Finite Element Simulation of Dry Wear of Prosthesis Made of UHMWPE and 316LVM Stainless Steel

Response to reviewer 1’s comments

1. Summary

Thank you very much for taking the time to review the manuscript. I would like to express my sincere thanks to the reviewers and Editors of the MDPI journal coatigs for giving the comments, and the opportunity to revise the article to improve it for publication.

Below, you will find the detailed responses and corresponding revisions/corrections highlighted/in the change control in the resubmitted files.

2.

Evaluation questions

general

Reviewer evaluator

Answers and reviewers

Does the introduction provide sufficient background and include all relevant references?

Must be improved

The introduction was made more extensive, highlighting the main objective of the Project, more current bibliographic references were consulted on the subject, and more emphasis was given to the originality of the subject.

Is the research design appropriate?

Are the methods adequately described?

Are the results clearly presented?

Are the conclusions supported by the results?

Yes

Must be improved

Must be improved

Must be improved

no comment

Each stage of the research was described in more detail in the methods section.

The results section has been rewritten.

The conclusions were supported by the following results

3. Point-by-point response to comments and suggestions for authors.

Comments 1: Please check the text for grammar and typographical. Some parts are in Spanish, (Table 5, Conclusion).

Response 1: Thank you for pointing this out. I/We agree with this comment. Therefore, we have:

A complete revision of the text in terms of grammar and spelling was carried out, in addition to verifying the extensive editing of the article in the English language.

Comments 2: Authors must clearly state the originality in this study.

Response 2:  I agree with this comment and amendments were made to emphasize this point.

More current bibliographic references on the subject were used, and emphasis was given to the originality of the project.

Added in the introduction lines 48 to 52, 56 to 65, 74 to 82, 99 to 112 and 126 to 160.

Comments 3: For clearly giving the state-of-the-art in the field, authors should also discuss the wear behavior of UHMWPE under various conditions. Here some suggested papers.

           https://doi.org/10.1002/app.50245

          https://doi.org/10.1115/1.555362

Response 3: We are grateful for the suggestion and proceeded to do the following:

The suggested papers were analyzed, the author Selim Gurgen developed a composite material of UHMWPE and SiC, which, although it is not an application for biomaterials, the values of the thermal properties were taken into account to apply it to our project. Sara Young uses a knee motion simulator to replicate the conditions observed in vivo, taking into account the temperature conditions caused by friction between components.

From both articles it was corroborated that temperature is a key variable for the wear process, taking the thermal conditions as part of the simulation to analyze the during the simulation of the reciprocating sliding test.

The bibliographic references were added in the introduction part, in the lines of la 99 a la 112.

It was also mentioned in the introduction as an objective of the research, in lines 139 to 148.

The simulation assigned to the UHMWPE material its thermal properties in Table 2, line 232, as well as its melting and transition temperatures, Table 3, line 240.

Comments 4:   How did authors decide on the parameters used in the testing?

Response 4: Thank you for pointing this out. We agree with this comment. We have therefore proceeded to do the following:

The load value parameter used for the reciprocating motion test was 10 N because data from the analysis during the walk cycle was used.

Added an explanation in the materials and methods section from line 189 to 197.

Comments 5:   Did they consider P-v diagram for the tested materials?

Response 5: Thank you for pointing this out.

A pressure-velocity diagram was not elaborated, since the load and speed used were constant. To obtain the friction coefficient, 3 different loads at the same speed were taken into consideration. The following will be considered for future work.

Comments 6:   Did authors fabricate the UHMWPE, or directly supplied from the market? Details must be given.

Response 6: The material used for the tests was UHMWPE of type GUR 1020 provided by a Mexican company that manufactures joint prostheses. In the text it is found from line 162 to 167.

Comments 7:  Table 3:  How did authors obtain the data? If from the literature, please cite it. 

Response 7: Thank you for your comments. The values of the elastic properties of the material were obtained through nanoindentation tests, the other parameters such as density and thermal properties were obtained from bibliographic references. The thermal properties were added to Table 3 and the units were changed to match those used in the software.

It was mentioned that the 316 LVM stainless steel ball is modeled as a solid of the discrete rigid type, so no properties were assigned to it.

The lines in the article that support this part are: 226 to 243.

Comments 8:   Numerical modeling should be given in detail. Main steps, such as mesh optimization, element types, time integration scheme, material modeling, boundary conditions, contact model etc. must be described in detail.  

