Reliability and Validity of Plantar Pressures and the Modified ICPBL Test vs. Telemetry for Diagnosing Anatomical Discrepancies: A Pilot Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript addresses an interesting and clinically relevant problem related to the diagnosis of anatomical lower limb length discrepancy by comparing two clinical methods—the modified ICPBL test and plantar pressure analysis—with the radiographic reference method, telemetry. The topic is important in the fields of physiotherapy, podiatry, and biomechanics because it relates to the possibility of reducing patients’ exposure to X-ray radiation.

Despite the interesting topic and potential clinical value, the manuscript requires substantial methodological, statistical, and editorial revisions. The main concerns relate to the very small sample size, insufficient justification of statistical inferences, methodological ambiguities, and overly strong interpretations of the results.

Major Methodological Issues

Very small sample size
The study includes only a limited number of participants divided into groups with and without anatomical discrepancy.

This represents a very small sample size for a diagnostic accuracy study, particularly considering the analyses performed, including ROC analysis, sensitivity and specificity calculations, intraclass correlation coefficients, and Bland–Altman analysis.

The result indicating perfect diagnostic accuracy for the ICPBL test with such a small sample is statistically questionable and may reflect overfitting, sampling bias, or random alignment of the data.

What should be improved
The authors should explicitly acknowledge the risk of overestimation of diagnostic accuracy in the discussion section and avoid categorical statements about perfect accuracy. Ideally, future research should include a substantially larger sample.

Problem with the study design description
The authors describe the study as a prospective diagnostic validation pilot study with a cohort design. However, the structure of the investigation corresponds more closely to a cross-sectional diagnostic accuracy study rather than a cohort study.

What should be improved
The study design should be described as a cross-sectional diagnostic accuracy pilot study and should refer to STARD guidelines for reporting diagnostic studies.

Unclear sampling procedure
The manuscript suggests that random sampling was used, yet the description indicates that participants were recruited from a private clinic and from volunteers suspected of having limb length discrepancy.

This recruitment strategy corresponds more closely to convenience sampling rather than true random sampling.

What should be improved
The authors should clearly state that the sample represents a convenience sample and not a randomly selected population.

Diagnostic threshold
The authors use a very small threshold to define anatomical discrepancy, which remains controversial in the literature.

In most clinical studies larger discrepancies are usually considered clinically meaningful. The manuscript itself acknowledges that biomechanical consequences are typically observed only at greater differences between limbs.

What should be improved
The manuscript should clearly distinguish between a diagnostic detection threshold and clinically meaningful discrepancy and should provide a stronger justification for the selected threshold.

Statistical Issues

Perfect diagnostic accuracy
The reported result showing perfect diagnostic discrimination for the modified ICPBL test is extremely unusual in clinical research.

Such perfect performance in small samples frequently reflects statistical artifacts or sampling bias.

What should be improved
The discussion should clearly state that the observed perfect discrimination should be interpreted cautiously due to the limited sample and potential sampling bias.

Lack of statistical power analysis
The authors refer to previous literature to justify the sample size but do not conduct a formal power analysis for diagnostic accuracy or ROC analysis.

What should be improved
A statistical power calculation should be included to demonstrate that the sample size is sufficient to detect meaningful diagnostic differences.

Intraclass correlation coefficient reporting
The manuscript reports intraclass correlation coefficients for the measurement techniques and intra-examiner reliability. However, the specific ICC model used is not reported.

What should be improved
The authors should specify the statistical model used for the ICC analysis and clearly describe the assumptions underlying the reliability assessment.

Interpretation Issues

Overly strong conclusions
The manuscript states that the modified ICPBL test demonstrates perfect discrimination. This statement is too categorical, particularly in the context of a pilot study with a limited sample size.

What should be improved
A more cautious interpretation would state that the modified ICPBL test showed very high diagnostic accuracy within the studied sample.

Overstated claim regarding replacement of radiographic evaluation
The manuscript suggests that the method could replace radiographic telemetry. Such a claim is not supported by the presented data.

What should be improved
The authors should instead propose the method as a potential screening or preliminary assessment tool rather than a replacement for radiographic diagnosis.

Structural Issues

Introduction
The introduction is somewhat lengthy and includes repeated explanations and definitions.

What should be improved
The section should be shortened and more clearly focused on the research gap addressed by the study.

Methods section
Several methodological details remain insufficiently described, including aspects related to measurement calibration and the reliability characteristics of the pressure measurement platform.

What should be improved
The methods section should provide a clearer and more detailed description of measurement procedures and technical validation.

