Additional Erythrocyte Field Is Helpful for Graphic Type Differentiation of Cell Count Determination Between Acute Periprosthetic Joint Infection and Hematoma

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper "Additional erythrocyte field is helpful etc...) by Florian Hubert Sax et al. is interesting and well performed and demonstrated that this grafical type differentiation may be useful in the diagnosis of acute periprosthetic joint infections.

I have no particular objectives to notice. 

Only one objective that is reported in the abstract and repeated in the first line of Results.

In the abstract, line 25 you wrote "43 patients underwent revision ...", than at line 28 reported that "32 pts (29,6%) were classified". 32/43 is non 29,6%, 32/108 is 29,6%, where 108 are the sum of 77 total knee arthoplasties and 31 hip arthroplasties. I think that would be better write 32 cases or total arthroplasties (hip and knee) not patients.

The same objective at line 11 of Results.

Author Response

Reviewer 1:

 

The paper "Additional erythrocyte field is helpful etc...) by Florian Hubert Sax et al. is interesting and well performed and demonstrated that this grafical type differentiation may be useful in the diagnosis of acute periprosthetic joint infections.

I have no particular objectives to notice. 

Only one objective that is reported in the abstract and repeated in the first line of Results.

In the abstract, line 25 you wrote "43 patients underwent revision ...", than at line 28 reported that "32 pts (29,6%) were classified". 32/43 is non 29,6%, 32/108 is 29,6%, where 108 are the sum of 77 total knee arthoplasties and 31 hip arthroplasties. I think that would be better write 32 cases or total arthroplasties (hip and knee) not patients.

The same objective at line 11 of Results.

 

Answer: Thank you for your advice. We corrected the objective and wrote cases instead of patients and highlighted it in our paper.

Reviewer 2 Report

Comments and Suggestions for Authors

It is recommended to improve the visual quality of Figures 2 to 5 (resolution, contrast, and axis legibility). They appear pixelated, and if possible, a comparison with Figure 1 would provide a frame of reference for more precise identification of cell fields and the visual differences between types II, IV, V, and VI for clinical identification.

Table 1 adequately displays the classic diagnostic parameters (sensitivity, specificity, predictive values, and likelihood ratios). It is suggested that these values ​​be more explicitly integrated into the Discussion, particularly when compared with the LMNE graphical interpretation. Furthermore, their clinical applications or relevance should be mentioned, as in the case of the high LR+ (73.62) and the very low LR− (0.03).
In the section discussing the limitations of cell count, PMN, and CRP (approximately lines 208–215), the manuscript adequately acknowledges the low sensitivity of these markers. However, further exploration of how these findings should be interpreted in clinical practice, particularly in patients with postoperative hematoma and elevated counts, is recommended.

It is suggested that an exploratory analysis stratified by sex be considered, comparing: Cell Count, Percentage of PMNs, and LMNE Type Distribution. Given the good distribution among the study subjects, it could provide additional information on relevant biological or inflammatory differences and strengthen the depth of the work.

Author Response

Reviewer 2:

It is recommended to improve the visual quality of Figures 2 to 5 (resolution, contrast, and axis legibility). They appear pixelated, and if possible, a comparison with Figure 1 would provide a frame of reference for more precise identification of cell fields and the visual differences between types II, IV, V, and VI for clinical identification.

Answer: We thank the reviewer for this valuable and constructive comment regarding the visual quality of Figures 2–5. Unfortunately, an improvement of the image resolution, contrast, or axis legibility is not possible. The images were generated by a legacy device that produces output exclusively in printed (paper) format. These printouts were subsequently scanned and digitally archived, and no original digital image files with higher resolution are available. Therefore, we do not have access to higher-quality source images that would allow further optimization. While we acknowledge that a direct visual comparison with Figure 1 would be helpful for clinical identification, the aforementioned technical limitations prevent us from providing improved or alternative versions of these figures. We appreciate the reviewer’s understanding of these constraints.

 

Table 1 adequately displays the classic diagnostic parameters (sensitivity, specificity, predictive values, and likelihood ratios). It is suggested that these values ​​be more explicitly integrated into the Discussion, particularly when compared with the LMNE graphical interpretation. Furthermore, their clinical applications or relevance should be mentioned, as in the case of the high LR+ (73.62) and the very low LR− (0.03).

Answer: We thank the reviewer for this valuable comment. This aspect has been discussed in greater detail in the revised manuscript (line 203 ff.).

 

In the section discussing the limitations of cell count, PMN, and CRP (approximately lines 208–215), the manuscript adequately acknowledges the low sensitivity of these markers. However, further exploration of how these findings should be interpreted in clinical practice, particularly in patients with postoperative hematoma and elevated counts, is recommended.

Answer: We thank the reviewer for this valuable comment. We added a more in-depth interpretation and the clinical relevance in the revised manuscript (line 217 ff and 223).

 

It is suggested that an exploratory analysis stratified by sex be considered, comparing: Cell Count, Percentage of PMNs, and LMNE Type Distribution. Given the good distribution among the study subjects, it could provide additional information on relevant biological or inflammatory differences and strengthen the depth of the work.

Answer: We thank the reviewer for this helpful suggestion. An addition exploratory analysis stratified by sex was performed. No statistically significant differences were observed between female and male subjects for cell count percentage of PMNs, or LMNE type distribution, or other diagnostic parameters. These results have been added to the manuscript (line 180 ff).

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Based on the observations made, I inform you

Integration of diagnostic values and clinical interpretation (Table 1). The Discussion has been substantially improved. The authors now clearly explain the clinical implications of sensitivity, specificity, and likelihood ratios, particularly emphasizing the limited value of classical markers (cell count, PMN percentage, CRP) for ruling out early postoperative infection. The added interpretation of likelihood ratios strengthens the translational relevance of the study.

The limitations of conventional cut-offs (cell count ≥10,000/µL, PMN percentage, and CRP thresholds) are now explicitly discussed in a clinically meaningful manner. The manuscript clearly states that these parameters should not be used as standalone diagnostic tools in early postoperative settings, which appropriately supports the rationale for the LMNE approach.

The authors have addressed this point by reporting that no statistically significant differences were observed between sexes for any diagnostic parameter. Although presented concisely, this statement adequately responds to the reviewer’s suggestion.

The figures remain clinically illustrative and consistent with the text. While a more explicit comparative description with Figure 1 could further enhance didactic clarity, this aspect does not affect the validity of the results or the conclusions. Overall, this point has been partially addressed and does not warrant further revision.