Title:Effects of prostaglandin E1 on callus formation in rabbit

Transcription

1 Author's response to reviews Title:Effects of prostaglandin E1 on callus formation in rabbit Authors: Pawel V Lipinsky (lipper@inbox.ru) Ivan V Sirotin (ivsir@mail.ru) Alexandr V Skoroglyadov (pskor@bk.ru) Alexey V Ivkov (drdefiler@mail.ru) Alexandr P Oettinger (iio@rsmu.ru) Alexandr B But-Gusaim (alex-ortoped@mail.ru) Evgeny E Krynetskiy (evkryn@gmail.com) Andreas J Roth (andreas.roth@medizin.uni-leipzig.de) Version:3Date:22 May 2015 Author's response to reviews: see over

2 Dear Reviewer, first we would like to thank you for your efforts and the care with which you have read and corrected our manuscript. We have carefully considered all points that were made and have addressed each point.. The corresponding changes in the text are marked in red or blue. We hope to have answered all questions correctly and ask for more feedback and comment. Best regards Andreas Roth Reviewer's 1 report Title:Effects of prostaglandin E1 on bone callus formation after the fracture in rabbits Version: 2 Date:24 April 2015 Reviewer: LeilaHarhaus Reviewer's report: Effects of prostaglandin E1 on bone callus formation after the fracture in rabbits BMC Musculoskeletal Disorders The authors present a pilotstudy to examine for the first time the effect ofsystemic PGE1 supplementation on bone healing. Therefore they use adiaphyseal fracture model of rabbit tibia. In my opinion it is an interesting ideaand worth to be further evaluated. I have some major and minor comments: 1. Title: The title is not well-written. I would suggest to use: Effects of prostaglandin E1 on callus formation in rabbit. We have corrected the title. 2. During the whole texts, the are several misspellings, please check again carefully.

3 We have checked the text again. The text was also corrected again by an English native speaker. 3. Study design: animal model: the majority of studies dealing with the examination of bone and fracture healing are performed on rat models. It is a well-established technique to perform a diaphyseal or even metaphyseal fracture ofthe tibia. A higher number of animals could be used and you statisticalevaluations would be more valid. For the text studies I would suggest to userat-models. Thank you very much for this comment. We plan to continue the experiment. We will check the use of a rat model first, reading the literature again, and then recommend to follow your advice. 4. You have to explain, why you evaluated a time period of 30 days. I assume, that for now, only callus formation was in your focus. After 35 days, a remodeling would start. Introduced into the text line 174: Regarding the time period it would have to be considered therefore in future experiments that after more than 30 days a remodeling probably will start.as the persistence of chondrocytes was interpreted as a sign of delayed bone healing by other authors after locally administered PGE1 into the mandible [26], a longer observing period should be used in future to show if bone develops. 5. In a next study, a long term analysis would be interesting to see what happens during the whole fracture healing process. See point Background: The cited references are all very old. You cite papers years old. Please find more actual ones. There are mainly older studies on this subject. We again carried out a PubMed search and a found a further paper from 2003 that answers the reviewer's questions. The literature has been inserted (marked red, line 348; Nr. 26). Other literature already cited is from 2009 and 2007.

4 7. Background: Questions to be answered:the first question (to create an adequate model ) is redundant, since the fracture model is established for a long time. Please remove. We removed this. The third question is also superfluous: the is an exact guideline, published by Parfitt et al. (Parfitt AM, Drezner MK, Glorieux FH, Kanis JA, Malluche H,Meunier PJ, Ott SM, Recker RR (1987) Bone histomorphometry:standardization of nomenclature, symbols, and units. Report of the ASBMR histomorphometry nomenclature committee. J Bone Miner Res 2: ), how to measure and describe bony structures. Dear reviewer, we are familiar with this method of histomorphometry. It should be applicable to assess the callus proliferation. We have introduced it into the text and recommend taking it into account in further studies. 8. You need to use the nomenclature of Parfitt et al. for evaluation of your samples. See point Methods: please move the statement regarding the ethical committee to the beginning of this section, state the number and only state it once. (see last paragraph methods section). This was done. 10. Please state in detail, why you administered the PGE1 over 10 days. What is your hypothesis? Introduced into the text line 136: The dosage and duration corresponds to other similar animal experiments [9, 11]. 11. Results: How did you assess the weight bearing and ROM? You should perform a gait analysis. Of course a gait analysis would be desirable, but this was not the main focus of our experiment. It was only to obtain a clinical estimate of fracture healing.

5 Therefore we changed the text line 138: The state of the health of animals was examined during the entire postoperative period. Also, the status of the operated limb (visually and manually free motion in knee and ankle joints, limping or not) and the postoperative wound conditions (visually healing, edema of soft tissues) were estimated. And line : The animals primarily showed signs of slight limping. The weight-bearing ability of the extremity and the range of active motion in nearby joints after operation were not significantly altered visually and completely restored after days in the main group and after days in the control group. 12. What happened to the fibulae? On the figures, they are broken. Correct, the fibula was not the object of our investigations. It could be evaluated in further studies. 13. It is critical, that you had so many problems in your control group (infections, nonunions). One must consider, that already during the surgery there may have occurred some mistakes? Usually, the healthy bone and its fracture healing serves as positive-control, since there the healing is optimal. Please consider. That is correct. We also consider the infections as a weak point that needs to be considered in future experiments. We see a way in planning future experiments with more animals, so that the statistical analysis is not affected. We pointed this out it in the chapter conclusion (line 278). 14. A major revision is the lack of biomechanical testing. Since you performed afirst pilot study, it might be acceptable to only perform morphologic evaluation,but the quality of bone healing can only be seen in biomechanical testing. We will perform biomechanical testing using advisable devices at the University of Leipzig 15. Please translate the Russian references.

