Longitudinal Changes in Kinesiophobia, Psychological Readiness, and Knee Function Across Anterior Cruciate Ligament Reconstruction Rehabilitation Phases

General Comments

Reviewer comment

Authors' response

Overall, the study has some merits, but there are also disadvantages, such as the relatively small sample size, the M:F imbalance, and the retrospective nature of the investigation. Given study limitations, the generalizability of the findings of the present study may be limited.

We appreciate this balanced assessment. These limitations are now explicitly acknowledged in the revised manuscript. The moderate sample size has been added as an explicit limitation in Section 4.6 (Limitations), and the retrospective design and M:F imbalance were already noted. The Conclusions section has been revised to soften strong statements and reflect these limitations throughout.

Introduction

Reviewer comment

Authors' response

Comment 1: The introduction could be shortened and should be made more impactful, avoid to discuss previous findings as you would do in a discussion section. Also I do strongly suggest to avoid the use of subheadings in the introduction section, consider subdivision into paragraphs instead.

Thank you for this suggestion. We agree. The introduction has been substantially revised: (1) the theoretical models paragraph has been condensed from four sentences to a single concise sentence; (2) all subheadings (1.1 Research Gap, 1.2 Objective, 1.3 Hypotheses) have been removed and the content reorganized into flowing paragraphs; (3) discussion-style elaboration has been removed throughout. The three hypotheses have been merged into a single sentence. Please see the revised Introduction section.

Comment 2: Consider adding updated reference to support the statement on re-injury risk following ACL surgery and on RTS in amateur athletes (e.g. Fältström et al., BMC Sports Sci Med Rehabil. 2024;16(1):131; Legnani et al., J Sports Med Phys Fitness. 2019;59(11):1902-1907).

We thank the reviewer for these suggestions. Both references have been added. The following sentence has been inserted in the Introduction: 'Re-injury risk and long-term RTS outcomes remain a significant concern, particularly among amateur athletes [18,19].' References 18 (Fältström et al., 2024) and 19 (Legnani et al., 2019) have been added to the reference list.

Comment 3: Consider mentioning this systematic review when introducing variables affecting return to sport: Preoperative predictors for return to physical activity following anterior cruciate ligament reconstruction (ACLR): a systematic review. BMC Musculoskelet Disord. 2023;24(1):471.

Thank you. This systematic review has been incorporated. The following sentence has been added in the Research Gap paragraph: 'Preoperative psychological factors have also been identified as modifiable predictors of return to physical activity following ACLR [22].' Reference 22 (Carter et al., 2023) has been added to the reference list.

Methods

Reviewer comment

Authors' response

Comment 4: This section should be reworked and readability improved.

The Methods section has been substantially revised for readability and clarity. All subsections have been reviewed and rewritten where necessary, including improved sentence structure, clearer transitions, and more explicit methodological justifications throughout.

Comment 5: 'Physically active individuals and recreational athletes' is quite vague and could be better clarified.

Agreed. The description has been clarified. The sentence now reads: 'The clinic primarily manages post-operative rehabilitation for physically active individuals and recreational athletes (defined as persons engaging in structured physical activity or organized sport at least twice weekly, independent of competitive level).' Please see Section 2.1.

Comment 6: Inclusion/exclusion criteria should be clarified much better: any BMI limit?, age limit? What about concomitant meniscal pathology requiring/not requiring treatment? Were patients excluded if they had concomitant illnesses that might have affected their capacity to be physically active at follow-up? What about graft choice? Extra articular procedures (e.g. lateral tenodeses)?

Thank you for this important comment. Section 2.2 has been revised to address each point explicitly: (1) Age: 'aged 18 years or older, with no upper age limit applied'; (2) BMI: 'No BMI limit was applied; BMI was recorded as a demographic variable only'; (3) Meniscal pathology: added to exclusion criteria — 'concomitant meniscal pathology requiring surgical treatment'; (4) Graft choice: 'isolated ACLR regardless of graft type'; (5) Concomitant illness: patients with concomitant knee surgical procedures other than isolated ACLR were excluded; (6) Extra-articular procedures: these were captured under the exclusion criterion of 'concomitant knee surgical procedures other than isolated ACLR.' Please see the revised Section 2.2.

