Association of Self-Reported Anxiety and Depression Symptoms with Knee Pain Severity in Individuals with Anterior Cruciate Ligament Reconstruction

Abstract

Background:

Psychological responses to injury are common after anterior cruciate ligament (ACL) injury and reconstruction (ACLR) and have been linked to knee-related pain during early recovery. However, it remains unknown whether anxiety and depression symptoms are associated with knee pain severity at later stages of recovery, when unresolved or recurrent psychological distress may persist.

Purpose/Hypothesis:

The purpose of this study was to examine the association of anxiety and depression symptoms with knee pain severity in individuals 3 to 12 months after ACLR. It was hypothesized that individuals who exhibited more severe anxiety and depression symptoms would report more knee pain.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

In total, 131 individuals who were 3 to 12 months after primary, unilateral ACLR (time since ACLR = 5.7 ± 1.7 months; age = 18.3 ± 2.1 years; 37.4% male) were included. Anxiety and depression symptoms were measured with the Patient-Reported Outcomes Measurement Information System Anxiety and Depression 4-item short forms, respectively, where higher scores reflect more severe symptoms. Knee pain was measured with the Knee injury and Osteoarthritis Outcome Score Pain subscale, where higher scores indicate less or no knee pain. Separate multiple hierarchical regression analyses were conducted to examine the association of self-reported anxiety and depression symptoms with knee pain severity. Sex, age, and time since ACLR were entered in step 1 of each model. Anxiety and depression symptom scores were entered in step 2 of their respective models, and the change in R² was examined.

Results:

Sex, age, and time since ACLR explained 3% of the variance in knee pain severity (R² = 0.031, P = .23). Anxiety symptoms accounted for an additional 25.7% of the variance in knee pain severity (ΔR² = 0.257, P < .001), while depression symptoms accounted for an additional 15.7% of the variance in knee pain severity (ΔR² = 0.157, P < .001).

Conclusion:

Self-reported anxiety and depression symptoms were significantly associated with knee pain severity in individuals 3 to 12 months after ACLR. These findings support assessment of anxiety, depression, and knee pain, even in the later phases of ACLR rehabilitation, to help inform clinical decision-making.

Keywords

anterior cruciate ligament pain psychology

Injury to the anterior cruciate ligament (ACL) is a prevalent sports-related injury that often necessitates ACL reconstruction (ACLR).²⁷ Although ACLR is considered the gold-standard treatment,²³ ACLR is regarded as a painful sports medicine procedure with pain-related complications commonly reported by patients after surgery.^29,39 After ACLR, approximately 53% of individuals do not return to their preinjury level of sport participation,² and 68% experience persistent knee symptoms.¹⁵ Unfortunately, increased knee pain is associated with decreased physical and psychological readiness for sport participation and is frequently cited as a barrier to successful return to sport by patients.^3,15 Given that failure to return to sport after ACLR is linked to worse quality of life outcomes,¹⁴ investigating factors that may contribute to knee pain after ACLR is essential for improving long-term outcomes in this population.

Advances in pain science have led to recognizing pain as a multidimensional experience influenced by biological, psychological, and social factors.²¹ Growing evidence indicates that negative psychological factors commonly experienced after musculoskeletal injury, such as anxiety and depression, may influence pertinent aspects of injury recovery, including pain perception.²⁰ Importantly, this relationship is often bidirectional, in which the presence of pain may also contribute to the exacerbation of negative moods and emotions.⁵ This established link between psychological distress and pain after musculoskeletal injury may be particularly relevant for individuals with ACLR, who often demonstrate changes in emotional functioning throughout rehabilitation.