Discussion
The discussion tends to emphasize the strengths of the findings while providing limited critical reflection on the limitations of the study.

What should be improved
The discussion should include a more balanced evaluation of the study’s methodological limitations and the potential impact of bias.

Language and Style Issues

The manuscript contains several language and stylistic problems, including grammatical inaccuracies, awkward sentence construction, and punctuation issues.

Professional language editing by a native English speaker is recommended to improve clarity and readability.

Technical Issues

Units of measurement
The manuscript reports plantar pressure using units that are uncommon in most plantar pressure platforms. Most systems report pressure values using different units.

What should be improved
The units of measurement should be standardized and consistent with commonly used biomechanical reporting standards.

Tables
Some tables are unnecessarily complex and difficult to interpret.

What should be improved
The tables should be simplified to improve clarity and readability.

Specific Recommendations for Revision

Methodology
The description of the study design should be revised, the sampling procedure clarified, and the diagnostic threshold more carefully justified.

Statistics
The manuscript should include statistical power analysis, specify the ICC model used, and interpret diagnostic accuracy results more cautiously.

Results
Redundant textual descriptions of the tables should be reduced and the presentation of results streamlined.

Discussion
The conclusions should be moderated and the section discussing study limitations expanded.

Language
A thorough professional language revision is recommended to correct grammatical and stylistic issues.

Final Evaluation

The scientific quality of the manuscript can be considered moderate.

The strengths of the study include the clinical relevance of the topic, the attempt to validate a practical clinical diagnostic method, and the use of several statistical techniques commonly applied in diagnostic research.

The main weaknesses include the small sample size, the overinterpretation of diagnostic accuracy, and several methodological ambiguities.

Comments on the Quality of English Language

The manuscript contains several language and stylistic problems, including grammatical inaccuracies, awkward sentence construction, and punctuation issues.

Author Response

We want to thank you for the opportunity we offer to review our document. We hope that you will find the current version informative to your readership and acceptable for publication. Thanks for your review commentaries to improve the quality of the manuscript. A deep and substantial modification has been carried out according to your suggestions.

            Modifications and corrections are indicated by line numbers in the 'Main Document'. Additionally, we have highlighted the changes within the text using a yellow marker tool.

Thank you for your feedback and suggestions to improve the quality of our manuscript. We have made substantial and thorough revisions in accordance with your recommendations.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript evaluates the reliability and validity of two non-radiological diagnostic methods—modified ICPBL testing and plantar pressure analysis—for detecting anatomical lower limb discrepancy, using telemetry as the gold standard reference method. The topic is clinically relevant because limb length discrepancy is frequently encountered in musculoskeletal practice, and reliable non-radiographic screening tools could reduce radiation exposure and facilitate clinical assessment. The study attempts to provide diagnostic accuracy metrics including ROC analysis, intraclass correlation coefficients, and predictive values, which are appropriate for this type of validation research. Overall, the manuscript addresses an interesting research question and provides potentially valuable data; however, several methodological, statistical, and reporting issues need clarification before the results can be considered robust and clinically generalizable.

 

The abstract summarizes the objectives, methods, and principal findings of the study and generally captures the essence of the manuscript. However, several aspects should be improved. The description of the study design is somewhat confusing, as it refers to a “prospective, single-gate cohort design analytical cross-sectional diagnostic validation pilot study.” These terms overlap and should be simplified to clearly indicate that this is a diagnostic accuracy pilot study. In addition, the abstract reports extremely high diagnostic performance for the modified ICPBL test (AUC = 1.0 with 100% sensitivity and specificity), which should immediately be contextualized with the small sample size to avoid overinterpretation. The wording should also be revised for clarity and grammar.

 

The introduction provides a reasonable overview of limb length discrepancy terminology and explains the distinction between anatomical and functional discrepancies. The authors appropriately describe telemetry as the gold standard diagnostic method and justify the need for alternative non-radiographic tools. However, the literature review could be improved by including more recent and clinically oriented studies on limb length discrepancy assessment, particularly within orthopedics and biomechanics. In addition, the rationale for directly comparing ICPBL with plantar pressure analysis is not fully developed. While both methods are mentioned as clinical tools, the introduction would benefit from a clearer explanation of why plantar pressure measurements might theoretically reflect anatomical discrepancy and how this mechanism compares with pelvic leveling techniques. Some sentences also contain grammatical errors and inconsistent terminology that should be corrected.

