Anterior Cruciate Ligament Reconstruction and Mental Health: A Bidirectional Relationship

Background: New-onset mental health (MH) conditions are a concern for patients undergoing anterior cruciate ligament (ACL) reconstruction. Patients with pre-existing MH conditions have been observed to experience poorer postoperative outcomes. Hypothesis: Patients with pre-existing MH diagnoses would report poorer outcomes after ACL reconstruction, and non-sport-related injuries would be associated with a greater incidence of new MH diagnoses. Study Design: Retrospective cohort study. Level of Evidence: Level 3. Methods: Adults undergoing ACL reconstruction between October 2016 and October 2023 at a large university-affiliated practice were included. Patients completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health and Knee Injury and Osteoarthritis Outcomes Score (KOOS) before surgery, and at multiple postoperative timepoints. MH diagnoses included anxiety, depression, bipolar disorder, and other psychiatric conditions documented through medications, International Classification of Diseases, tenth revision codes or chart notes. Continuous and categorical variables were compared using appropriate univariate tests, and mixed-model linear regression was used to compare patient-reported outcomes over time while controlling for patient sex. Results: Out of 365 patients undergoing ACL reconstruction, 50 (13.7%) had a pre-existing MH diagnosis (mean age, 36.42; 84.0% female). Groups did not differ on any scale at baseline except PROMIS Mental Health, which was lower among patients with a pre-existing MH diagnosis (47.3 vs 53.6; P < 0.001). The MH Group reported significantly worse KOOS scores at 2 weeks postoperatively, but no differences were observed thereafter. Among 315 patients without previous history of MH disorder (mean age, 32.90; 52.7% female), 8 (2.5%) developed a new MH diagnosis at 1-year follow-up. Patients aged ≤25 years demonstrated significantly higher baseline KOOS scores than patients >25 years. Among 294 sport-related injuries and 71 non-sport-related injuries, non-sport-related injuries were associated with lower baseline KOOS and PROMIS scores, and higher incidence of new MH diagnoses (7% vs 1.6%; P = 0.02). Conclusion: No differences in KOOS outcomes beyond 2 weeks were found between patients with and without a pre-existing MH condition. Furthermore, non-sport-related injuries were associated with a higher rate of new MH diagnoses. Clinical Relevance: These findings may help clinicians identify patients who could benefit from additional support during recovery.