Impact of Depression on Rehabilitation Outcomes in Pediatric Patients Undergoing ACL Reconstruction: A Retrospective Study

Abstract

Background:

Depression in pediatric populations is rising rapidly and may adversely impact recovery from orthopaedic procedures such as anterior cruciate ligament (ACL) reconstruction. Although the psychological consequences of musculoskeletal injuries have been explored in adults, there remains a gap in understanding how depression affects postoperative outcomes in pediatric ACL patients.

Objective:

This study aimed to evaluate whether depression is associated with differences in postoperative outcomes — including pain, physical function, medication use, and reoperation rates — among pediatric patients undergoing ACL reconstruction.

Methods:

A retrospective cohort study was conducted using the TriNetX Global Collaborative Network. Pediatric patients (18 ​​​​​​years or younger) who underwent arthroscopically assisted ACL reconstruction were divided into 2 cohorts: those with a diagnosis of depression before surgery (ACL + Depression) and those without (ACL − Depression). Propensity score matching was used to control for race and sex. Outcomes assessed during the 6-month postoperative period included pain in the knee, joint stiffness, effusion, gait abnormalities, opioid and nonopioid analgesic use, physical therapy visits, and subsequent ACL reconstruction. Risk ratios, 95% confidence intervals, and P values were calculated.

Results:

After matching, 354 patients were included in each cohort. The ACL + depression group had significantly higher use of nonopioid (21.5% vs. 12.4%, P=0.001) and opioid analgesics (21.8% vs. 13.6%, P=0.004), and higher rates of joint stiffness (17.2% vs. 11.9%, P=0.043) and knee effusion (14.1% vs. 7.6%, P=0.005). Rates of reported knee pain were similar between groups (39.5% vs. 34.5%, P=0.161). A trend toward increased gait abnormalities was observed in the depression group (8.8% vs. 5.1%, P=0.088). Subsequent ACL reconstructions occurred in 2.8% of the ACL + depression group and 0% of the nondepressed group (P=0.001).

Conclusion:

Depression is associated with increased medication use, physical recovery challenges, and higher reoperation rates in pediatric patients following ACL reconstruction, despite similar rates of reported pain. These findings emphasize the need for integrated physical and mental health care during the postoperative period. A multidisciplinary approach — including early mental health screening and support — may improve outcomes in this vulnerable population.

Over the past decade, rates of depression have risen sharply, particularly among pediatric populations. In a national survey of adolescents aged 12 to 17, depression rates had increased from 8.1% in 2009 to 15.8% in 2019.^1,2 These unprecedented rates present a significant challenge in health care. Depression can adversely affect patient outcomes in multiple ways. In one study looking at depression and mortality rates, congestive heart failure patients with depression had nearly double the risk of mortality and experienced poorer emotional and physical outcomes overall.³ In addition, depression has been linked to heightened health service utilization and increased costs, presenting challenges for both individuals and the broader health care system.^4,5 In 2019, the economic burden of major depressive disorder was $333.7 billion, with health care costs being the primary cost driver.⁶

Injuries and major illnesses significantly increase the risk of subsequent depression. According to a report from the Cleveland Clinic, an estimated one-third of people diagnosed with a chronic illness or disease will experience symptoms of depression.⁷ Even if not a chronic illness, injuries like ACL tears may have the same effect. An anterior cruciate ligament (ACL) injury is a common and severe sports-related injury treated through rehabilitation and sometimes surgery. Regardless of the treatment approach, rehabilitation can be both a challenging and lengthy process. Patients may experience negative psychological reactions during their rehabilitation, including anger, grief, lower self-esteem and a diminished sense of belonging.^8–11

Depression is a frequent psychological response to an ACL injury or other acute orthopaedic trauma.¹² Depression has been reported in up to 34% of ACL injuries, while the incidence of depression following a musculoskeletal injury can be as high as 45%, which is much higher than in the general population.^11,12 If these are not properly addressed, they can negatively affect rehabilitation and treatment outcomes, as poor psychological health is associated with worse rehabilitation results after ACL reconstruction.¹³ While documented in adult populations, the association between ACL reconstruction and depression remains unreported in pediatric groups. In addition, existing literature has notable gaps in defining outcomes between individuals with and without depression for ACL reconstruction surgery.