Response 8:  We appreciate the observation and this point was addressed with a more detailed description of the geometrical characteristics, boundary conditions, contact conditions, size and type of element, as well as the type of explicit analysis used. This part is specified in the section of geometric modeling by FEM in line 203 to 304.

In the section on geometric modeling in FEM, wear model and programming language in Fortran.

Comments 9:  Wear mechanism on the materials must be discussed well. A detailed discussion must be given in the light of analysis results  

Response 9:  We appreciate your comment, the wear model part on line 265 to 287, the results on line 306 to 394 and the discussion on line 396 to 456 were rewritten.

Comments 10:  What is the contribution of FEA in this concept? Authors must properly give the basis of the study.  

Response 10:  Thank you for your comment, the importance of the use of the FEM is mentioned in the introduction, in lines 113 to 116 and 139 to 160. In conclusions from line 471 to 497.

Comments 11:  Conclusions must be rewritten highlighting the main outputs.

Response 11:  The conclusions section was rewritten trying to highlight the contributions of line 458 to line 497.

Note: the text in red was added, or rewritten, taking into account the referees' suggestions for improving the article.

Response to reviewer 2’s comments

1. Summary

Thank you very much for taking the time to review the manuscript. I would like to express my sincere thanks to the reviewers and Editors of the MDPI journal coatigs for giving the comments, and the opportunity to revise the article to improve it for publication.

Below, you will find the detailed responses and corresponding revisions/corrections highlighted/in the change control in the resubmitted files.

2.

Evaluation questions

general

Reviewer evaluator

Answers and reviewers

Does the introduction provide sufficient background and include all relevant references?

Must be improved

The introduction was made more extensive, highlighting the main objective of the Project, more current bibliographic references were consulted on the subject, and more emphasis was given to the originality of the subject.

Are all references cited relevant to the research?

Is the research design appropriate?

Are the methods adequately described?

Are the results clearly presented?

Are the conclusions supported by the results?

Must be improved

Must be improved

Must be improved

Must be improved

Must be improved

The materials and methods section was rewritten.

Each stage of the laboratory tests was written, and a flow chart of the methodology was added.

Each stage of the research was described in more detail in the methods section.

The results section has been rewritten.

The conclusions were supported by the following results

3. Respuesta punto a punto a los comentarios y sugerencias para los autores.

Comments 1: The authors must revise the title for table 3 to table 2."

Response 1: Thank you for pointing this out. I/We agree with this comment. Therefore, we have:

The titles in table 2 and, 3 were checked to ensure that they are in the correct format. Line 232, and 240

Comments 2: The authors must focus on how the maximum contact pressure can decrease over time.

Response 2:  I agree with this comment and amendments were made to emphasizes this point. In Figure 9 the final result of the CPRESS is mentioned, more emphasis is given to the elasto-plastic deformation PEEQ to observe the repercussion that the temperature has on this variable. This part is mentioned in the results Finite element contact pressure analysis section from line 343 to 379.

Comments 3:  The authors must provide at least three latest citation references from 2022–2024

Response 3: The current references have been added in the introduction, No. 1 for the year 2022, No. 4 for the year 2023 and No. 15 for the year 2022.

In the introduction part lines 39 to 44 reference No.1, line 56 to 66, reference No.4 and in line 135 to 148, reference No. 15.

In References on line 504, 513 and 545 respectively.

Comments 4:   The authors must explain the importance of applying the 316LVM steel exhibited to offer better flexibility and higher low-cycle fatigue resistance.

Response 4: Thank you for pointing this out. We agree with this comment. We have therefore proceeded to do the following:

The most vulnerable material in the articulated knee assembly are the pins and inserts manufactured with UHMWPE material and this is exposed to adhesive and fatigue wear. Stainless steel is the first material used for the manufacture of prostheses in Mexico, so it was decided to carry out tribological tests with the use of both materials.

Comments 5:   The author must provide the abbreviation for “C3DR8”, and ASTM.

Response 5: Thank you for pointing this out.

Se realizaron las descripciones de las abreviaciones del tipo de elementos R3D4, 3D8T y ASTM en el párrafo que está en las líneas 208 a la 221, y en la línea 183.

Comments 6:     The authors must revise the spelling for Fig. 8, and 9.

Response 6:  A complete revision of the text in terms of grammar and spelling was carried out, in addition to verifying the extensive editing of the article in the English language.

Comments 7:   The authors forget to give the name for Fig.12.  