6 This was completed. Level of interest:an article of importance in its field Quality of written English:Needs some language corrections before beingpublished Statistical review:yes, but I do not feel adequately qualified to assess thestatistics. Declaration of competing interests:i declare that I have no competing interests

7 Reviewer's 2 report Title:Effects of prostaglandin E1 on bone callus formation after the fracture in rabbits Version:2Date:5 May 2015 Reviewer:Pat O'Connor Reviewer's report: The manuscript describes the effects of systemic (subq) PGE1 treatment on tibiafracture healing in rabbits. The primary outcome measure was a qualitativeassessment of healing based on plain X-rays. Secondary histomorphometricmeasures or callus size, vascularity, and chondrogenesis, in general, support theconclusions. The novel aspect of this experiment is that systemic PGE1 treatment promotesfracture healing as most previous studies used locally applied PGE1 or PGE1 analogs. Concerns about the quality of the fractures and outcome measures detract fromthe study. For instance, the control fracture X-ray show that the fracture isseverely comminuted which would negatively impact stability and healing. An additional, quantitative measure of healing as the primary outcome measure is needed. The increased amount of chondrocytes in the 30 day experimental group is notconsistent with advanced healing, since callus cartilage is replaced with bone. Perhaps the authors could comments on why chondrocytes are still present. Major Compulsory Revisions: 1. Discuss fracture quality, that is, effects of comminutions. Introduced into the text line 111: In all animals, the tibia was fractured transversally. Fibular fractures and small tibial bone fragment had no clinical value. 2. Discuss need to quantitative, primary outcome measure. Introduced into the text line 143:

8 The primary endpoint of the study was the callus formation, radiologically assessed at defined days, and histologically assessed at day Discuss persistence of chondrocytes in experimental group. Introduced into the text line 274: Regarding the time period, future studies would have to consider that remodelling probably starts after more than 30 days. As the persistence of chondrocytes was interpreted by other authors as a sign of delayed bone healing after locally administered PGE1 into the mandible [26], a longer observing period should be used in future to show if bone really develops. 4. Experimental vs. Main group: please consistently name the group. This was done. 5. Intramedullary Osteosynthesis: What does this mean? Based upon what isdescribed the fracture was stabilized using an intramedullary rod. Introduced into the text line 124: The transverse diameter of these Bogdanov s nails was 1.2х2.4 mm; the length of the nails was determined intraoperatively and was 4 5 cm. For introduction of the nails in the intramedullary canal a supplementary 1.5 cm skin incision was made in projection of the patellar ligament. Distal to the ligamentous insertion, the intramedullary canal was opened with an awl. Then the two Bogdanov s nails were introduced. The length of the nails was chosen so that they protruded approximately 1.5 to 2 mm from the bone in order to facilitate subsequent removal. 6. Source of intramedullary rods Introduced into the text line 123: ООО ОСТЕОСИНТЕЗ, Russia, Jaroslavskaja Oblast, Gorod Ruibinsk 7. What analgesic was used to treat the rabbits? Was it an NSAID or steroid? Introduced into the text line 133: (Ketoprophenum 3 mg/kg body weight).

9 Minor Essential Revisions: Please have manuscript edited for syntax and other minor errors. This was done by a native speaker. Discretionary Revisions: Inclusion in discussion of COX-1/COX-2 and otherpge2 analogs (the EP receptor agonists). In the introduction, we wrote on the role of PGE2 (literature 17, 18 and 24). It was our intention to investigate the role of PGE1, so we did not discuss PGE2 in the discussion again. For BMC 1. Is the question posed by the authors well defined? Yes 2. Are the methods appropriate and well described? Methods are appropriate but better descriptions would be helpful. 3. Are the data sound? Noting the caveats described above, the data are sound within the limits of the outcome measures employed. 4. Do the figures appear to be genuine, i.e. without evidence of manipulation? Yes 5. Does the manuscript adhere to the relevant standards for reporting and datadeposition? Yes 6. Are the discussion and conclusions well balanced and adequately supported by the data? Could be improved by inclusion of discussion of persistentchondrocytes as noted above, as well as, data regarding role of COX-1/COX-2 infracture healing, and other PGE2 analogs. 7. Are limitations of the work clearly stated? No 8. Do the authors clearly acknowledge any work upon which they are building,both published and unpublished? Yes, intro and discussion are well referenced. 9. Do the title and abstract accurately convey what has been found? Yes 10. Is the writing acceptable? Minor errors need to be corrected, but otherwisewas easy to follow and understand. Level of interest:an article whose findings are important to those with closely related research interests Quality of written English: Needs some language corrections before being published

10 Statistical review: No, the manuscript does not need to be seen by a statistician. Declarationofcompetinginterests: I declare that I have no competing interests.