Age and Sex Differences in Anterior Cruciate Ligament–Return to Sport after Injury Subscale Scores of Emotion,Risk Appraisal,and Confidence After ACL Reconstruction

Abstract

Background:

The Anterior Cruciate Ligament–Return to Sport after Injury (ACL-RSI) scale is widely used after anterior cruciate ligament reconstruction (ACLR), but its 3 subscale domains of emotion, risk appraisal, and confidence are rarely considered when assessing readiness to return to sport (RTS). Current guidelines for ACL-RSI scores at time of RTS are derived from adult-only studies, and there is a need for age- and sex-specific data to guide RTS decision-making.

Purpose/Hypothesis:

The purpose of this study was to investigate differences in ACL-RSI subscale scores by age and sex. It was hypothesized that males and teens would report higher scores on emotion, confidence, and risk appraisal subscales compared with females and adults.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

ACL-RSI data were obtained from a multisite clinical outcome registry. Participants were included if they were between 6 and 12 months after primary, unilateral ACLR. Sex subgroups (female, male) and age subgroups (teen: 14-18 years; adult: 19-30 years) were established and compared to identify potential sex- and age-related differences in the ACL-RSI scale (total, subscales, and item scores). Descriptive statistics were computed and multiple 2-way analyses of variance were used to determine main effects and interactions between sex and age group. The significance level (α) was set to .05.

Results:

A total of 154 participants (mean age, 20.2 ± 3.8 years; 53.9% female; mean time after ACLR, 8.7 ± 2.1 months) were included. The mean ACL-RSI total score across the cohort was 67.92 ± 24.65. A significant main effect of age group on ACL-RSI total score was found as teens exhibited significantly greater psychological readiness compared with adults (mean difference, 10.91 points). A significant main effect of age group on the confidence subscale score was found, with teens reporting significantly higher confidence in returning to sport compared with adults (mean difference, 14.05 points). The main effect of sex on ACL-RSI total score was not significant (P = .337).

Conclusion:

Teens demonstrated significantly higher total scores and confidence on the ACL-RSI scale compared with adults. Therefore, when assessing a teen athlete's psychological preparedness to RTS, target scores determined from adult data may not be appropriate. Sex was not found to influence ACL-RSI scores. Future work should strive to create age- and sex-specific ACL-RSI cutoff scores for successful RTS after ACLR in teen athletes.

Keywords

anterior cruciate ligament psychological readiness rehabilitation

Anterior cruciate ligament reconstruction (ACLR) is a significant life event for youth athletes, with only 55% able to successfully return to competitive sport.⁴ Criteria used for return to sport (RTS) clearance after ACLR primarily focus on biological healing and functional recovery, with less attention paid to patient-reported function and mental preparedness.⁷ Consensus guidelines for RTS decision-making recommend utilizing a biopsychosocial model to emphasize the influence that psychological perceptions have on RTS success.²

Psychological readiness is a multidimensional construct because athletes can benefit from being confident, self-aware, and emotionally prepared before they RTS. Of those unsuccessful in RTS after ACLR, 65% report a psychological reason limiting them.²⁰ Fear of reinjury (77% of responses) and lack of confidence (15% of responses) are among the most commonly reported psychological limitations when unsuccessful to RTS.²⁰ Male and female patients report different psychological factors impacting their RTS clearance, including distress, self-efficacy, locus of control, and fear of reinjury.^18,25 As discrepancies in psychological responses (eg, confidence and fear) exist between patients, using a general scale of all dimensions of psychological readiness may not be specific enough to best assess and address the limitations of adolescent athletes.

The Anterior Cruciate Ligament–Return to Sport after Injury (ACL-RSI) scale provides a reliable and valid assessment of psychological readiness for sport after ACLR.^26,28 Psychological readiness has been shown to have a strong relationship with biological and functional outcomes after ACLR, including an increased ability to return to a previous level of sport.^3,5,10,13,31 Age and sex may be associated with psychological readiness after ACLR, with adolescents and males reporting increased readiness compared with older patients and females.^15,19,30 With adolescents¹¹ and female sex²² commonly associated with poorer outcomes after ACLR, there is a heightened need for age- and sex-specific data on psychological readiness to guide RTS decision-making.

