Author’s response to reviews Title: Comparison of lumbar plexus block using the axis in-plane method at the plane of the transverse process and at the articular process: A randomized controlled trial Authors:

In the background, it appears that dual guidance is novel for LPB which is not true. Both control group and intervention group used dual guidance. This is a practice followed by most clinicians as plexus is usually not visible on ultrasound imaging. In conclusion, wording "excellent" technical choice is too strong. At best we can describe it as promising as the availability of data regarding this technique is limited from this small study of 60 subjects. As pointed out by authors, future larger studies will tell us in the complication rates are comparable to convention technique of LPB. Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have rewritten this part. Background: Lumbar plexus is located between anterior 2/3 and posterior 1/3 of psoas major muscle (not in posterior 1/3). The argument is vague "the effect seems not very good." The technique of block used for the control group was as described by Doi et al. this should be referenced. Answer: Thanks very much for reviewer’s attention. It`s a very good advice. We have revised it. Methods: The methods should be written in past tense as the study has been completed, currently all the description is in the future tense. The description of randomization is still awkward although it is acceptable. The initials of attending doctors have been should be given as CY, YC and YL and not CYY. The familiarity of the anesthesiologist in performing erector spine block is not relevant to the study. Should be removed. Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have rewritten this part. I am not familiar with the ultrasound-guided approach to the sciatic nerve block. The technique described resembles Labat landmark approach. Please provide a reference to support this approach. Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have added the relevant reference. While describing control, please reference figure 1, likewise while describing beach chair method, please reference figure 2 so that it is easy for readers to understand. Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have added this information. The needle insertion point in beach chair methods is at lateral abdomen wall. This means that the needle path may encounter bowel during the procedure. The possibility of injury to bowel during the technique should be acknowledged in the discussions section. Answer: Thanks very much for reviewer’s comment. It`s a very good question. We have added this part in the discussion section. The motor assessment scale is not standard or described adequately. It looks like level 1 and level 2 have been interchanged. Please provide a reference to inform if this is a validated way of assessing motor block. Answer: Thanks very much for reviewer’s comment. We have revised this part to make it clearer and added the relevant reference. The statement "It took roughly 15 sec to do motor assessment" If this was not measured at the time of study should be deleted. Answer: Thanks very much for reviewer’s comment. We have deleted it. Important details of the intra-operative management of the subjects are missing. Did the patients receive a general anesthetic or spinal anesthetic or sedation for Surgery? If surgery was completed with just block and sedation implies high success rate of the block. Answer: Thanks very much for reviewer’s comment. The patients who involved in this study did not receive a general anesthetic or spinal anesthetic but mild sedation. We have added this information in the result section. Please specify if the trial design was superiority, equivalence or non-inferiority. The minimal clinically important has been incorrectly stated as 6.67, please delete. Answer: Thanks very much for reviewer’s comment. We have revised it. Results: Number of needle puncture is count data should be expressed in median and range (or IQR) not standard deviation. Answer: Thanks very much for reviewer’s comment. We have revised it. "There was no significant in ipsilateral sensation and motor blocking rate between two groups 5min, 15min and 30min after lumbar plexus block." The results for each time point is not presented. Answer: Thanks very much for reviewer’s comment. We have deleted it according to your previous comment since all the values are non-significant. Discussion: This section should start with important findings like epidural spread and needle visibility scores and not less important findings such as imaging, needling times and puncture attempts. Possible complication such as the possibility of bowel injury with lateral (beach chair) approach should be acknowledged. Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have rewritten this part. Avoid vague statements like "Although some people think" and "this phenomena may be ignored by many researchers". Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have revised it. The terminology "skew out" has been used multiple times. Please be use a more specific term or explain. Again the use of term "excellent technical choice" in conclusions is aggressive. Please modify Answer: Thanks very much for reviewer’s comment. It`s a very good advice. We have revised it. The manuscript needs significant language and grammar editing Answer: Thanks very much for reviewer’s comment. We have sent our manuscript to The AJE Company and got their premiums editing service. Thanks for opportunity to review Gianluca Cappelleri (Reviewer 2): Please include all comments for the authors in this box rather than uploading your report as an attachment. Please only upload as attachments annotated versions of manuscripts, graphs, supporting materials or other aspects of your report which cannot be included in a text format. Please overwrite this text when adding your comments to the authors. The manuscript is overall improved, although some concerns remains. The main trouble is its presentation. English was not revised. An English speaker is mandatory for grammar, syntax and sentence building. By now is very difficult to follow