Abstract: Objective To investigate whether femoral tunnel positioning during anterior cruciate ligament reconstruction （ACLR） modulates early postoperative brain functional plasticity. Methods In this study, 18 patients with unilateral left-knee anterior cruciate ligament rupture were enrolled between February 2022 and February 2024 and received postoperative CT-based 3D reconstruction quantified femoral tunnel position. The patients were categorized into a normal position （G1, n=9） and an anteriorly deviated （G2, n=9） groups. Ten healthy volunteers served as controls （HC）. Baseline and clinical data were recorded. Resting-state functional MRI （rs-fMRI） was acquired at 8-12 weeks postoperatively. Amplitude of low-frequency fluctuation （ALFF） was calculated and compared across groups. Results Baseline characteristics and early postoperative clinical outcomes were comparable among the three groups （P>0.05）. No significant ALFF differences were observed between G1 and G2 （P>0.05）. Compared with HC, both surgical groups exhibited increased ALFF in the right frontal cortex, bilateral temporal lobes, and posterior lobes of left cerebellum. Notably, G2 demonstrated more focal activation in the Frontal_Med_Orb_R and Cerebelum_8_L, accompanied by decreased ALFF in the Precentral_R, SupraMarginal_R, and Lingual gyrus （P<0.05）. Conclusion Early after ACLR, femoral tunnel positioning differences do not significantly alter the predominant pattern of cortical functional plasticity, characterized by frontal-temporal-cerebellar hyperactivation. However, it induces region-specific suppression in G2, indicating impaired fine motor control. These findings support incorporating femoral tunnel positioning and brain region activation signals into personalized neuro-rehabilitation strategies to provide new ideas for the precise treatment of ACLR.

Key words: Anterior cruciate ligament reconstruction, Femoral tunnel positioning, Brain plasticity, Amplitude of low-frequency fluctuation, Motor control