Individuals who experience an ACL injury and subsequent reconstruction frequently exhibit an increase in negative emotions such as anxiety, characterized by increased worry and apprehension, and depression, marked by persistent feelings of sadness and hopelessness.^1,17,34 Previous research has shown that anxiety and depression symptoms commonly peak during the first 6 weeks after ACLR, a period during which these symptoms are also associated with increased pain perception.⁴ While some individuals may experience a decline in anxiety and depression symptoms throughout this early postsurgical period,⁴ others may continue to encounter changes in emotional functioning throughout various stages of recovery, including an increase in depression during the middle phase of rehabilitation,³¹ as well as heightened anxiety during the later return-to-sport phase.⁷ It is thus possible that anxiety and depression symptoms may continue to contribute to an individual's pain experience throughout the ACLR rehabilitation process.

Despite evidence linking psychological distress and pain in the early postoperative period, it remains unknown whether anxiety and depression symptoms are associated with knee pain severity at later stages of recovery after ACLR, when individuals may continue to experience unresolved or new episodes of psychological distress. Therefore, the purpose of this study was to examine the association of anxiety and depression symptoms with knee pain severity in individuals 3 to 12 months after ACLR. We hypothesized that individuals who exhibited more severe anxiety and depression symptoms would report more knee pain. Characterizing an association between anxiety and depression symptoms with knee pain may help to identify a need for integrating psychologically informed treatment approaches into musculoskeletal rehabilitation programs to help address psychological factors that can contribute to knee pain after ACLR.

Methods

Study Design

A cross-sectional analysis of a larger, ongoing prospective study examining clinical outcomes after ACLR was conducted. The study was approved by the Michigan State University Institutional Review Board, and informed consent (>18 years old) or parental informed consent and child assent (<18 years old) was obtained before participant study enrollment. Eligible participants were between the ages of 14 and 25 and had undergone primary, unilateral ACLR 3 to 12 months before data collection. Individuals were excluded if they had a history of secondary ACL injury or if they underwent a multiligament reconstruction at the same time as their ACLR (Figure 1). Participants were consecutively enrolled and took part in a single data collection session in a controlled laboratory setting between 2021 and 2023 that included completion of a demographics questionnaire and basic anthropometric measurements (eg, height, weight). Participants were also asked to self-report their date of surgery, graft type, and whether any meniscal procedures were performed at the time of ACLR. If participants were unable to recall this information or it could not be determined from personal records, the data were considered missing for the current study. Participants then completed self-administered questionnaires related to anxiety, depression, and knee pain.

Figure 1.

Flow diagram of individuals who underwent anterior cruciate ligament reconstruction, were enrolled in the ongoing prospective study, and then were included or excluded from the current analysis.

Instrumentation

The Patient-Reported Outcomes Measurement Information System (PROMIS) Anxiety 4a–Adult v1.0 was used to measure symptoms of anxiety. The PROMIS Anxiety 4a includes 4 items that assess emotional distress caused by hyperarousal, fear, anxious misery, and somatic symptoms related to arousal over the past 7 days.³³ The PROMIS Depression 4a–Adult v1.0 was used to measure symptoms of depression. The PROMIS Depression 4a includes 4 items that assess negative affect, mood, self-image, and social interaction over the past 7 days.³³ Items on each questionnaire are scored on a Likert scale from 1 (never) to 5 (always). Item scores are summed to calculate a raw score from 4 to 20 and are then converted to a standardized T score based on the US general population. PROMIS Anxiety 4a T scores range from 40.3 to 81.6, where higher scores indicate more severe anxiety symptoms. PROMIS Depression 4a T scores range from 41.0 to 70.4, where higher scores indicate more severe depression symptoms. The PROMIS Anxiety and Depression questionnaires were selected as brief, validated screening tools commonly used in clinical and rehabilitation settings to measure general psychological symptom burden and are reliable when measuring psychological distress in the orthopaedic knee population.^24,33

The adult version of the Knee injury and Osteoarthritis Outcome Score (KOOS) Pain subscale was used to measure knee pain severity.³⁷ The KOOS Pain subscale includes 9 items that assess how often individuals experience knee pain, as well as the amount of knee pain individuals have experienced in the past 7 days during knee-related activities, such as twisting, straightening, bending, walking, going up/down stairs, sleeping, sitting/lying, and standing. Each item is scored on a 5-point Likert scale from 0 to 4 before being normalized and represented on a 0 to 100 scale, where higher scores indicate less or no knee pain. The KOOS Pain subscale demonstrates excellent internal consistency (Cronbach’s α = 0.91) and reliability (intraclass correlation coefficient = 0.93) in individuals with ACLR.²²