Comment 7: What about time between injury and surgery as a variable affecting RTS? How were key variables selected?

We acknowledge that time between injury and surgery is a recognized variable in ACL rehabilitation research. In this retrospective study, time from injury to surgery was not systematically recorded in the clinic's electronic records and therefore could not be included as a variable. This represents an acknowledged limitation of the retrospective design, which is noted in Section 4.6. Variable selection was guided by the study's primary objective of mapping phase-specific psychological and functional trajectories using validated, routinely collected patient-reported outcome measures.

Comment 8: Who did perform surgeries? One surgeon? How experienced? How was one technique chosen instead of another? What about surgical technique? Were the authors involved in the surgical treatment/rehabilitation?

All surgical procedures were performed by board-certified orthopedic surgeons with subspecialty training in knee ligament surgery. As this was a retrospective study at a rehabilitation center receiving referrals from multiple surgeons, individual surgeon identity was not recorded in the rehabilitation records and is not a variable of interest in this study, which focuses on rehabilitation outcomes rather than surgical factors. Graft type was surgeon-dependent; however, current evidence from a network meta-analysis of 45 trials (n = 3,992) indicates no significant differences in patient-reported functional outcomes across common autograft options (Mo et al., 2020), supporting the validity of pooling participants across graft types. Regarding author involvement: 'None of the authors were involved in the surgical treatment or rehabilitation delivery of the included patients; data were extracted retrospectively from existing clinical records.' This statement has been added to Section 2.4.

Comment 9: Were only time-based criteria used to allow patients to be cleared to RTS (What about sport specific? According to test batteries?)

This is an important clarification. RTS clearance was not time-based only. The clinic employs a structured criteria-based protocol. The relevant section (2.1) now states: 'Although time windows defined phase boundaries, progression was criteria-based; patients advanced only upon meeting objective thresholds including pain levels, range of motion, limb symmetry indices, strength, and functional performance, per the clinic's structured ACLR protocol.' Phase Four RTS clearance specifically required ACL-RSI ≥70-75, TSK-17 ≤37, IKDC ≥80-85, hop battery ≥90% LSI, isokinetic strength ≥90% LSI, and agility measures. The full protocol has been provided as Supplementary Material S1.

Results

Reviewer comment

Authors' response

Comment 10: This section would benefit from restructuring for clarity.

The Results section has been revised for improved clarity and logical flow. Section 3.1 now reports n alongside all percentages, uses one decimal place throughout, and presents participant characteristics in a reorganized Table 1 (continuous variables first, followed by categorical variables).

Comment 11: Was any patient excluded from the original study group? Lost at follow-up?

Thank you for raising this. The screening and inclusion process is now fully reported. A total of 575 patient records were initially reviewed. Of these, 412 had assessments at only two time points and were excluded, 118 had assessments at three time points and were excluded, and the first 45 consecutive records with complete four-phase data were included. This is reported in Section 2.1 and illustrated in Figure 1 (flow diagram), which has been added to the revised manuscript.

Comment 12: Consider allowing one decimal only.

Agreed. One decimal place has been applied throughout the text and all descriptive tables, including Table 1 (Section 3.1 text), Table 2, and Table 3. Two decimal places have been retained in Table 4 to preserve statistical precision for mean differences, confidence intervals, and effect sizes, in accordance with standard reporting practice for inferential statistics.

Comment 13: Report number of patients together with percentages.

Agreed. All percentages in Section 3.1 now include the corresponding n. For example: 'mostly of males (n = 37, 82.2%)', 'left knee (n = 31, 68.9%)', 'Hamstring autograft (n = 21, 46.7%)', etc. Please see the revised Section 3.1.

Comment 14: Add p-value.

P-values are reported for all pairwise comparisons in Table 4 (Bonferroni-adjusted). The linear mixed model main effects with F-statistics and p-values are reported in Table 3 and referenced in Section 3.3. All p < 0.001 unless otherwise specified (Phase 3 vs Phase 4 TSK-17: p = 0.193).

