PONE-D-20-00117

The effect of housing space on bone healing in a critical radius defect in New Zealand White rabbits

PLOS ONE

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Dr. Sakamuri V. Reddy

Academic Editor

PLOS ONE

Additional Editor Comments (if provided):

The authors studied the effect of housing space on bone healing in a critical bone defect model using rabbits. I suggest to rephrase the title “….housing environment….” . There have been reports on load bearing effects on intact bones in rabbits, but the effect of housing conditions is unknown. However, bone healing in a critical defect animal models are studied using the scaffold delivery of various factors. Therefore, I suggest the authors begin the Abstract with an introduction sentence giving a rationale with housing space/other conditions/increased mobility etc variability in studies. Abstract sections conclude that larger housing space increased physical activity and promoted bone formation. I suggest removing the repetitive part of the conclusion “suggesting that housing condition is an important factor in bone healing studies.” Introduction-section should be detailed of studies in other animal models also. Results-(line 259) They should delete the unpublished report/manuscript in preparation that “The effects of the material are presented elsewhere (Trbakovic/Mellgren et al, in manuscript)” and may include in the discussion on possible variability in effects observed as data not shown. There is no need to include citrate synthase assay method as supplemental figure as they have given citations (14-15) in Methods section.

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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

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

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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

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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

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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: The authors describe a critical size defect model in rabbits investigating the influence of the cage size on bone regeneration.

Abstract:

The abstract is written well and contains all relevant information.

Introduction:

The introduction is written well and leads to the topic.

The fact that physical activity increases BMD and decreases the risk of osteoporosis is well known and does from my point of view not really need extra animal studies.

At the end of the introduction and hypothesis was formed.

Page 3, line 43, please use numbers for quotation all the time

Methods:

In general the study protocol is not so clear to me. Why using 2 different scaffolds in very small groups to compare the cage size. It seems the study was initially planned for another purpose, also comparing the scaffolds.

Loosing 30% of the rabbits due to complications is bad. You should really think about your methods.

Methods are described well and with sufficient details. Surgical procedure is also described like performed on a high level.

How did you differ between bone of the rabbit, CPC and bone graft by µCT?

You got a high bone volume with a low bone density for the animal in the larger cages and in contrast a low bone Volume with a high bone mineral density for the animals with the smaller cages?

Can this be a matter of thresholding? I seems like you are counting more callus with low bone density in the large cage group than in the small cage group.

Due to the low number of surviving animals and the high standard deviation of Bone volume and histological data I feel your study is underpowered to answer the effect of the cage size on bone regeneration and bone mineral density.

line 67: only female rabbits - influence of oestrogen (could be mentioned in discussion)

line 98: the implant was based on one CT. Did it fit accurately on all the rabbits? Did any dislocations occur (besides fractures)?

line 98: please add the measurements of the implants

line 141: please add a photo or sketch of the surgical procedure (especially the fixation)

line 162: limping scored by one observer- Is this significant? Would it be better if it was observed by more than one person ( 2 - 3 blinded observers)?

line 164: Was this the same observer as before? If not, how can we compare the inter-individual differences?

line 201: subjective scoring: as said in line (204) blinding was not possible, is there an informative value?

line 261: two or three weeks acclimatization (compared to line 72)?

Results:

Results as well as the lost animals are described well.

You should indicate that there is significance in figure 6.

line 284: which score did you use

Discussion:

The discussion is written well. I would wish to get a few more sentences regarding the 6/20 lost rabbits. I think this is way higher than the average of other studies.

line 403: single housing means stress - could there be higher cortisol levels, therefore resulting in lower bone formation?

line 411: limitations were clearly stated

missing: Why is the bone density lower in the floor group (results line 300)? Bone density and volume of the defect size increase, when animals are active. (https://doi.org/10.1016/j.injury.2016.05.037)

Conclusion:

The conclusion is appropriate.

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Reviewer #1: No

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The effect of housing environment on bone healing in a critical radius defect in New Zealand White rabbits

PONE-D-20-00117R1

Dear Dr. Hedenqvist,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

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With kind regards,

Dr. Sakamuri V. Reddy

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

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

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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

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: 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

**********

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

**********

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: Dear authors,

Thank you for revising the manuscript.

I think it has improved substantially, congratulations!

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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