The prevalence of ACL tears in pediatric populations is not clearly defined. Early studies estimated an incidence of 16 per 1000 high school athletes.¹⁴ The incidence of ACL injuries appears to be increasing across pediatric and female athlete populations. Some studies have suggested that year-round sports participation and specialization have contributed to this fact. Females, particularly in sports involving high-impact landings, are at a higher risk than males, being nearly 1.5 times more likely to sustain ACL injuries across adolescent sports.¹⁵ In addition, females face higher risks of mood disorders like depression, which can be exacerbated by psychological challenges during ACL rehabilitation.¹⁰

Our study aims to investigate the relationship between ACL reconstruction and depression diagnoses in pediatric populations, looking specifically at clinical outcomes within 6 months of their surgery. It will compare outcomes such as pain levels, mobility, analgesic use (both opioid and nonopioid), and physical therapy evaluations among those with and without depression. The findings of this study emphasize the importance of both physical and mental health support for enhancing the postoperative experience and long-term well-being of pediatric ACL injuries.

METHODS

This study was reviewed and deemed exempt by the institutional review board as it involved analysis of de-identified, aggregated data. The analysis was performed using the Global Collaborative Network. Data was collected on April 10, 2025. Patient cohorts and outcome measures were defined using Current Procedural Terminology (CPT) and International Classification of Diseases, 10th edition (ICD-10) diagnosis codes.

Two cohorts were defined for this study. Cohort 1 (ACL + depression) included patients aged 18 years or younger who underwent arthroscopically aided anterior cruciate ligament (ACL) reconstruction and had a diagnosis of depression before their ACL reconstruction. Cohort 2 (ACL−depression) included patients aged 18 years or younger who underwent the same ACL procedure but did not have a diagnosis of depression before or after their ACL reconstruction.

For Cohort 1, the query criteria specified demographics with age at most 18 years, a procedure code for arthroscopically aided ACL repair/augmentation or reconstruction (CPT: 29888), and a diagnosis of depressive episode (ICD-10: F32). This query was run on the Global Collaborative Network, with 123 health care organizations (HCOs) responding, resulting in a final cohort of 362 patients. For Cohort 2, the criteria were similar but excluded any diagnosis of depressive episode. This query also involved responses from 123 HCOs, resulting in a final cohort of 7977 patients. The flowchart of patient selection is listed in Figure 1.

FIGURE 1.

Flowchart of patient selection for study cohorts.

The analysis setup required defining the index event, outcome criteria, and the time frame for evaluation. The index event was the first occurrence of the procedure code for ACL repair/augmentation or reconstruction (CPT: 29888), with outcomes analyzed in a time window starting one day after the index event and ending 180 days later. The measure of association analysis calculated and compared the fraction of patients with the selected outcomes, and the risk ratio was recorded. The number of instances analysis calculated the frequency of outcome occurrences within the time window.

Outcomes analyzed included postoperative diagnoses such as pain in the knee, joint stiffness, knee effusion, and abnormalities of gait and mobility, as well as subsequent ACL reconstructions. Medication outcomes included both opioid and nonopioid analgesic use. Depression screening encounters and frequency of physical therapy sessions were also evaluated. Each outcome was assessed to compare postoperative recovery between pediatric ACL reconstruction patients with and without a diagnosis of depression.

To balance the characteristics of the 2 cohorts, propensity score matching was applied, considering race and sex. These were chosen as they are established confounders in depression and orthopaedic outcomes. Outcomes were assessed over a 6-month postoperative period. Statistical comparisons were conducted with significance assessed at α=0.05. Continuous outcomes were compared using 2-sided independent sample t tests, while categorical outcomes were analyzed using z tests to calculate risk ratios and 95% confidence intervals. This structured approach ensured a rigorous comparison of outcomes between pediatric patients undergoing ACL reconstruction with and without a history of depression.

RESULTS

Reviewing the total pediatric database (26,146,809 patients), 303,492 pediatric patients had a documented history of depression. Among those, 372 had undergone ACL reconstruction surgery and were diagnosed with depression. Pediatric patients with previous ACL reconstruction showed a higher overall incidence of depression compared with the general pediatric population in the TriNetX database, with rates of 4.6% versus 1.2%, respectively.