 

The methods section contains several strengths, including ethical approval, defined inclusion and exclusion criteria, and a description of measurement protocols. The use of telemetry as a reference standard is appropriate for evaluating diagnostic validity. Nevertheless, several methodological concerns remain. First, the sample size is very small (30 subjects, with only 13 in the discrepancy group), which severely limits the statistical power and reliability of diagnostic accuracy estimates. While the authors justify this as a pilot study, they also report extremely precise diagnostic parameters that may reflect overfitting rather than true diagnostic performance. Second, the recruitment process needs clearer explanation. According to the flow chart, 58 subjects were screened but only 30 were included, and the reasons for exclusion are not fully detailed. Third, all measurements were performed by a single examiner, which prevents assessment of inter-examiner reliability and limits generalizability. Fourth, the study uses a threshold of 3 mm to define anatomical discrepancy. While the authors justify this based on measurement precision, most orthopedic literature considers discrepancies below 5–10 mm clinically insignificant. The clinical rationale for this threshold should therefore be more clearly justified. Finally, the statistical methodology is generally appropriate, but the description could be clarified. ROC analysis, ICC calculation, and Bland-Altman agreement analysis are appropriate for diagnostic validation studies, although the interpretation of these results should be more cautious.

 

The results section presents descriptive statistics, ROC curves, and reliability metrics comparing the two methods with telemetry. The data demonstrate statistically significant differences between subjects with and without anatomical discrepancy. According to Table 1, subjects with discrepancy showed a mean difference of 8.09 ± 3.24 mm on telemetry compared with 0.41 mm in controls, and similar patterns were observed for the ICPBL test and plantar pressure measurements  . The ROC analysis reported an AUC of 0.783 for plantar pressures and 1.000 for the modified ICPBL test  . While these findings suggest good diagnostic performance, the perfect discrimination reported for ICPBL is statistically suspicious in such a small sample. Perfect sensitivity and specificity often indicate overfitting or insufficient variability in the dataset. This should be interpreted with caution and discussed more explicitly as a limitation. Additionally, the confidence intervals around several estimates are wide, which reflects uncertainty in the results. The authors should also clarify whether normality assumptions were met before applying parametric tests.

 

The discussion appropriately compares the results with previous studies on manual methods for assessing limb length discrepancy. The authors correctly acknowledge that manual palpation techniques have historically shown variable reliability and that examiner experience may influence results. The discussion also highlights differences between simulated discrepancies used in many plantar pressure studies and real anatomical discrepancies, which is an important point. However, some conclusions appear overly strong. The statement that the modified ICPBL test demonstrates perfect diagnostic accuracy is not justified given the limited sample size and lack of inter-examiner validation. The discussion should therefore emphasize that these results are preliminary and exploratory. Furthermore, the authors could strengthen the discussion by addressing potential biomechanical mechanisms linking plantar pressure asymmetry to limb length discrepancy and by comparing their findings with imaging-based studies from orthopedic literature.

 

The limitations section identifies several relevant weaknesses, including the small sample size and lack of inter-examiner reliability analysis. These limitations are important and should be emphasized more strongly in the interpretation of the results. Additional limitations should also be acknowledged, such as possible selection bias from recruiting participants at a specialized clinic and the limited external validity of the findings. Moreover, plantar pressure analysis was performed only in static conditions, whereas gait analysis could provide more clinically relevant information.

 

The figures and tables are generally useful and help illustrate the statistical analyses. The ROC curves and Bland-Altman plots are appropriate for visualizing diagnostic performance and agreement between methods. However, the quality and labeling of some figures should be improved. For example, Figure 2 presents the ROC curves but does not clearly distinguish the reference line from the two test curves, and Figure 3 could benefit from clearer axis labels and explanations of the limits of agreement. Tables summarizing ICC values, sensitivity, specificity, and predictive values are informative but should be reformatted for clarity.

 

The reference list includes several relevant sources but relies heavily on older literature from the 1970s and 1980s. While these studies are historically important, the manuscript would benefit from additional contemporary references, particularly systematic reviews and recent biomechanical studies on limb length discrepancy and gait analysis.

 

In conclusion, the manuscript addresses an interesting and clinically relevant topic and provides preliminary data suggesting that the modified ICPBL test and plantar pressure analysis may have diagnostic value in detecting anatomical limb length discrepancy. However, the extremely small sample size, absence of inter-examiner reliability testing, and surprisingly perfect diagnostic performance reported for the ICPBL test raise concerns regarding the robustness of the findings. Substantial revisions are required to clarify the methodology, moderate the interpretation of results, and improve the clarity and quality of the manuscript. With these improvements and additional validation in larger cohorts, the study could contribute valuable information to the field of clinical assessment of limb length discrepancy

Author Response

We want to thank you for the opportunity we offer to review our document. We hope that you will find the current version informative to your readership and acceptable for publication. Thanks for your review commentaries to improve the quality of the manuscript. A deep and substantial modification has been carried out according to your suggestions.