Statistical Analyses

Patient-reported outcome data were assessed for normality using the Shapiro-Wilk test. Descriptive statistics (mean [SD]) were calculated for demographic data, and median and interquartile range values were calculated for anxiety, depression, and knee pain scores due to nonnormal data distribution. Separate multiple hierarchical regression analyses were used to determine the association between self-reported anxiety and depression symptoms with knee pain severity. The order of input of the variables for each model was determined a priori, with sex, age, and time since ACLR being entered in the first step of each analysis due to their potential influence on knee pain severity.^4,10,28 Anxiety and depression symptom scores were entered in the second step of their respective models, and the change in R² was examined. When performing linear regression analyses, a minimum of 10 participants should be included per predictor variable.⁹ Thus, although an a priori power analysis was not conducted, with only 4 predictor variables included in each model, our sample size exceeded the 10-participant per predictor variable recommendation, indicating that our analyses were adequately powered. Model residuals were examined to verify the assumptions of linearity, independence of errors, homoscedasticity, the absence of significant outliers, and normality; no violations were detected. A priori α was set at P < .05. Cohen's f² effect sizes were also calculated to quantify the proportion of variance explained by the models relative to the unexplained variance and to determine the clinical meaningfulness of the associations. Effect sizes were interpreted as small (≥0.02), moderate (≥0.15), or large (≥0.35).⁸

A post hoc correlation analysis was also conducted to explore whether the relationship between anxiety and depression symptoms with knee pain severity varied across subgroups of our cohort based on relevant phases of recovery after ACLR. Participants were stratified into early (<6 months after ACLR; n = 79) and late (≥6 months after ACLR; n = 52) recovery groups, and Spearman's ρ correlation coefficients were calculated between scores on the KOOS Pain subscale and each PROMIS scale within these subgroups. Correlation coefficients were interpreted as follows: 0.00 to 0.19, very weak; 0.20 to 0.39, weak; 0.40 to 0.59, moderate; 0.60 to 0.79, strong; and 0.80 to 1.0, very strong.¹² Correlations were considered statistically significant if α levels were <.05. All analyses were completed using Stata (StataCorp LLC) statistical software.

Results

A total of 131 participants with a history of primary, unilateral ACLR were included (age = 18.3 ± 2.1 years; time since ACLR = 5.7 ± 1.7 months; 49 men [37.4%]). Participants reported a median score of 48 (IQR = 15.5) on the PROMIS Anxiety, 41 (IQR = 10.8) on the PROMIS Depression, and 91.7 (IQR = 11.11) on the KOOS Pain subscale. Participant characteristics are presented in Table 1.

Table 1

Participant Characteristics ^a

Characteristic	Value
Sex
Female	82 (62.5)
Male	49 (37.4)
Age, y	18.30 ± 2.05
Height, cm	170.77 ± 8.42
Weight, kg	68.33 ± 13.07
Time since ACLR, mo	5.67 ± 1.71
ACLR graft type
Patellar tendon autograft	32 (24.4)
Semitendinosus/gracilis autograft	72 (55.0)
Quadriceps tendon autograft	17 (13.0)
Allograft	1 (0.007)
Missing	9 (6.9)
History of concomitant meniscal repair or meniscectomy with ACLR
Yes	36 (27.5)
No	84 (64.1)
Missing	11 (8.4)
PROMIS Anxiety	48 [15.5]
PROMIS Depression	41 [10.8]
KOOS Pain	91.67 [11.11]

Data are reported as frequency (%), mean ± standard deviation, or median [interquartile range]. ACLR, anterior cruciate ligament reconstruction; KOOS, Knee injury and Osteoarthritis Outcome Score; PROMIS, Patient-Reported Outcomes Measurement Information System.