Before propensity score matching, pediatric patients with both depression and ACL reconstruction were significantly more likely to be female (66.0% vs. 44.2%, P<0.001) and White (66.9% vs. 57.7%, P=0.002) compared with those without depression. They were also more likely to be American Indian or Alaska Native (2.8% vs. 0.7%, P<0.001) and Native Hawaiian or Pacific Islander (2.8% vs. 0.7%, P<0.001). Other racial and ethnic groups did not show significant differences (all P>0.05). These differences were controlled for using propensity score matching. After matching, 354 patients were included in each group with no statistically significant differences in sex, race, or ethnicity (all P=1.0). Patient demographics and characteristics before propensity score matching are listed in Table 1.

TABLE 1.

Patient Demographics and Characteristics Before Propensity Score Matching

	Before matching
Category	ACL − Depression (N=7,977)	ACL + Depression (N=362)	P
Male	3940 (49.4%)	107 (29.6%)	<0.001
Female	3528 (44.2%)	239 (66.0%)	<0.001
Unknown sex	195 (2.4%)	10 (2.8%)	0.744
Hispanic or Latino	1255 (15.7%)	57 (15.7%)	0.991
Not Hispanic or Latino	5074 (63.6%)	253 (69.9%)	0.041
Unknown ethnicity	1648 (20.7%)	52 (14.4%)	0.007
White	4598 (57.7%)	242 (66.9%)	0.002
Black or African American	1116 (14.0%)	59 (16.3%)	0.274
Asian	248 (3.1%)	10 (2.8%)	0.668
American Indian or Alaska Native	55 (0.7%)	10 (2.8%)	<0.001
Native Hawaiian or Pacific Islander	57 (0.7%)	10 (2.8%)	<0.001
Other race	586 (7.3%)	19 (5.2%)	0.112
Unknown race	1003 (12.6%)	23 (6.4%)	<0.001

Postoperative outcomes were assessed over a 6-month period. Patients in the ACL+depression group had significantly higher rates of opioid (21.8% vs. 13.6%) and nonopioid analgesic use (21.5% vs. 12.4%), both statistically significant with P=0.004 and P=0.001, respectively. Pain in the knee was common in both groups (39.5% vs. 34.5%; P=0.161).

There were significant differences in effusion of the knee (14.1% vs. 7.6%, P=0.005) and joint stiffness (17.2% vs. 11.9%, P=0.043). Abnormalities of gait and mobility were more frequent in the depression group (8.8% vs. 5.1%), but not statistically significant (P=0.088). Patients in the ACL + depression cohort had an average of 18.1 physical therapy visits, compared with 20.8 in the nondepression group (P=0.058). Although rates of depression screening encounters were low in both groups (2.8%), they were equal (P=1.0). Subsequent ACL reconstructions were documented in 2.8% of the depression group and none in the nondepressed group (P=0.001). Outcomes evaluated over a 6-month period are listed in Table 2.

TABLE 2.

Outcomes Evaluated Over the 6-Month Postoperative Period Comparing the (ACL + Depression) to the (ACL − Depression) Group

Outcome measure	ACL + Depression (n=354)	ACL − Depression (n=354)	Risk ratio	95% CI	P
Nonopioid analgesic use	76 (21.5%)	44 (12.4%)	1.73	1.26-2.38	0.001
Opioid analgesic use	77 (21.8%)	48 (13.6%)	1.60	1.15-2.21	0.004
Abnormalities of gait and mobility	31 (8.8%)	18 (5.1%)	1.72	0.94-3.14	0.088
Pain in knee	140 (39.5%)	122 (34.5%)	1.15	0.95-1.39	0.161
Effusion, knee	50 (14.1%)	27 (7.6%)	1.85	1.18-2.89	0.005
Depression screening encounter	10 (2.8%)	10 (2.8%)	1.00	0.42-2.38	1
Subsequent ACL reconstruction	10 (2.8%)	0 (0.0%)	—	—	0.001
Joint stiffness	61 (17.2%)	42 (11.9%)	1.45	1.01-2.08	0.043
Physical therapy average number of evaluations	20.8	18.1	—	—	0.058