Modifications and corrections are indicated by line numbers in the 'Main Document'. Additionally, we have highlighted the changes within the text using a yellow marker tool.

 

Thank you for your feedback and suggestions to improve the quality of our manuscript. We have made substantial and thorough revisions in accordance with your recommendations.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors Review report for “Reliability and Validity of Plantar Pressures and the Modified ICPBL Test vs. Telemetry for Diagnosing Anatomical Discrepancies” First of all, the reviewer would like to thank the editors for giving me the opportunity to participate in this review process.   Comment to the Authors:   Although it seems that the present study was implemented carefully, the paper was difficult to understand. The manuscript would benefit from significant and substantial language revision for clarity and precision. However, the main issue is not grammar alone. The writing currently mixes background, methods, results, and interpretation within the same sentences, which makes the study difficult to follow. Please revise the manuscript by simplifying sentence structure, reducing redundancy, and aligning the wording more closely with the actual study design and statistical results.     Major concerns: The statistical analysis requires the statistician's revision.   Use shorter sentences and assign one function to each sentence.   Too many terminologies make it difficult for readers to follow the description: like lower limb discrepancies, Di, DA, DF, real asymmetry, true discrepancy, postural discrepancy, apparent discrepancy, and anatomical discrepancy.   In addition, too many abbreviations also hinder the reader's understanding. Simplify and standardize terminology throughout the manuscript.   The expression is too strong throughout, despite a pilot study. Please moderate statements of certainty. Given the pilot nature and small sample size, the conclusions should be phrased more cautiously. Comments on the Quality of English Language

Use shorter sentences and assign one function to each sentence.

Simplify and standardize terminology throughout the manuscript.

Moderate overly strong claims, especially given the pilot design and small sample size.

Author Response

We want to thank you for the opportunity we offer to review our document. We hope that you will find the current version informative to your readership and acceptable for publication. Thanks for your review commentaries to improve the quality of the manuscript. A deep and substantial modification has been carried out according to your suggestions.

Modifications and corrections are indicated by line numbers in the 'Main Document'. Additionally, we have highlighted the changes within the text using a yellow marker tool.

Thank you for your feedback and suggestions to improve the quality of our manuscript. We have made substantial and thorough revisions in accordance with your recommendations.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Accept in present form

Author Response

Thank you very much for your valuable feedback in improving the present research.

Reviewer 3 Report

Comments and Suggestions for Authors

The reviewer considers that the quality of the current revision has significantly improved. The reviewer considers that there are a few points that require revision or clarification.

At line 23, please spell out ICPBL.
In the Introduction part, the theoretical background and hypothesis seem redundantly described. Please consider modifying them to improve the readability.
“3 mm were classified into form the group with the condition DA,” (line 29) “form” may be unnecessary.
“Kg” in line 36 should be “kg/cm²”? Please make sure some of “2” in “cm²” should be superscripted.

Author Response

Thank you very much for your final valuable considerations to improve the present research. We have followed your instructions as follows:

At line 23, please spell out ICPBL..- ok; done : Iliac Crests Palpation and Pelvimeter with Blocks test (ICPBL)

In the Introduction part, the theoretical background and hypothesis seem redundantly described. Please consider modifying them to improve the readability. .- thank you very much; we have improved this section: Several methods have been proposed to assess lower limb-length discrepancies; however, none have demonstrated sufficient reliability and validity for diagnosing anatomical discrepancies (DA). Objectives: This study primarily aims to evaluate the accuracy of two traditional tests—the Modified Iliac Crests Palpation and Pelvimeter with Blocks test (ICPBL) and plantar pressure analysis—by comparing them with the gold standard telemetry (TE) method for diagnosing DA. The secondary objective is to assess the intra-rater reliability of these two tests and determine their potential applicability in clinical settings.

“3 mm were classified into form the group with the condition DA,” (line 29) “form” may be unnecessary.; ok, deleted.

“Kg” in line 36 should be “kg/cm²”? Please make sure some of “2” in “cm²” should be superscripted. Yes. Thank you very much. Done. .- 2.28 ± 1.77 kg/cm²