The ACL-RSI scale contains 3 subscales: emotion, risk appraisal, and confidence.²⁸ Although the ACL-RSI total score continues to be widely used after ACLR, these subscales are rarely calculated or considered when assessing RTS readiness. In the adult population, the ACL-RSI subscale scores have been strongly related to each other, allowing the ACL-RSI total score to be utilized as a common standard of practice.^16,26,28 Recently, Webster and Feller²⁷ further investigated psychological readiness in the adolescent population and noted differences in these 3 subscale constructs (emotion subscale, confidence subscale, and risk appraisal subscale) that were not previously seen in the adult population. Understanding these unique constructs could help clinicians develop more appropriate interventions to enhance outcomes, rather than just using a global, unidimensional construct of psychological readiness. The authors discuss benefits of further exploration into ACL-RSI subscale scores to assess the most influential psychological factors in this population.²⁷

Clinicians may influence the psychological recovery of athletes, and a comprehensive understanding of specific psychological limitations can help guide treatment strategies aimed at preparedness for RTS.²⁹ The lack of published normalized data regarding ACL-RSI scores in the teen population limits clinicians’ ability to interpret these subscales after ACLR. There is a call for increased specificity in pediatric and adolescent anterior cruciate ligament (ACL) research, specifically utilizing multicenter registry studies to obtain optimal sample sizes.¹ Therefore, the purpose of this study was to investigate differences in ACL-RSI subscale scores by age and sex at the time of RTS testing. We hypothesized that males and younger patients (teens) would report higher scores on emotion, confidence, and risk appraisal subscales compared with females and older patients (adults).

Methods

This was a multisite study from the ACL Reconstruction Rehabilitation Outcomes Workgroup (ARROW) clinical outcome registry. The purpose of ARROW is to combine data and resources from a geographically diverse consortium of researchers at affiliated universities, hospitals, and research sites to improve clinical decision-making and patient care after ACLR. Data were collected as a part of separate institutional review board (IRB)–approved research studies (University of Virginia: HSR 220225) at each site, and then a limited data set from each site was aggregated in an IRB-approved registry housed and managed by study team members at the University of Virginia (HSR 230335).

Patients

Patients were included if they were within 6 to 12 months after primary, unilateral ACLR, and between the ages of 14 and 30 years. If data were captured at multiple time points within 6 to 12 months, the latest time point was included for analysis to best align with clearance to RTS. Sex (female, male) and age group (teen: 14-18 years; adult: 19-30 years) were recorded to subsequently identify potential sex- and age-related differences in the ACL-RSI scale (total, subscales, and item scores). The teenage group of 14 to 18 years represents the range of peak ACL injury incidence.⁶ Biological age was not assessed in this study; therefore, chronological age terminology was used to describe groups. The term “teen” was selected as a combination of the “early teen” and “late teen” subcategories.⁸

Patient-Reported Outcome Measures

The ACL-RSI scale is a 12-item scale used to measure psychological readiness to RTS after ACLR. It is valid in both teens and adults.^9,28 The ACL-RSI scale consists of 3 subscales that influence RTS: risk appraisal (2 items), confidence in performance (5 items), and negative emotional response (5 items) (Table 1). The ACL-RSI scale is scored from 0 to 100, with a higher score indicative of greater readiness to RTS. The total score is computed by averaging the 12 item scores, each captured on a 100-point scale. Similarly, subscale scores are computed by averaging the items corresponding to each subscale. The ACL-RSI scale demonstrates high validity and internal consistency (Cronbach α = 0.96).²⁶