Response 7: Thank you for your comment. The titles of each figure have been revised.

Comments 8:   The authors must focus in the section on the effect of contact pressure and load on the wear of prostheses made of UHMWPE.

Response 8:  Thank you for your comment. The results section focuses more on the effect of plastic deformation and contact pressure to perform the analysis of wear mechanisms. It is found in the Finite element contact pressure analysis section of results line 343 to 379.

Note: the text in red was added, or rewritten, taking into account the referees' suggestions for improving the article.

Response to reviewer 3’s comments

1. Summary

Thank you very much for taking the time to review the manuscript. I would like to express my sincere thanks to the reviewers and Editors of the MDPI journal coatigs for giving the comments, and the opportunity to revise the article to improve it for publication.

Below, you will find the detailed responses and corresponding revisions/corrections highlighted/in the change control in the resubmitted files.

2.

Evaluation questions

general

Reviewer evaluator

Answers and reviewers

Does the introduction provide sufficient background and include all relevant references?

Must be improved

The introduction was made more extensive, highlighting the main objective of the Project, more current bibliographic references were consulted on the subject, and more emphasis was given to the originality of the subject.

Are all references cited relevant to the research?

Is the research design appropriate?

Are the methods adequately described?

Are the results clearly presented?

Are the conclusions supported by the results?

Must be improved

Yes

Must be improved

Must be improved

Must be improved

Current references have been added in the introduction, results and discussion.

no comment

Each stage of the research was described in more detail in the methods section.

The results section has been rewritten.

The conclusions were supported by the following results

3. Point-by-point response to comments and suggestions for authors

Comments 1: The literature review is selective. The authors should indicate works directly related to the topic and scope of research and, against this background, indicate elements of novelty and contributions to science.

Response 1: Thank you for pointing this out. I/We agree with this comment. Therefore, we have:

Articles directly related to the topic were consulted, the main objective of the research, the methodology, the conclusions and the results were restructured and written.

Materials and methods section, line 161 to 304, results, line 305 to 394 and conclusions from line 457 to 497.

Comments 2: The authors conducted tribological tests, the methodology of which is described in Chapter 2. Due to the fact that these are verification tests for a simulation model, they require clarification of the test conditions - preparation of tests as well as procedures and measurement results regarding test samples and counter-samples. The methods require indication of research equipment and their accuracy. Table 1 reproduces information from the text of the manuscript. Were the results replicated? How reliable are the results?

Response 2: We agree with this comment and amendments have been introduced to emphasize this point.

The Materials and Methods section describes in detail the preparation of the samples, as well as the conditions for the laboratory tests and, description of the equipment used, in lines 161 to 201. The conditions used in the wear tests are shown in Table 1 on line 198. In the discussion section, the limitations of the project are mentioned on lines 453 to 456.

Comments 3:  The simulation tests were carried out with low resolution and the reviewer also has doubts about the kinematics of the simulated system. Simulation research is carried out in specialized software, which by definition has limitations. The limitations of the software and the conditions for conducting the simulation should be clearly described to be reliable.

Response 3: A mesh refinement was performed on the upper part of the contact specimen, the geometric modeling conditions, boundary, element type and size, and test simulation conditions are shown in line 202 to 263.

Comments 4:   The authors present three equations for wear, which they define as volumetric wear, linear wear and Archard’s wear. The equations determine certain indicators based on experimental studies. This section is unclearly defined, the models are linear, the symbol designations are not well defined and have no unit of measurement, and are not unambiguous. In this case, the authors use proprietary software - the authors should present the data processing algorithm.

Response 4: In the section on materials and methods, the wear model describes in detail the variables and the way to obtain the data used.

In the wear model section from line 264 to 267. Programming in Fortran language from line 292 to 304.

Comments 5:  Chapters 3 and 4 require supplementation and rewording, because the presented research results do not result directly from the research methodology. Research conclusions should be numbered and based on specific research results. The article requires a major revision.

Response 5: Thank you for pointing this out.

In the wear model section from line 264 to 267. Programming in Fortran language from line 292 to 304.

Comments 8:   Chapters 3 and 4 require supplementation and rewording, because the presented research results do not result directly from the research methodology. Research conclusions should be numbered and based on specific research results. The article requires a major revision.

Response 8:  Item 3 on results was completely reworded and items 4 and 5 on discussion and conclusions were rewritten, respectively, from line 395 to 497.

Note: the text in red was added, or rewritten, taking into account the referees' suggestions for improving the article.