Discussion

Reviewer comment

Authors' response

Comment 15: Consider revising the section and avoiding repetition. Please highlight clinical relevance.

The Discussion section has been thoroughly revised to reduce repetition and enhance clinical relevance. Redundant restatements of results have been removed. Clinical implications are highlighted in Section 4.5, which now includes an expanded discussion of the temporal dissociation between kinesiophobia and readiness, with specific recommendations for exposure-based therapy and mastery-oriented tasks during mid-to-late rehabilitation.

Comment 16: Please start your discussion section by reporting the most important findings of your study and avoiding focusing on background or study purposes in the first statement.

Agreed. The opening paragraph of the Discussion has been rewritten to lead with the key findings: 'Psychological and functional recovery following ACLR were found to follow distinct temporal trajectories rather than improving synchronously across rehabilitation phases. Kinesiophobia declined most markedly during mid-rehabilitation, psychological readiness increased progressively across all phases, and peak improvements in knee function occurred during late rehabilitation.' Please see the revised Section 4.

Comment 17: Please use passive voice throughout the text.

Passive voice has been applied throughout the revised Discussion. Active constructions such as 'These findings refine...' and 'These findings extend...' have been revised to 'The existing cross-sectional literature is refined by these findings...' and 'Existing theoretical models are extended by these findings...' Please see the revised Sections 4.1 and 4.4.

Comment 18: The concepts of psychological readiness related to return to sports and its relationship to functional performance tests could be expanded a little bit to discuss some recent studies related to this issue (e.g. Aizawa et al., BMC Sports Sci Med Rehabil. 2022;14(1):97; Legnani et al., J Clin Med. 2023;12(2):626).

Thank you for these recommendations. Both studies have been incorporated in Section 4.2 (Psychological Readiness). The following sentence has been added: 'This finding is consistent with cross-sectional evidence demonstrating associations between physical function and psychological readiness following ACLR [34], and with research linking jumping performance to psychological readiness at six months post-surgery [35].' References 34 (Aizawa et al., 2022) and 35 (Legnani et al., 2023) have been added.

Conclusions

Reviewer comment

Authors' response

Comment 19: Given study limitations, I would avoid strong statements. This paragraph should be shortened as it should only contain the most relevant results of the investigation. Avoid speculative sentences.

Agreed. The Conclusions section has been revised accordingly: (1) 'demonstrates' has been replaced with 'provides evidence that' to reflect the observational design; (2) a speculative sentence about management effects has been replaced with: 'Early identification of kinesiophobia and psychological readiness using phase-specific assessment may inform targeted clinical decision-making during rehabilitation'; (3) the third paragraph has been shortened and the final sentence now explicitly acknowledges study limitations: 'Conclusions should be interpreted in light of the retrospective design, moderate sample size, unequally spaced phase intervals, and complete-case analytic approach.'

References

Reviewer comment

Authors' response

Comment 20: Please provide updated references (see suggestions above).

All references suggested by the reviewer have been added: (1) Fältström et al., BMC Sports Sci Med Rehabil. 2024 [Ref 18]; (2) Legnani et al., J Sports Med Phys Fitness. 2019 [Ref 19]; (3) Carter et al., BMC Musculoskelet Disord. 2023 [Ref 22]; (4) Aizawa et al., BMC Sports Sci Med Rehabil. 2022 [Ref 34]; (5) Legnani et al., J Clin Med. 2023 [Ref 35]. The reference list has been updated and renumbered accordingly.

Tables

Reviewer comment

Authors' response

Comment 21: Table 1: rework for clarity. Consider leaving BMI and deleting weight and height. Clarify abbreviation of BMI under the table. Consider allowing one decimal only.

Table 1 has been fully revised: (1) Height and weight have been removed as suggested; (2) The table has been reorganized with continuous variables (Age, BMI) presented first, followed by categorical variables; (3) BMI has been defined in the table note: 'BMI: body mass index (kg/m²)'; (4) One decimal place has been applied throughout. Please see the revised Table 1.