Table 1

ACL-RSI Items by Subscale ^a

Question No.	ACL-RSI Item	Subscale
1	Are you confident that you can perform at your previous level of sport participation?	Confidence
2	Do you think you are likely to reinjure your knee by participating in your sport?	Risk appraisal
3	Are you nervous about playing your sport?	Emotion
4	Are you confident that your knee will not give way by playing your sport?	Confidence
5	Are you confident that you could play your sport without concern for your knee?	Confidence
6	Do you find it frustrating to have to consider your knee with respect to your sport?	Emotion
7	Are you fearful of reinjuring your knee by playing your sport?	Emotion
8	Are you confident about your knee holding up under pressure?	Confidence
9	Are you afraid of accidentally injuring your knee by playing your sport?	Emotion
10	Do thoughts of having to go through surgery and rehabilitation prevent you from playing your sport?	Risk appraisal
11	Are you confident about your ability to perform well at your sport?	Confidence
12	Do you feel relaxed about playing your sport?	Emotion

ACL-RSI, Anterior Cruciate Ligament–Return to Sport after Injury.

Statistical Analysis

Means and standard deviations were computed for all continuous variables, including age, months since surgery, and ACL-RSI subscale and total scores. Given the ordinal nature of the ACL-RSI item scores, medians and interquartile ranges were computed. Specifically, interquartile ranges were computed as the difference between the 25th and 75th percentiles. The main effects of sex (female, male) and age group (teen: 14-18 years; adult: 19-30 years), as well as the interaction between sex and age group, on ACL-RSI subscale and total scores were identified using multiple 2-way analyses of variance. Similarly, for ACL-RSI item scores, an ordinal logistic regression model was performed. The significance level (α) was set to .05. If a significant interaction effect was found, post hoc analysis was performed to compare the means of one factor at each level of the second factor using a Bonferroni adjustment (α = .013). All analyses were performed using IBM SPSS Statistics for Windows (Version 224.0; IBM Corp).

Results

A total of 154 patients (mean age, 20.2 ± 3.8 years; mean time from after, 8.7 ± 2.1 months) were included for analysis. The cohort consisted of 53.9% female patients, and 45.5% of patients were included in the teen subgroup. The teen subgroup had a mean age of 16.91 ± 1.14 years, while the adult subgroup had a mean age of 22.85 ± 3.07 years. Subgroup breakdowns are presented in Table 2. Overall, the mean ACL-RSI total score across the cohort was 67.92 ± 24.65, and the mean emotion, confidence, and risk appraisal subscale scores were 63.05 ± 28.07, 72.74 ± 26.04, and 67.44 ± 28.40, respectively.

Table 2

ACL-RSI Item, Subscale, and Total Scores by Age Group and Sex ^a

	Male		Female
	Teen (n = 26)	Adult (n = 45)	Teen (n = 44)	Adult (n = 39)
Items
Q1 (Confidence)	90.00 [20.00]	80.00 [30.00]	80.00 [37.50]	70.00 [30.00]
Q2 (Risk appraisal)	90.00 [50.00]	70.00 [52.50]	80.00 [40.00]	70.00 [40.00]
Q3 (Emotions)	70.00 [60.00]	70.00 [60.00]	90.00 [37.50]	70.00 [50.00]
Q4 (Confidence)	90.00 [20.00]	70.00 [42.50]	90.00 [40.00]	70.00 [50.00]
Q5 (Confidence)	90.00 [20.00]	70.00 [52.50]	80.00 [50.00]	70.00 [60.00]
Q6 (Emotions)	55.00 [55.00]	55.00 [70.00]	80.00 [67.50]	60.00 [60.00]
Q7 (Emotions)	70.00 [50.00]	60.00 [60.00]	80.00 [57.50]	60.00 [40.00]
Q8 (Confidence)	90.00 [30.00]	80.00 [32.50]	90.00 [40.00]	70.00 [40.00]
Q9 (Emotions)	70.00 [60.00]	70.00 [70.00]	80.00 [65.00]	60.00 [40.00]
Q10 (Risk appraisal)	80.00 [60.00]	75.00 [70.00]	90.00 [37.50]	60.00 [50.00]
Q11 (Confidence)	90.00 [20.00]	80.00 [42.50]	90.00 [37.50]	80.00 [40.00]
Q12 (Emotions)	80.00 [50.00]	70.00 [50.00]	80.00 [40.00]	70.00 [50.00]
Subscales
Emotions	67.54 ± 26.20	61.29 ± 27.32	67.14 ± 28.48	55.68 ± 30.37
Confidence	85.19 ± 19.06	69.09 ± 25.12	76.36 ± 25.39	63.03 ± 28.93
Risk appraisal	69.07 ± 30.67	64.57 ± 28.52	73.75 ± 25.99	61.18 ± 28.63
ACL-RSI total score	75.96 ± 20.31	65.04 ± 22.54	72.08 ± 25.00	62.81 ± 25.98