DISCUSSION

In this study, we aimed to investigate the relationship between ACL reconstruction surgery and depression diagnoses in pediatric populations, looking specifically at clinical outcomes within 6 months of their surgery. Pediatric patients with previous ACL surgeries had a higher overall incidence of depression compared with the overall incidence of pediatric depression on the TriNetX database, 4.6% versus 1.2%. In addition, patients with depression diagnoses exhibited statistically significant increases in nonopioid and opioid analgesic use, effusion and joint stiffness, and a trend toward increased abnormalities of gait and mobility with decreased number of physical therapy evaluations, compared with those without depression. Pain in the knee was equally prevalent between groups, suggesting that increased medication usage was not due to higher reported pain incidence. This mismatch between similar reported pain levels and increased analgesic use may reflect differences in provider behavior, patient perception, or under-documentation of subjective pain. We also believe this is an important consideration that, although the pain was not reported to be different, the depressed group was still prescribed more analgesic medication. These findings suggest that depression may be associated with differences in the recovery experience itself rather than severity of pain alone, with implications for both physical rehabilitation and overall care planning.

These trends raise important questions about how depression may not only influence psychological well-being but also interfere with key aspects of postoperative healing and rehabilitation. To date, there is relatively little information regarding the interconnection between ACL reconstruction and mental health in pediatric populations. From this study, pediatric patients with previous ACL surgeries had increased rates of depression compared with the general database, demonstrating a clear need for heightened mental health awareness in our injured pediatric populations. Early support is particularly crucial for young patients, as timely treatment helps them manage their symptoms and supports their emotional and social well-being.¹⁶ The outcomes were evaluated over a 6-month postoperative period. The results indicate that depression significantly impacts several postoperative outcomes.

Although abnormalities in gait and mobility did not reach statistical significance (P=0.088), they were more frequent in the depression cohort and demonstrated a clinically meaningful trend. Depression may hinder the rehabilitation process, potentially due to reduced motivation or increased physical discomfort, which can impede recovery and overall mobility. The depression cohort also exhibited significantly higher rates of knee effusion (14.1% vs. 7.6%) and joint stiffness (17.2% vs. 11.9%), suggesting increased postoperative inflammation or delayed healing. Together, these findings indicate that depression may contribute to physical symptoms that further complicate the recovery trajectory.

Functional recovery also appeared to be affected. Patients in the ACL + depression cohort had an average of 18.1 physical therapy visits, compared with 20.8 in the nondepression group (P=0.058). Although not statistically significant, a reduced median number of visits could influence long-term functional outcomes. Physical therapy is crucial to one’s recovery following ACL reconstruction and has been shown to be critical to both surgical and nonsurgical recovery. It is often considered the most effective intervention to regain strength, range of motion, and patient satisfaction.^17–21

Notably, reoperation rates were higher in the depression group (2.8% vs. 0%, P=0.001), raising concern for either increased reinjury risk, poorer surgical outcomes, or challenges in adherence to postoperative protocols. While the small number of reoperations warrants cautious interpretation, this finding could reflect broader challenges in physical readiness for return to activity or insufficient recovery monitoring. Due to the nature of large database studies, we were unable to assess the context of these repeat surgeries, highlighting a limitation that future work should aim to address.

Interestingly, pain in the knee, though one of the most common outcomes, was reported at similar rates across both groups (39.5% vs. 34.5%, P=0.161). Despite this, patients with depression had significantly higher rates of both opioid (P=0.004) and nonopioid (P=0.001) analgesic use. This mismatch may reflect limitations in administrative coding or underreporting of subjective pain experiences in large data sets. It may also point toward a growing trend in which providers proactively manage pain more aggressively in patients with coexisting mental health diagnoses such as depression. Clinicians may perceive these patients as having lower pain thresholds or an increased risk for chronic pain, leading to more frequent or sustained prescribing of analgesics, even in the absence of documented increases in pain intensity.

