Abstract
BACKGROUND: Fear of pain and reinjury significantly hinders return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). However, the neural basis of this psychological barrier remains unclear. HYPOTHESIS: ACLR patients will exhibit structural and functional brain changes in regions related to pain and emotion, influencing their psychological readiness to RTS. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: We recruited 36 ACLR patients and 36 healthy controls, collecting visual analog scale (VAS) scores for knee pain, Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scores, and structural and functional magnetic resonance imaging data. RESULTS: Significant smaller gray matter (GM) volume was observed in the thalamus (effect size, -0.813), periaqueductal gray (PAG) (effect size, -0.737), and prefrontal cortex (PFC) (effect size, -0.690) in ACLR patients. We also found weakened functional connectivity between the PAG and the anterior cingulate cortex (ACC). GM volume in the thalamus was correlated positively with ACL-RSI scores (r = 0.362). Notably, the effect of VAS scores on ACL-RSI was mediated by the reduced FC between PAG and ACC (direct effect, -2.071, indirect effect, -0.826). CONCLUSION: This study reveals that the psychological readiness to RTS after ACLR may be due to peripheral nociceptive input causing changes in pain-related brain structures and functions. CLINICAL RELEVANCE: Recognizing these neuropsychological changes may guide comprehensive rehabilitation strategies post-ACLR, emphasizing the need for interventions targeting central neural mechanisms alongside physical recovery.