Figures

Reviewer comment

Authors' response

Comment 22: Figure 4: Clarify abbreviations under the figure.

The abbreviations have been added to the figure caption (now Figure 5 following renumbering due to the addition of the flow diagram as Figure 1). The caption now includes: 'TSK-17: Tampa Scale of Kinesiophobia (17-item); ACL-RSI: Anterior Cruciate Ligament–Return to Sport after Injury scale; IKDC: International Knee Documentation Committee subjective knee form; ACLR: anterior cruciate ligament reconstruction.' Please see the revised Figure 5 caption.

General Comments

Reviewer comment

Authors' response

This manuscript investigates phase-specific changes in kinesiophobia, psychological readiness, and patient-reported knee function during rehabilitation after ACL reconstruction (ACLR) using a retrospective longitudinal cohort design. The topic is clinically relevant and addresses an important gap in the literature. The manuscript is generally well-structured; however, several points require clarification or improvement.

We thank Reviewer 2 for this positive overall assessment and for the constructive and detailed comments that follow. We have addressed each point carefully as described below.

Introduction

Reviewer comment

Authors' response

Comment 1: The statement 'an estimated global incidence exceeding two million cases annually' may be difficult to verify, as ACL incidence is typically reported in population- or region-specific rates rather than global totals. Consider providing regional incidence data or citing large registry-based studies to support this claim.

We respectfully note that this figure is explicitly stated in the cited reference (Renström, 2013, Br J Sports Med), which reports in the abstract: 'Over two million anterior cruciate ligament (ACL) injuries occur worldwide annually.' As this estimate originates directly from the cited peer-reviewed source, we have retained the statement. No change to the manuscript was considered necessary for this item.

Comment 2: Statements regarding the influence of psychological factors on return to sport (RTS) would be strengthened by including specific data or meta-analytic evidence.

Agreed. The following sentence has been added to paragraph 3 of the Introduction: 'A systematic review by Nwachukwu et al. demonstrated that psychological factors account for a significant proportion of failure to return to play following ACLR, independent of physical recovery [10].' Reference 10 (Nwachukwu et al., 2019) was already in the reference list and has been repositioned to support this statement. Please see the revised Introduction.

Comment 3: The discussion of Arabic-speaking cohorts is interesting but abrupt. Please clarify why this population is particularly relevant and provide evidence on whether cultural context affects psychological outcomes or RTS after ACLR.

Thank you for this observation. The paragraph has been expanded to provide clearer justification. The revised text now reads: 'Moreover, most evidence originates from Western populations, with minimal representation of Arabic-speaking cohorts, despite the availability of validated Arabic versions of the TSK-17, ACL-RSI, and IKDC [23–25]. This gap is clinically meaningful, as formal psychological support is rarely integrated into rehabilitation pathways in Arabic-speaking healthcare contexts, making phase-specific psychological monitoring particularly relevant for this population. This limited representation restricts the development of contextually informed rehabilitation strategies and reduces broader applicability across diverse populations.' Please see the revised Research Gap paragraph.

Methodology

Reviewer comment

Authors' response

Comment 4: The study includes only patients with complete data across all four rehabilitation phases. However, the manuscript does not report how many patient records were initially screened. Including a flow diagram of inclusion and exclusion would improve transparency and clarify sampling and attrition.

Agreed. The screening and inclusion process is now fully reported in Section 2.1: 'A total of 575 patient records were initially reviewed. Of these, 412 had assessments at only two time points and were excluded, 118 had assessments at three time points and were excluded, and the first 45 consecutive records containing complete data across all four rehabilitation phases were included.' A CONSORT-style flow diagram has been added as Figure 1 in the revised manuscript.

Comment 5: Although the rehabilitation phases appear clinically reasonable, citing specific rehabilitation guidelines would strengthen their justification. Additionally, the manuscript lacks details on the rehabilitation program itself. Consider adding a short subsection describing the protocol structure, therapist supervision, and typical session frequency.