Results of the hierarchical regression analyses indicated that sex, age, and time since ACLR explained 3% of the variance in KOOS Pain scores (F_{3, 127} = 1.36, R² = 0.031, P = .26). PROMIS Anxiety scores accounted for an additional 25.7% of the variance in KOOS Pain scores (F_{4, 126} = 12.74, ΔR² = 0.257, P < .001; Table 2). Specifically, every 1-point increase in PROMIS Anxiety T score was associated with a 0.49-point decrease in KOOS Pain score. The significant association between PROMIS Anxiety scores and KOOS Pain scores resulted in a large effect size (f² = 0.40).

Table 2

Hierarchical Regression Analysis of Sex, Age, Time Since ACLR, and PROMIS Anxiety Scores on KOOS Pain Scores ^a

Step	Variable	F	R ²	ΔR²	β	P Value	95% CI
Step 1	Sex				2.139	.152	–0.798 to 5.076
	Age				–0.377	.285	–1.071 to 0.318
	Time since ACLR	1.36	0.031		0.405	.337	–0.426 to 1.237
Step 2	Sex				0.136	.918	–2.460 to 2.731
	Age				–0.154	.614	–0.755 to 0.448
	Time since ACLR				0.239	.512	–0.629 to −0.344
	PROMIS Anxiety	12.74	0.288	0.257	–0.487	<.001^b	–0.629 to −0.344

Mean variance inflation factor for all predictors = 1.04, indicating no evidence of multicollinearity. ACLR, anterior cruciate ligament reconstruction; PROMIS, Patient-Reported Outcomes Measurement Information System.

Statistical significance P < .05.

After adjusting for the influence of sex, age, and time since ACLR, PROMIS Depression scores accounted for an additional 15.7% of the variance in KOOS Pain scores (F_{4, 126} = 7.29, ΔR² = 0.157, P < .001; Table 3). Every 1-point increase in PROMIS Depression T score was associated with a 0.43-point decrease in KOOS Pain score. The significant association between PROMIS Depression scores and KOOS Pain scores was accompanied by a medium effect size (f² = 0.23).

Table 3

Hierarchical Regression Analysis of Sex, Age, Time Since ACLR, and PROMIS Depression Scores on KOOS Pain Scores ^a

Step	Variable	F	R ²	ΔR²	β	P Value	95% CI
Step 1	Sex				2.139	.152	–0.798 to 5.076
	Age				–0.377	.285	–1.071 to 0.318
	Time since ACLR	1.36	0.031		0.405	.337	–0.426 to 1.237
Step 2	Sex				0.136	.469	–1.733 to 3.743
	Age				–0.154	.876	–0.703 to 0.599
	Time since ACLR				0.239	.464	–0.482 to 1.050
	PROMIS Depression	7.29	0.188	0.157	–0.430	<.001^b	–0.602 to −0.257

Statistical significance P < .05.

Our post hoc correlation analyses revealed that among the early recovery group (<6 months after ACLR), KOOS Pain scores were moderately inversely related to PROMIS Anxiety scores (r = −0.45, P < .001) and weakly inversely related to PROMIS Depression scores (r = −0.31, P = .005). In the late recovery group (≥6 months after ACLR), KOOS Pain scores were strongly inversely related to PROMIS Anxiety scores (r = −0.65, P < .001) and moderately inversely related to PROMIS Depression scores (r = −0.43, P = .001).

Discussion

The purpose of this study was to investigate the association between self-reported anxiety and depression symptoms with knee pain severity in individuals 3 to 12 months after ACLR. Our findings supported our hypothesis, as individuals with ACLR who exhibited more severe anxiety or depression symptoms reported more knee pain. Interestingly, participants had a median PROMIS Depression score of 41 and a median PROMIS Anxiety score of 48, which are both considered subclinical and below the general US population average PROMIS score of 50,^6,40 indicating that this cohort generally reported relatively low levels of anxiety and depression. However, the results of our hierarchical regression analyses propose that even these modest symptom levels may meaningfully influence pain perception throughout rehabilitation and return-to-sport phases after ACLR. The medium and large effects observed further indicate moderate and strong clinically meaningful associations between symptoms of depression and anxiety with knee pain, respectively.