Item scores are presented as median [IQR], and subscale scores are presented as mean ± SD for each age group within each sex. Significant age group differences are noted in bold. No significant sex differences were found, and no interaction effects between sex and age group were identified. Thus, neither is noted in the table. ACL-RSI, Anterior Cruciate Ligament–Return to Sport after Injury; Q, question.

A significant main effect of age group on ACL-RSI total score was identified (F[1, 150] = 7.406; P = .007; η_p² = 0.047) (Figure 1). Specifically, teens exhibited significantly greater psychological readiness compared with adults (mean difference, 10.91 points). However, the main effect of sex was not significant (P = .337), and no significant interaction effect between sex and age group on ACL-RSI total score was found (P = .996). Similarly, a significant main effect of age group on the confidence subscale score was observed (F[1, 152] = 11.552; P < .001; η_p² = 0.071), with teens reporting significantly higher confidence in returning to sport compared with adults (mean difference, 14.05 points). The main effect of sex (P = .103) and the interaction effect (P = .621) on the confidence subscale score were not significant. Additionally, no differences by sex, age group, or the interaction between sex and age group were found for the emotion or risk appraisal subscales.

Figure 1.

Anterior Cruciate Ligament–Return to Sport after Injury (ACL-RSI) subscale, total, and item scores by age group. Significant age group differences are noted with an asterisk.

Contributing to the age-specific difference in confidence subscale score, teens reported greater confidence in their knee not giving way by playing their sport (X²[1, 156] = 5.708; P = .017), their knee holding up under pressure (X²[1, 156] = 6.283; P = .012), and their ability to perform well at their sport (X²[1, 156] = 3.990; P = .046). No significant differences by sex or the interaction between sex and age group were found for the any of the confidence subscale items. Lastly, a significant main effect of age group on 1 item in the emotion subscale score was found. Specifically, teens reported feeling more relaxed about playing their sport (X²[1, 156] = 6.609; P = .010). The main effect of sex (P = .119) and the interaction effect between sex and age group (P = .385) were not significant. Furthermore, no significant differences by sex, age group, or the interaction between sex and age group were found for the remaining emotion subscale items or the 2 risk appraisal subscale items.

Discussion

The purpose of this study was to investigate differences in ACL-RSI subscale scores by age and sex. Both male and female teens reported significantly greater confidence in performance compared with adults. Male teens reported the highest total ACL-RSI scores of all groups, but the main effect of sex was not statistically significant for ACL-RSI total or subscale scores. Overall, these results indicate a stark difference in psychological readiness between teens and adults after ACLR that should be considered at the time of RTS.