Thank you for this suggestion. The phase justification has been strengthened in Section 2.1, now explicitly stating that progression was criteria-based rather than purely time-driven, with specific objective thresholds for advancement. The full rehabilitation protocol, including phase-specific objectives and progression criteria, has been provided as Supplementary Material S1. A reference to this has been added: 'The full rehabilitation protocol, including phase-specific objectives and progression criteria, is provided as Supplementary Material S1.' Please see the revised Section 2.1.

Comment 6: The timing of assessments within each phase is unclear. Were assessments performed once per phase? Were they standardized to a specific week or visit? Clarification would enhance reproducibility.

This has been clarified in the revised Section 2.4: 'Assessments were conducted at each rehabilitation phase transition, corresponding to the point at which a patient met the criteria to progress to the next phase. Each patient contributed one assessment per phase, recorded at the clinical visit closest to the phase transition point. In cases where multiple visits occurred within a phase window, the assessment recorded at the phase transition visit was used. Phase Four assessments were conducted at the formal RTS clearance evaluation, typically at approximately nine months post-surgery.' Please see the revised Section 2.4.

Comment 7: To improve interpretation of clinical relevance, consider calculating standardized effect sizes (e.g., Cohen's d) for the observed changes.

Agreed. Cohen's d effect sizes have been calculated for all pairwise phase comparisons and added as a new column in Table 4. The following sentence has been added to Section 2.6: 'Standardized effect sizes (Cohen's d) were additionally calculated for each pairwise phase comparison to enhance interpretation of clinical relevance.' A summary statement has also been added to Section 3.3: 'Effect sizes were large to very large for most between-phase comparisons across all three outcomes (Table 4), with the exception of the Phase 3 to Phase 4 TSK-17 comparison, which yielded a small effect (d = 0.25), consistent with the non-significant finding and reflecting stabilization of kinesiophobia in late rehabilitation.' Please see the revised Table 4 and Section 3.3.

Results

Reviewer comment

Authors' response

Comment 8: Table 1 formatting is unclear; it is difficult to determine which categories correspond to which variables. Reorganizing the table, for example by presenting age, weight, height, and BMI first, followed by sex and other categorical variables, would improve readability. Also, define BMI in the table or legend.

Table 1 has been fully reorganized: continuous variables (Age and BMI) now appear first with their descriptive statistics, followed by all categorical variables. Height and weight have been removed as suggested by Reviewer 1. BMI has been defined in the table note: 'BMI: body mass index (kg/m²).' Please see the revised Table 1.

Comment 9: Figures 1–3 largely replicate data presented in Table 2. Consider moving them to supplementary material to illustrate individual-level distributions, rather than presenting them in the main manuscript. Note that standard deviations in figures appear to be automatically generated.

We respectfully retain Figures 1–3 (now renumbered Figures 2–4) in the main manuscript. These figures illustrate the longitudinal trajectories of the primary and secondary outcomes across rehabilitation phases and represent the core visual findings of the study. Although they present data also shown in Table 2, the figures serve a distinct purpose by enabling readers to visualize the temporal patterns of change. Individual score distributions are already presented in the Appendix (Figures A1–A3), which serve the supplementary purpose described by the reviewer.

Comment 10: In Section 3.3 (Linear Mixed Model Analysis), the sentence: 'Similarly, knee function (IKDC) demonstrated a significant effect of phase effect' should be corrected to 'effect of rehabilitation phase.'

Thank you for identifying this error. The sentence has been corrected to: 'Similarly, knee function (IKDC) demonstrated a significant effect of rehabilitation phase, with F(3,44) = 348.4 and p < 0.001.' Please see the revised Section 3.3.

Comment 11: In Table 3, the column labeled F (df1, df2) is unclear. Consider clarifying the degrees of freedom and presentation format.

Agreed. The Table 3 note has been updated to clarify: 'F: F-statistic; df1: numerator degrees of freedom; df2: denominator degrees of freedom, estimated using the Satterthwaite approximation within the linear mixed model framework.' Please see the revised Table 3 note.

