Plasma-Sprayed Osseoconductive Hydroxylapatite Coatings for Endoprosthetic Hip Implants: Phase Composition, Microstructure, Properties, and Biomedical Functions

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The provided text is comprehensive and well-detailed on the topic of endoprosthetic hip and knee implants, particularly focusing on their demand, functionality, materials, and associated research. The manuscript could be accepted for publication after some minor recommendations, and critiques to improve clarity, readability, and academic rigor.

1.The introduction jumps directly into technical details. As a suggestion, the authors may start with a brief overview of the increasing prevalence of joint disorders and the significance of endoprosthetic implants in modern medicine. This can help contextualize the subsequent technical discussion.

2. A justification of the review need, the novelty that brings in the domain could be added.

3.Another recommendation is that the authors define technical terms in an abbreviations list at the beginning of the review. On page 1, THA (total hip arthroplasty) is defined; meanwhile, on page 2, we found the abbreviation for total hip (THA), which may be confusing for readers who may not be familiar with the topic.

4.Figures are referenced but not well described in the text. Authors may include brief descriptions of the figures in the text to help readers understand their relevance without needing to refer back and forth. The figures and data presented in the text, such as Figure 17, is not described in detail, making it difficult to fully understand their implications.

5. The discussion on bond coats (page 5) is well-founded, highlighting their advantages in improving coating performance. However, the text could expand on potential limitations or challenges associated with the application of these bond coats, such as their long-term stability and compatibility with different metallic substrates. Including more information on long-term in vivo studies, clinical outcomes, and potential issues related to coating stability and performance over time would provide a more complete picture of the effectiveness of these coatings.

6. The text effectively highlights the complex trade-off between the need for porosity to support bone cell ingrowth and the requirement for coating density to prevent degradation. However, specific examples or case studies illustrating successful strategies for achieving this balance in clinical applications are lacking and could add value to the manuscript.

7. In the surface nanotopography paragraph (the same section 5.3.7. Coating porosity, surface roughness, and surface nanotopography, on page 19), the connection between theoretical findings and practical applications is somewhat vague. More explicit examples of how these findings have been translated into successful implant designs would strengthen the discussion.

8. In section 5.2. Deposition technique there is a limited discussion on alternative coating techniques. Expanding the discussion to include a comparative analysis of different coating techniques, such as suspension plasma spraying or solution precursor plasma spraying , or other deposition of biomimetic nanocrystalline apatite coatings synthesized by example by Matrix Assisted Pulsed Laser Evaporation (MAPLE) for medical applications or Combinatorial MAPLE deposition of antimicrobial orthopedic maps fabricated from chitosan and biomimetic apatite powders and their respective benefits and limitations would provide a broader perspective on coating technologies.

9. If considered appropriate, incorporating a section on recent advancements, emerging technologies, and innovative materials in implant coatings would keep the discussion current and forward-looking.

 

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In this article, the author gave a comprehensive and in-depth review on the topic of hydroxylapatite coatings for endoprosthetic hip implants prepared by the plasma-spraying technique. However, the following concerns must be addressed before its publication.

1. In page 2, line 54, “thigh” should be changed to “tight”.

2. The resolution of Figure 4 needs to be enhanced.

3. In page 7, line 290 and page 8, line 318, the texts are duplicated.

4. It is suggested to add a Table for comparing the existing coating techniques with plasma spraying.

5. In page 10, line 377, page 15, line 545 and line 556, and page 16, line 590, typos of “o” are observed.

6. The resolution of Figure 8 can be improved.

7. In page 11, line 407, please describe the meaning of “free surface”, e.g., the outermost coating surface.

8. In page 11, line 423, a colon is missing after “include”.

9. In Figure 9A, the resolution of the TEM image needs to be improved, since the ACP phase is hardly distinguished from the background.

10. In page 13, line 477, “Figure 9C” should be “Figure 10C” instead.

11. In page 13, line 491, “[49,57, 59]” can be changed to “[49,57,59]”.

12. The resolution of Figure 16 needs to be enhanced.

13. In page 19, line 677, the “-“ should be changed to “.”

14. It is suggested that a section discussing recent developments in the related fields of hydroxylapatite coatings for endoprosthetic implants can be added in the context, and more references in the recent 3-5 years can be included.

Comments on the Quality of English Language

The English is good, but spell check is required.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

    The author has addressed the raised concerns well, however, the quality of Figure 9 needs to be improved as in 9A, the structure of ACP and background cannot be distinguished; in 9B, the image is shaded by a few grey rectangular box, which is needed to be removed.

Comments on the Quality of English Language

The English is good.

Author Response

Comments to reviewer #2 report (second round).

The ACP section of the incriminated Fig. 9A does not have any structure (amorphous!).

The rectangulyr boxes shown in Fig. 9B contain the elctron diffraction pattern of brookite and ACP.