Although previous research has demonstrated a link between anxiety, depression, and pain up to 6 weeks after ACLR,⁴ our study is among the first to identify an association between anxiety and depression symptoms and knee pain in individuals at later recovery time points after ACLR. Previously, Brewer et al⁴ identified an association between pain and negative mood (eg, anxiety, depression, and hostility) over the first 6 weeks of rehabilitation after ACLR, with both pain and negative mood levels gradually declining over time. Other research has also identified high preoperative anxiety as a risk factor for increased postoperative pain and opioid use in the days immediately after surgery.^19,30 This literature suggests that pain in the acute and early recovery period may be influenced by an individual's emotional state both before and after surgery, as well as the individual's proximity to surgery. In contrast, our findings in a sample of individuals who were an average of 5.7 months after ACLR suggest that more severe anxiety and depression symptoms are associated with greater pain at later postsurgical time points. Our post hoc correlation analyses further supported this, revealing moderate to strong relationships between pain and anxiety and depression symptoms among the late recovery group, who were more than 6 months after ACLR. Our identified associations between anxiety and depression symptoms with knee pain among individuals 3 to 12 months after ACLR may be attributed to the middle period of the ACLR rehabilitation process, commonly reported as the period of greatest mental and emotional struggle by patients. A qualitative study by Paterno et al³¹ found that young athletes with ACLR describe the middle phase of rehabilitation as a period of frustration and depression due to feeling functional, yet still unable to return to full activity. Additional studies have found that athletes also tend to exhibit increased anxiety about reinjury and performance during later return-to-sport phases.^7,16 Therefore, it is possible that increased negative mood states commonly experienced during subsequent phases of ACLR rehabilitation may continue to contribute to an individual's pain experience, as highlighted in this study.

Despite significant associations of both anxiety and depression symptoms with more knee pain in our sample, anxiety symptoms accounted for a greater proportion of variance in reported knee pain (25.7%) compared with depression symptoms (15.7%). This difference may be due to the greater number of anxiety symptoms reported by our participants relative to depression symptoms, as well as the distinct characteristics and mechanisms underlying these psychological responses. While the median PROMIS scores of our sample fell below the general US population average PROMIS score of 50,⁴⁰ 30% of our participants reported PROMIS Depression scores above 50, and 48% reported PROMIS Anxiety scores above 50. Increased anxiety symptoms may be more prevalent among our sample of individuals with ACLR due to anxiety's association with a future orientation, as opposed to depression, which is typically associated with a past orientation.¹³ As a result, individuals with depression tend to exhibit a memory bias, characterized by disproportionate retrieval of negative information, whereas individuals with anxiety tend to exhibit an attentional bias marked by increased selective attention to threat-related stimuli.¹³ Given that participants in our sample were an average of 5.7 months after ACLR, it is plausible that individuals at later recovery time points may be more focused on what could be perceived as possible future threats, such as setbacks in recovery, returning to sport, or reinjury, as opposed to negative past events. Additionally, common characteristics of anxiety include increased somatic tension and heightened alertness to external stimuli, as well as internal stimuli such as pain, which can augment its perceived intensity.³⁶ Individuals with ACLR who experience anxiety symptoms may therefore be more likely to selectively attend to internal cues, such as pain, or to external stimuli they perceive as threatening. This increased attentional focus on perceived threats may contribute to the greater proportion of variance in knee pain accounted for by anxiety symptoms in our sample.