Discussion

Reviewer comment

Authors' response

Comment 12: Some statements imply causal relationships that cannot be confirmed by a retrospective observational design. For example, statements suggesting that psychological adaptation facilitates functional recovery should be phrased more cautiously (e.g., 'may be associated with' rather than 'facilitates').

Agreed. Causal language has been softened throughout the Discussion. The phrase 'psychological adaptation may facilitates greater engagement' has been corrected and revised to 'psychological adaptation may be associated with greater engagement in demanding physical tasks required for late-stage functional improvements.' Additional causal language has been reviewed and revised throughout Section 4. Please see the revised Discussion.

Comment 13: An additional limitation to consider is the moderate sample size, which may limit statistical precision and generalizability.

Agreed. The following sentence has been added to Section 4.6 (Limitations): 'Additionally, the moderate sample size of 45 participants, while meeting the a priori power estimate, may limit statistical precision and the generalizability of findings to broader ACLR populations.' Please see the revised Section 4.6.

Conclusions

Reviewer comment

Authors' response

Comment 14: The conclusions are relevant and consistent with the results.

We thank the reviewer for this positive assessment. The Conclusions section has nevertheless been revised in response to Reviewer 1's comments to soften strong statements and remove speculative language, while retaining consistency with the results as noted.

References

Reviewer comment

Authors' response

Comment 15: Most references are older than ten years (20 out of 31), with only a few recent studies (two from 2022 and one from 2025). Updating the reference list with more current literature on ACL rehabilitation and psychological outcomes is recommended.

The reference list has been substantially updated. Five new references from 2022–2024 have been added, including: Fältström et al. (2024), Carter et al. (2023), Legnani et al. (2023), Aizawa et al. (2022), and Juweid et al. (2017). The reference list now includes a greater proportion of recent literature. The total reference count has increased from 31 to 38.

Comment 16: One reference is a thesis (Almalki, H., 2019). Consider replacing or supplementing with peer-reviewed journal articles where possible.

The thesis (Almalki, 2019) remains in the reference list as it represents the only Arabic-language adaptation of the TSK-17 specific to ACLR populations; no published peer-reviewed paper for this specific adaptation currently exists. However, as suggested, it has been supplemented with Juweid et al. (2017), a peer-reviewed psychometric validation of the Arabic TSK in Arabic-speaking patients with musculoskeletal pain (MYOPAIN, 2017;23(3-4):134-142). The citation now reads [23,27]. Please see the revised Section 2.3.

Comments and Responses

Reviewer comment

Authors' response

Comment 1: As this is a retrospective cohort study using real-world clinical data, the assessment timings in electronic medical records rarely align perfectly with strict chronological milestones. Please clarify how the 'predefined phases' (e.g., >1-3 months) were handled if a patient had multiple visits within that window, or if their assessment fell slightly outside the typical window. How was the precise assessment time point chosen for the analysis?

Thank you for raising this important methodological point. Section 2.4 has been revised to provide explicit clarification: 'Assessments were conducted at each rehabilitation phase transition, corresponding to the point at which a patient met the criteria to progress to the next phase. Each patient contributed one assessment per phase, recorded at the clinical visit closest to the phase transition point. In cases where multiple visits occurred within a phase window, the assessment recorded at the phase transition visit was used. Phase Four assessments were conducted at the formal RTS clearance evaluation, typically at approximately nine months post-surgery.' This clarification directly addresses the concern regarding assessment timing standardization and enhances reproducibility. Please see the revised Section 2.4.

Comment 2: The authors state that an a priori power analysis was conducted using a repeated-measures ANOVA in G*Power (yielding a target of 44 participants). Since the study utilizes a complete-case approach (no imputation) and retrospective data, please clarify if you initially extracted a larger number of records and filtered them down to the final 45 who had complete datasets, or if exactly 45 met the criteria. Stating the initial pool size versus the final included sample (attrition/exclusion rate) would strengthen the methodological transparency.

