite materials for fabrication of composite structures via different 3D printing techniques and also their applications had been provided.

Computational work plays a crucial role in getting desired performance for 3d printed parts, discussion on composite structures design such as this  ‘Minimal compliance design for metal-ceramic composites with lamellar microstructures’ can be included in the manuscript.

3 Results & discussion

If possible at the end of section 3, a Pie chart on materials and the number of investigations in the literature could provide a gist of the article.

Although the data in the Tables provide detailed info, but the text in section 3 is exhaustive to read. Providing highlights for each material, 2 to 3 bullet points about medical applications of the material, and a list of AM processes used,  pros & cons of the material for 3D printing if any, would be helpful for the reader. For example, the 3.3 PCL section is exhaustive and challenging to follow the data in the section

4. Discussion

Page 30, para2, could you elaborate on how could the data from the tables or What points to look for while selecting the 3D printing process and materials for a medical application

5. Conclusions

Could you provide challenges/ limitations, gaps in the literature, and future directions in bullet points format?  this would help readers to get an overview of the topic and future directions of the topic.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The authors' current manuscript is a significant attempt toward developing a comprehensive report on 3-D printed polymers and composites. If published, this work will be extremely useful, especially for early 3D printing and biocomposite selection researchers. The authors have included a sufficiently long list of previous works by many researchers that are pretty relevant to the current work. The manuscript needs some reorganization in order to be useful.

Since the authors mentioned in the title that this work is for '2D printed polymers and composites', the writing does not currently reflect that goal. In fact, it reads as if the goal is to introduce the polymers and their properties. I would suggest that the authors re-evaluate their work and organize it under subtitles that reflect the '3D printing techniques' and their significance in developing these materials for biological applications.

Several tables have been included in listing these materials' various properties. A comparison of such properties reflecting the 3D printing techniques is needed. A few comparisons using figures would be more useful and complementary to tables.

Tabulation of 3D printing techniques and their advantage as well as disadvantages is needed.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Thank you. The revised manuscript provides comprehensive details and looks good.

Reviewer 3 Report

NA