Given that elevated pain after musculoskeletal injury increases the risk of chronic pain and disability,³⁸ it is critical to identify psychological symptoms that can influence pain perception early in the recovery process. Validated screening tools, such as the ones used in this study, can be routinely implemented as part of the rehabilitation standard of care to help clinicians identify individuals who may be at risk of experiencing more knee pain throughout ACLR recovery and facilitate timely intervention. To address emotion-related psychological processes that may contribute to an individual's pain experience, such as anxiety and depression, it is recommended to use cognitive-behavioral therapy, relaxation, or positive psychology techniques that promote well-being and positive emotions.²⁶ Among injured athletes, use of cognitive-behavioral therapy-based interventions focused on enhancing psychological well-being has demonstrated improvements in emotional adjustment after injury.³⁵ Additionally, relaxation techniques, such as diaphragmatic breathing, have been shown to improve anxiety and depression among the general population,¹⁸ while the use of positive psychology interventions aimed at increasing self-compassion, positive focus, savoring, and optimism has demonstrated a decrease in anxiety and depression among patients with pain.³² Notably, given the bidirectional relationship between pain and negative mood, treatments directed at reducing negative mood may also help decrease pain. This has been observed among individuals with ACLR, in whom integration of breath-assisted relaxation and imagery interventions has resulted in reductions in both anxiety and knee pain.¹¹ By using techniques that also address pain throughout the ACLR recovery process, individuals may experience greater knee-joint function, improved readiness to return to functional activity, and more positive emotions connected to the injury process.²⁵

Limitations

Our study has several limitations that should be considered. First, as a cross-sectional study, we are unable to make causal inferences about the association of anxiety and depression symptoms with knee pain severity among individuals with ACLR. Future research should utilize prospective cohort or interventional study designs to establish the directionality of this association. Second, outcomes were assessed using self-report instruments, which introduces potential self-report bias, and objective or physiological indicators of pain were not included. Additionally, anxiety and depression symptoms were reported using the PROMIS Anxiety and Depression 4a–Adult v1.0 scales, despite our sample including adolescent participants. Given that pediatric versions of the PROMIS Anxiety and Depression 4a are not available, the adult measures were used to ensure consistency in scores across our sample. However, the adult 4a versions of these questionnaires are written at a reading level appropriate for older adolescents, which is in line with the demographics included in our sample. Similarly, the adult version of the KOOS was used among all participants to ensure consistency in scores across our sample. It is also important to note that the PROMIS Anxiety questionnaire includes an item reflecting somatic symptoms (eg, physiological arousal), which may overlap with injury-related symptoms and potentially inflate anxiety scores in this population. Third, anxiety and depression symptoms were assessed only at a single time point after ACLR, and we are unable to determine if these symptoms were present before ACLR and whether they changed throughout the rehabilitation process. Future research should explore changes in anxiety and depression symptoms throughout various phases of ACLR rehabilitation to identify time points that may be most appropriate for the integration of interventions to address anxiety and depression symptoms. Finally, despite the identified association between anxiety and depression symptoms with knee pain, it is important to acknowledge the amount of variance not accounted for by these factors, which may be due to unmeasured variables, such as variations in rehabilitation protocols or analgesic use. Future research should explore the influence of other biopsychosocial variables that influence pain perception to better understand what may contribute to increased knee pain in individuals with ACLR.

Conclusion

More severe symptoms of anxiety and depression were associated with increased knee pain in individuals 3 to 12 months after ACLR, highlighting the continued influence of psychological factors on pain perception during later stages of recovery. Routine screening for anxiety and depression symptoms throughout the recovery process may help identify individuals at risk of experiencing more knee pain and support the integration of psychological interventions into ACLR rehabilitation.

Footnotes

Final revision submitted March 2, 2026; accepted March 8, 2026.

One or more of the authors has declared the following potential conflict of interest or source of funding: M.S.H. is currently supported by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (grant number K01 AR081389). C.K. is currently a paid consultant for Inova Health in Fairfax, Virginia, USA. S.E.B. is currently supported by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (grant number K23 AR079056).

Ethical approval for this study was obtained from the Michigan State University Institutional Review Board.