We fully agree. The initial screening pool and exclusion process are now explicitly reported in Section 2.1: 'A total of 575 patient records were initially reviewed. Of these, 412 had assessments at only two time points and were excluded, 118 had assessments at three time points and were excluded, and the first 45 consecutive records containing complete data across all four rehabilitation phases were included. Recruitment was stopped at 45 to remain consistent with the a priori sample size estimate of 44 participants.' A CONSORT-style flow diagram has also been added as Figure 1 to visually illustrate this process. Please see the revised Section 2.1 and Figure 1.

Comment 3: The finding that psychological readiness continues to improve even after kinesiophobia reductions stabilize is a highly valuable clinical insight. I suggest expanding briefly in the discussion on practical ways clinicians might use this temporal dissociation (e.g., implementing specific exposure therapies or mastery-based tasks during mid-to-late rehabilitation to bridge the gap between fear reduction and readiness).

We thank the reviewer for highlighting this as a particularly valuable finding. Section 4.5 (Clinical Implications) has been expanded accordingly. The revised text now reads: 'The observed temporal dissociation between kinesiophobia stabilization and continued readiness improvement suggests that psychological intervention should not cease once fear levels decline. Clinicians may consider implementing exposure-based therapies and mastery-oriented tasks during mid-to-late rehabilitation to bridge the gap between fear reduction and full psychological readiness for RTS. Structured progression through increasingly challenging sport-specific tasks may support confidence accumulation during this critical period.' Please see the revised Section 4.5.

Comment 4: Rehabilitation phases are defined entirely based on time (0-1 month, >1-3 months, etc.). However, modern ACL rehabilitation adopts a criteria-based approach where the patient progresses according to objective criteria (e.g., range of motion, strength symmetry, functional tests). Time-based staging ignores individual differences in recovery rates among patients. The authors need to better justify why this approach was chosen (perhaps due to the nature of retrospective data). Also, 'Phase Four' (>6 months) is a very broad range; there may be a difference between 6-9 months and 9+ months.

This is an excellent and important point. Section 2.1 has been revised to directly address it: 'Although time windows defined phase boundaries, progression was criteria-based; patients advanced only upon meeting objective thresholds including pain levels, range of motion, limb symmetry indices, strength, and functional performance, per the clinic's structured ACLR protocol.' Regarding Phase Four breadth: 'Variability within Phase Four reflects individual differences in criteria attainment. All Phase Four assessments were conducted at the formal RTS clearance visit, standardizing the evaluation point within this phase.' This clarifies that Phase Four was not assessed at varying points between 6-9 months, but specifically at the RTS clearance evaluation. The full criteria-based protocol is provided in Supplementary Material S1. Please see the revised Section 2.1.

Comment 5: On page 4, it states that evaluations are 'generally completed around RTS approval, approximately 9 months after surgery.' However, stage 4 is defined as >6 months. This means that stage 4 evaluations may have been performed at different times, ranging from 6 to 9 months, and this could affect the results. This discrepancy needs to be explained.

We thank the reviewer for identifying this apparent discrepancy. It has been addressed in two places. In Section 2.1, Phase Four is now defined as: 'Phase Four (>6 months, concluding at approximately 9 months at formal RTS clearance).' In Section 2.4, it is further clarified that: 'All Phase Four assessments were conducted at the formal RTS clearance evaluation, typically at approximately nine months post-surgery.' Therefore, the >6 month window represents the eligibility window, while the actual assessment point was standardized to the RTS clearance visit, which occurred at approximately 9 months. Please see the revised Sections 2.1 and 2.4.

Comment 6: In Table 1 on page 6, the spelling 'Bone-patellar tendon-bone' should be corrected. There are some sentences in the text where the word 'phases' is repeated unnecessarily (e.g., page 8, 'significant main effect of rehabilitation phases across the four rehabilitation phases'). Such expressions could be simplified.

Both corrections have been made. (1) The graft type is now written in full as 'Bone-patellar tendon-bone autograft' consistently throughout Table 1 and the manuscript. (2) The redundant phrase in Section 3.3 has been simplified to: 'Linear mixed model analysis demonstrated a statistically significant main effect of rehabilitation phase for all outcome measures.' Additional instances of unnecessary repetition of 'phases' have been reviewed and simplified throughout the manuscript. Please see the revised Table 1 and Section 3.3.