Our results are comparable to previous studies reporting ACL-RSI total scores in teens 6 to 12 months postoperatively,^15,19 supporting the notion that younger age positively affects ACL-RSI scores.³⁰ Milewski et al¹⁹ reported significantly higher ACL-RSI mean total scores in adolescents (61.5 ± 20.4) versus adults (52.5 ± 19.8), although their total scores trended 15% to 20% lower than those in our study. This is likely because of their earlier time point of collection (6 months postoperatively) versus our mean time point of 8.7 ± 2.1 months postoperatively, as ACL-RSI scores improve throughout the first year of postoperative ACLR rehabilitation.²⁴ As current practice patterns have shifted away from clearing teen athletes for RTS before 9 months postoperatively, having ACL-RSI total scores and subscale scores near the time of RTS decision-making may be most beneficial for clinicians.¹⁴

There are many factors that can influence reported psychological readiness for sport in teens versus adults. Current target scores for the ACL-RSI scale are from adult-based studies, with a total score >56 at 4 months postoperatively⁵ and a total score >72 at 12 months postoperatively¹⁷ predictive of successful RTS. Social factors may influence an adult's perspective of their psychological readiness for RTS after ACLR. Fones et al¹³ identified that those athletes transitioning to adulthood who did not RTS reported life changes, such as changes in training or starting work/college, as one of the primary barriers for RTS. Teens have access to organized competitive and recreational sports through school leagues, and commitment to sport may look very different in adults when compared with teens.¹³ We postulate that our findings on the ACL-RSI scale may also be due to adults viewing RTS more negatively because of decreased access to competitive sport, as well as the financial and time burdens of ACLR and subsequent rehabilitation. Filbay et al¹² identified that adults after ACLR modify their activity preferences and alter their lifestyles to accommodate for knee impairments and improve quality of life. With these differences in mind, clinicians may need to hold higher expectations for ACL-RSI total scores in teens and consider subscale scores, instead of relying on previously utilized target scores derived from adult populations.

Our data show both male and female teens reporting significantly higher scores on confidence items in comparison with adults. Although high confidence is a key component in returning to competitive sport, it is not protective from reinjury.²³ Paterno et al²³ included females with high self-reported confidence as a predictive variable in an algorithm that attempts to identify young athletes at high risk for secondary ACL injury. Using the confidence subscale score in addition to other physical performance metrics (eg, knee strength and functional performance) may be useful to assess patients’ readiness to progress in rehabilitation. Disproportionate physical and mental recovery may lead to poor outcomes, and, as a degree of caution, low confidence could be beneficial if the patient is physically not ready to advance in activity. Clinicians should be aware of the increased confidence scores common in teens, as greater confidence could inflate ACL-RSI total scores and overshadow suboptimal emotion responses if only the total ACL-RSI score is being evaluated.

We hypothesized that males would have higher scores on the ACL-RSI scale compared with females. In our sample, the mean total score for teen males (75.96 ± 20.31) trended higher than the mean total score for teen females (72.08 ± 25.00), and the mean total score for adult males (65.04 ± 22.54) trended higher than the mean total score for adult females (62.81 ± 25.98), but no significant main effect of sex for the ACL-RSI total score or subscale scores was found. Previous studies reporting sex-specific ACL-RSI scores have shown higher scores in males versus females,^15,19 although a recent meta-analysis of 2618 patients²¹ after ACLR indicated only a mean difference of approximately 5 points on the ACL-RSI scale between sexes.

This paper provides the first available data on ACL-RSI individual item responses by teens after ACLR. By isolating the individual questions, or items, of the ACL-RSI scale and reporting mean subscale scores, our results can help clinicians more accurately assess how different components of their patients’ psychological readiness compare with age- and sex-specific data. Using the individual item scores is important to make patient-specific recommendations and deliver effective interventions before RTS. In our study, the emotion subscale scored the lowest across both sex and age groups. Fear of reinjury and stress have been reported as major impediments in returning to sport.¹³ Being able to identify abnormally low scores on specific emotion items can guide the health care team toward targeted cognitive interventions to increase the likelihood of successful RTS.