ORCID iDs

Francesca M. Genoese

Matthew S. Harkey

Christopher Kuenze

Shelby E. Baez

References

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: DSM-5. American Psychiatric Association; 2013.

Ardern

Webster

Taylor

Feller

JA.

Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. Br J Sports Med. 2011;45(7):596-606.

Betsch

Hoit

Dwyer

, et al. Postoperative pain is associated with psychological and physical readiness to return to sports one year after anterior cruciate ligament reconstruction. Arthrosc Sports Med Rehabil. 2021;3(6):e1737-e1743.

Brewer

Cornelius

Sklar

, et al. Pain and negative mood during rehabilitation after anterior cruciate ligament reconstruction: a daily process analysis. Scand J Med Sci Sports. 2007;17(5):520-529.

Castillo

Wegener

Heins

, et al. Longitudinal relationships between anxiety, depression, and pain: results from a two-year cohort study of lower extremity trauma patients. Pain. 2013;154(12):2860-2866.

Cheng

Downs

Brady

, et al. Interpretation of PROMIS depression and anxiety measures compared with DSM-5 diagnostic criteria in musculoskeletal patients. JBJS Open Access. 2023;8(1):e22.

Clement

Arvinen-Barrow

Fetty

Psychosocial responses during different phases of sport-injury rehabilitation: a qualitative study. J Athl Train. 2015;50(1):95-104.

Cohen

Statistical Power Analysis for the Behavioral Sciences. Routledge; 2013.

Concato

Feinstein

Holford

TR.

The risk of determining risk with multivariable models. Ann Intern Med. 1993;118(3):201-210.

10.

Conley

Stone

Hawk

, et al. Prevalence and predictors of postoperative depression and anxiety after anterior cruciate ligament reconstruction. Cureus. 2023;15(9):e.

11.

Cupal

Brewer

BW.

Effects of relaxation and guided imagery on knee strength, reinjury anxiety, and pain following anterior cruciate ligament reconstruction. Rehabil Psychol. 2001;46(1):28-36.

12.

Evans

JD.

Straightforward Statistics for the Behavioral Sciences. Thomson Brooks/Cole; 1996.

13.

Eysenck

Fajkowska

Anxiety and depression: toward overlapping and distinctive features. Pers Individ Dif. 2018;32:1391-1400.

14.

Filbay

Ackerman

Russell

Crossley

KM.

Return to sport matters—longer-term quality of life after ACL reconstruction in people with knee difficulties. Scand J Med Sci Sports. 2017;27(5):514-524.

15.

Flanigan

Everhart

Pedroza

Smith

Kaeding

CC.

Fear of reinjury (kinesiophobia) and persistent knee symptoms are common factors for lack of return to sport after anterior cruciate ligament reconstruction. Arthroscopy. 2013;29(8):1322-1329.

16.

Forsdyke

Smith

Jones

Gledhill

Psychosocial factors associated with outcomes of sports injury rehabilitation in competitive athletes: a mixed studies systematic review. Br J Sports Med. 2016;50(9):537-544.

17.

Garcia

Park

, et al. Depression symptomatology and anterior cruciate ligament injury: incidence and effect on functional outcome—a prospective cohort study. Am J Sports Med. 2016;44(3):572-579.

18.

Hopper

Murray

Ferrara

Singleton

JK.

Effectiveness of diaphragmatic breathing for reducing physiological and psychological stress in adults: a quantitative systematic review. JBI Evid Synth. 2019;17(9):1855-1876.

19.

Idier

Moussa

Lefèvre

, et al. Preoperative anxiety before anterior cruciate ligament reconstruction is a risk factor of postoperative pain [published online July 7, 2025]. Knee Surg Sports Traumatol Arthrosc.

20.

Kang

Ciminero

Parry

Mauffrey

The psychological effects of musculoskeletal trauma. J Am Acad Orthop Surg. 2021;29(7):e322-e329.

21.

Keefe

France

CR.

Pain: biopsychosocial mechanisms and management. Curr Dir Psychol Sci. 1999;8(5):137-141.