This is important to consider in the context of our pediatric populations. Inadequate knowledge regarding pain management can lead to the inappropriate use of analgesics in the pediatric population. In addition, it is critical to investigate whether improper use of pain medication may contribute to long-term health issues, with a particular understanding of how patterns of misuse established during adolescence persist into adulthood.^22–26 Therefore, it is crucial to study the prevalence of pain medication use for musculoskeletal pain in children and adolescents, and this should be a major focus of future studies to determine the most appropriate pain management strategies in this population and the relationship between depression and increased analgesic use found in this study.

Together, these findings suggest that depression in pediatric ACL patients may not only complicate emotional recovery but also contribute to a measurable divergence in physical healing trajectories. They highlight the importance of integrated care approaches that address both physical and mental health aspects to improve overall recovery outcomes. One study found that the psychological state influenced recovery following total joint arthroplasty, with a poor psychological state being negatively related to early postoperative recovery. In addition, at 6 months after operation, anxiety and depression symptoms were correlated with lower satisfaction rates.²⁷ Other studies have discussed the influence of psychological characteristics on maladaptive biochemical and neuroendocrine responses to surgical stress. They found that psychological therapies that modulate patients’ perioperative experiences can positively interact with physiological responses to stress and improve surgical outcomes.²⁸ In either sense, several studies support the importance of mental health care in improving overall recovery and clinical outcomes in injured populations.^27,29–31 Future research should focus on developing and implementing targeted interventions to support mental health in the injured pediatric patient population, potentially improving their postoperative experience and long-term outcomes.

It is also worth acknowledging that many ACL injuries in the pediatric age group are sports-related. Participation in sports is associated with positive mental health behaviors, such as self-confidence, high self-esteem, and strong social support. Student-athletes are often considered to be at a lower risk for mental health problems due to enhanced self-esteem, a sense of belonging, and support from teammates. However, student-athletes are not immune to the effects of depression, especially when their sport may be put on the back burner from a season-ending injury, such as an ACL tear. Thus, it is critically important to consider how the loss of physical identity, routine, and social connectedness can compound the mental health burden and influence clinical outcomes in this population.

While the results of this study are important for understanding our pediatric population, there are several limitations. Using a national de-identified database relies heavily on coded data, affecting the accuracy of diagnoses and symptoms. All data were obtained from 123 participating healthcare organizations (HCOs), and institutional-level clustering may have influenced the observed results. It also makes more subjective measures, such as pain, more difficult to measure. We could not determine the specific indication for analgesic prescriptions, which is a limitation of working with coded administrative data. Further, even though the database includes a national sampling of institutions, the patients in this study may not be representative of the broader population undergoing ACL reconstruction surgery. We could not assess socioeconomic status or institutional distribution across HCOs. However, race and sex were controlled for as confounding factors. Graft choice was also unavailable and represents a limitation, as different graft types may influence outcomes. In this study, patients were not stratified based on the cause of their injuries. Given the heterogeneity of this population, depression may have disproportionately affected outcomes for specific indications. In addition, while we included patients with depression, we could not determine whether their condition was treated, or the timing/severity of diagnosis. These are important variables that future prospective studies should evaluate. Despite these limitations, we believe this study is valuable as the first large national evaluation of the effect of depression on ACL surgical outcomes in our pediatric population.

CONCLUSION

This study highlights a meaningful association between depression and postoperative recovery challenges in pediatric patients undergoing ACL reconstruction. Compared with their nondepressed peers, patients with comorbid depression demonstrated increased reliance on opioid and nonopioid analgesics, higher rates of joint stiffness and knee effusion, and a greater likelihood of subsequent ACL surgeries — all despite reporting similar levels of knee pain. These differences suggest that depression may negatively influence both the physical and psychological dimensions of recovery, potentially through altered pain perception, reduced rehabilitation engagement, or increased inflammation. The findings reinforce the importance of integrating mental health screening, support, and tailored pain management into the standard postoperative care of pediatric orthopaedic patients. A multidisciplinary approach that addresses both psychological and physical recovery may be critical to optimizing outcomes in this vulnerable population. Future research should aim to identify effective interventions that support mental well-being alongside rehabilitation, with a focus on minimizing complications, improving patient satisfaction, and reducing the long-term burden of musculoskeletal injury in youth.