Limitations

There were a few limitations in this study. Because of the variances between sites, ACL-RSI data were collected at different time points between 6 and 12 months postoperatively (8.7 ± 2.1 months), and it was not guaranteed that patients successfully returned to sport at this assessment time point. Additionally, there were insufficient data from the youngest age group (12-14 years), requiring those patients to be excluded. Early teens may present differently than late teens with regard to psychological readiness and should be considered a priority in future large, multicenter studies. The level of competition and type of sport for patients included in this study were not recorded. Knowing that the ACL-RSI scale was developed specifically for athletes planning to RTS after ACLR,²⁸ the sport-specific items included in the ACL-RSI scale may not be applicable for those who participate in general, unorganized recreational forms of sport as opposed to competitive, organized sport. Adults may have less access to organized competitive sport¹³ and therefore a lower level of activity compared with the teen group.

Conclusion

Teens demonstrate significantly higher total scores on the ACL-RSI scale in comparison with adults. When assessing a teen athlete's psychological preparedness to RTS, target scores determined from adult data may not be appropriate. Both male and female teens show increased confidence subscale scores when compared with adults, which may inflate ACL-RSI total scores, and disguise limited emotional readiness. Clinicians should utilize ACL-RSI subscale or individual item scores to make patient-specific recommendations and provide appropriate interventions. Future work should strive to create age- and sex-specific ACL-RSI cutoff scores for successful RTS after ACLR in teen athletes.

Authors

Dylan P. Roman, DPT (Connecticut Children's, Hartford, Connecticut, USA); Sophia Ulman, PhD (Scottish Rite for Children, Dallas, Texas, USA); Lauren Butler, DPT (Florida International University and Nicklaus Children's Hospital, Miami, Florida, USA); Cody Walker, DAT, ATC, CSCS (Arkansas Children's Hospital, Little Rock, Arkansas, USA); Taylor Douthit, DPT (Children’s Health Andrews Institute, Gulf Breeze, Florida, USA); Christopher M. Kuenze, PhD, ATC (University of Virginia, Charlottesville, Virginia, USA); Victor V. Prati, DPT, Brant Sachleben, MD (Arkansas Children's Hospital, Little Rock, Arkansas, USA); Lucy Phan, MS, CSCS, Stephen LaPlante, MS, PT, ATC, Lee Pace, MD, Dhalston Cage, PT, DPT, MS, John Roaten, MD, John Abt, PhD, Dustin Loveland, MD, MBA (Children’s Health Andrews Institute, Gulf Breeze, Florida, USA); Elliot Greenberg, DPT, PhD, Meredith Link, PT, DPT, ATC, CSCS, Theodore Ganley, MD (Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA); Adam Weaver, PT, DPT, Nicholas Giampetruzzi, PT, MS, (Connecticut Children's, Hartford, Connecticut, USA); Brooke Farmer, MS, ATC, Terry L. Grindstaff, PhD, PT, ATC (Creighton University, Omaha, Nebraska, USA); Edward Chang, MD, Rachel Cherelstein, BS (Inova Health System, Falls Church, Virginia, USA); Corey D. Grozier, MS, Matthew Harkey, PhD, ATC, Arjun Parmar, BA, Jessica Tolzman, MS (Michigan State University, East Lansing, Michigan, USA); Alexa Martinez, DPT (Nicklaus Children's Hospital, Miami, Florida, USA); Jacob Landers, DPT (Scottish Rite for Children, Dallas, Texas, USA); Kylee Rucinski, PhD, MHA, Chelsea Harrison, PTA, Steven DeFroda, MD, Richard Ma, MD (University of Missouri, Columbia, Missouri, USA); Natalie Kupperman, PhD, ATC, Xavier Thompson, MS, ATC, Michelle Walaszek, PT, DPT, MS, Kevin Cross, PhD, ATC, PT (University of Virginia, Charlottesville, Virginia, USA); Elaine Reiche, ATC, CSCS, Caitlin Brinkman, MS, LAT, ATC, Tom Birchmeier, PhD, ATC, CSCS, Joseph M. Hart, PhD, ATC, Shelby Baez, PhD, ATC (University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA).