22.

Kolasinski

Neogi

Hochberg

, et al. 2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee. Arthritis Rheumatol. 2020;72(2):220-233.

23.

Krause

Freudenthaler

Frosch

, et al. Operative versus conservative treatment of anterior cruciate ligament rupture: a systematic review of functional improvement in adults. Dtsch Arztebl Int. 2018;115(51-52):855-862.

24.

Nadarajah

Jauregui

, et al. Clinical characteristics associated with depression or anxiety among patients presenting for knee surgery. J Clin Orthop Trauma. 2020;11(suppl):S164-S170.

25.

Lepley

Pietrosimone

Cormier

ML.

Quadriceps function, knee pain, and self-reported outcomes in patients with anterior cruciate ligament reconstruction. J Athl Train. 2018;53(4):337-346.

26.

Linton

Shaw

WS.

Impact of psychological factors in the experience of pain. Phys Ther. 2011;91(5):700-711.

27.

Markatos

Kaseta

Lallos

Korres

Efstathopoulos

The anatomy of the ACL and its importance in ACL reconstruction. Eur J Orthop Surg Traumatol. 2013;23(7):747-752.

28.

Miranda

Viikari-Juntura

Martikainen

Riihimäki

A prospective study on knee pain and its risk factors. Osteoarthritis Cartilage. 2002;10(8):623-630.

29.

Moutzouros

Jildeh

Khalil

, et al. A multimodal protocol to diminish pain following common orthopedic sports procedures: can we eliminate postoperative opioids? Arthroscopy. 2020;36(8):2249-2257.

30.

Nelson

Warren

Xeroegeanes

, et al. Preoperative anxiety differentiates post-surgical opioid use in patients undergoing anterior cruciate ligament reconstruction. J Exp Orthop. 2025;12(3):e70352.

31.

Paterno

Schmitt

Thomas

, et al. Patient and parent perceptions of rehabilitation factors that influence outcomes after anterior cruciate ligament reconstruction and clearance to return to sport in adolescents and young adults. J Orthop Sports Phys Ther. 2019;49(8):576-583.

32.

Peters

Smeets

Feijge

, et al. Happy despite pain: a randomized controlled trial of an 8-week internet-delivered positive psychology intervention for enhancing well-being in patients with chronic pain. Clin J Pain. 2017;33(11):962-975.

33.

Pilkonis

Choi

Reise

, et al. Item banks for measuring emotional distress from the Patient-Reported Outcomes Measurement Information System (PROMIS): depression, anxiety, and anger. Assessment. 2011;18(3):263-283.

34.

Piussi

Berghdal

Sundemo

, et al. Self-reported symptoms of depression and anxiety after ACL injury: a systematic review. Orthop J Sports Med. 2022;10(1):23259671211066493.

35.

Podlog

Heil

Burns

, et al. A cognitive behavioral intervention for college athletes with injuries. Sport Psychol. 2020;34(2):111-121.

36.

Rhudy

Meagher

MW.

Fear and anxiety: divergent effects on human pain thresholds. Pain. 2000;84(1):65-75.

37.

Roos

Lohmander

Ekdahl

Beynnon

BD.

Knee injury and Osteoarthritis Outcome Score (KOOS)—development of a self-administered outcome measure. J Orthop Sports Phys Ther. 1998;28(2):88-96.

38.

Rosenbloom

Khan

McCartney

Katz

Systematic review of persistent pain and psychological outcomes following traumatic musculoskeletal injury. J Pain Res. 2013;6:39-51.

39.

Rousseau

Labruyere

Kajetanek

, et al. Complications after anterior cruciate ligament reconstruction and their relation to the type of graft: a prospective study of 958 cases. Am J Sports Med. 2019;47(11):2543-2549.

40.

Schalet

Pilkonis

, et al. Clinical validity of PROMIS depression, anxiety, and anger across diverse clinical samples. J Clin Epidemiol. 2016;73:119-127.