Footnotes

Final revision submitted February 21, 2024; accepted March 28, 2025.

One or more of the authors has declared the following potential conflict of interest or source of funding: E.C. is a consultant for Avanos Medical and has received research support from Arthrex. L.P. is a consultant for Arthrex and JRF Ortho and a paid speaker for Arthrex; has received research support from Arthrex; is a committee member of the American Orthopaedic Society for Sports Medicine and PRiSM; and owns stock in OutcomeMD. R.M. is a consultant for Johnson & Johnson; has received research support from Novocart, Moximed, and Cartiheal; is a committee member of the American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and American College of Sports Medicine; and serves on the Associate Editor Panel for Journal of Bone and Joint Surgery American and as a board member of the Rugby Research & Injury Prevention Group. T.G. has received research support from AlloSource and Vericel, educational support from Arthrex and Paladin Technology Solutions, and hospitality payments from Arthrex; is an associate editor of The American Journal of Sports Medicine; serves as a committee member of POSNA and PRiSM; serves as a board or committee member of IPOS and AAOS; and serves as a board member of the AAP Section on Orthopedics. S.D. has been a speaker for AO North America; is a consultant for Stryker; and has received research support from Stryker, Arthrex, OREF, and AANA. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Ethical approval for this study was obtained the University of Virginia (HSR 230335).

References

Ardern

Ekas

Grindem

, et al. 2018 International Olympic Committee consensus statement on prevention, diagnosis and management of paediatric anterior cruciate ligament (ACL) injuries. Br J Sports Med. 2018;52(7):422-438.

Ardern

Glasgow

Schneiders

, et al. 2016 Consensus statement on return to sport from the First World Congress in Sports Physical Therapy, Bern. Br J Sports Med. 2016;50(14):853-864.

Ardern

Osterberg

Tagesson

, et al. The impact of psychological readiness to return to sport and recreational activities after anterior cruciate ligament reconstruction. Br J Sports Med. 2014;48(22):1613-1619.

Ardern

Taylor

Feller

Webster

KE.

Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factors. Br J Sports Med. 2014;48(21):1543-1552.

Ardern

Taylor

Feller

Whitehead

Webster

KE.

Psychological responses matter in returning to preinjury level of sport after anterior cruciate ligament reconstruction surgery. Am J Sports Med. 2013;41(7):1549-1558.

Beck

Lawrence

JTR

Nordin

DeFor

Tompkins

ACL tears in school-aged children and adolescents over 20 years. Pediatrics. 2017;139(3):e20161877.

Burgi

Peters

Ardern

, et al. Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review. Br J Sports Med. 2019;53(18):1154-1161.

Butler

DiSanti

Sugimoto

, et al. Apples to oranges: inconsistencies in defining and classifying youth sport populations. Clin J Sport Med. 2023;33(1):1-4.

Cirrincione

Gross

Matsuzaki

, et al. Validation of the ACL-RSI scale in pediatric and adolescent patients. Am J Sports Med. 2023;51(12):3106-3111.

10.

Czuppon

Racette

Klein

Harris-Hayes

Variables associated with return to sport following anterior cruciate ligament reconstruction: a systematic review. Br J Sports Med. 2014;48(5):356-364.

11.

Dekker

Godin

Dale

, et al. Return to sport after pediatric anterior cruciate ligament reconstruction and its effect on subsequent anterior cruciate ligament injury. J Bone Joint Surg Am. 2017;99(11):897-904.

12.

Filbay

Crossley

Ackerman

IN.

Activity preferences, lifestyle modifications and re-injury fears influence longer-term quality of life in people with knee symptoms following anterior cruciate ligament reconstruction: a qualitative study. J Physiother. 2016;62(2):103-110.

13.

Fones

Kostyun

Cohen

Pace

JL.

Patient-reported outcomes, return-to-sport status, and reinjury rates after anterior cruciate ligament reconstruction in adolescent athletes: minimum 2-year follow-up. Orthop J Sports Med. 2020;8(11):2325967120964471.

14.

Grindem

Snyder-Mackler

Moksnes

Engebretsen

Risberg

MA.

Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808.

15.

Kostyun

Burland

Kostyun

Milewski

Nissen

CW.

Male and female adolescent athletes’ readiness to return to sport after anterior cruciate ligament injury and reconstruction. Clin J Sport Med. 2021;31(4):383-387.

16.

Kvist

Osterberg

Gauffin

, et al. Translation and measurement properties of the Swedish version of ACL-Return to Sports after Injury questionnaire. Scand J Med Sci Sports. 2013;23(5):568-575.

17.

Langford

Webster

Feller

JA.

A prospective longitudinal study to assess psychological changes following anterior cruciate ligament reconstruction surgery. Br J Sports Med. 2009;43(5):377-381.

18.

Lisee

DiSanti

Chan

, et al. Gender differences in psychological responses to recovery after anterior cruciate ligament reconstruction before return to sport. J Athl Train. 2020;55(10):1098-1105.

19.

Milewski

Traver

Coene

, et al. Effect of age and sex on psychological readiness and patient-reported outcomes 6 months after primary ACL reconstruction. Orthop J Sports Med. 2023;11(6):23259671231166012.

20.

Nwachukwu

Adjei

Rauck

, et al. How much do psychological factors affect lack of return to play after anterior cruciate ligament reconstruction? A systematic review. Orthop J Sports Med. 2019;7(5):2325967119845313.

21.

Obradovic

Manojlovic

Rajcic

et al. Males have higher psychological readiness to return to sports than females after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. BMJ Open Sport Exerc Med. 2024;10(4):e001996.

22.

Parsons

Coen

Bekker

Anterior cruciate ligament injury: towards a gendered environmental approach. Br J Sports Med. 2021;55(17):984-990.

23.

Paterno

Huang

Thomas

Hewett

Schmitt

LC.

Clinical factors that predict a second ACL injury after ACL reconstruction and return to sport: preliminary development of a clinical decision algorithm. Orthop J Sports Med. 2017;5(12):2325967117745279.

24.

Sadeqi

Klouche

Bohu

, et al. Progression of the psychological ACL-RSI score and return to sport after anterior cruciate ligament reconstruction: a prospective 2-year follow-up study from the French Prospective Anterior Cruciate Ligament Reconstruction Cohort Study (FAST). Orthop J Sports Med. 2018;6(12):2325967118812819.

25.

Sims

Mulcahey

MK.

Sex-specific differences in psychological response to injury and return to sport following ACL reconstruction. JBJS Rev. 2018;6(7):e9.

26.

Webster

Feller

JA.

Development and validation of a short version of the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) scale. Orthop J Sports Med. 2018;6(4):2325967118763763.

27.

Webster

Feller

JA.

Psychological readiness to return to sport after anterior cruciate ligament reconstruction in the adolescent athlete. J Athl Train. 2022;57(9-10):955-960.

28.

Webster

Feller

Lambros

Development and preliminary validation of a scale to measure the psychological impact of returning to sport following anterior cruciate ligament reconstruction surgery. Phys Ther Sport. 2008;9(1):9-15.

29.

Webster

Feller

Leigh

Richmond

AK.

Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction. Am J Sports Med. 2014;42(3):641-647.

30.

Webster

Nagelli

Hewett

Feller

JA.

Factors associated with psychological readiness to return to sport after anterior cruciate ligament reconstruction surgery. Am J Sports Med. 2018;46(7):1545-1550.

31.

Welling

Benjaminse

Lemmink

Gokeler

Passing return to sports tests after ACL reconstruction is associated with greater likelihood for return to sport but fail to identify second injury risk. Knee. 2020;27(3):949-957.