Rethinking the Prognostic Value of the Lateral Femoral Notch in ACL Rehabilitation: A Longitudinal Cohort Study on Natural Remodeling and Patient Outcomes

Background The lateral femoral notch (LFN) sign, a footprint of tibiofemoral impaction, is recognized indicator of nterior cruciate ligament (ACL) injury. However, its potential for spontaneous osseous remodeling after reconstruction has yet to be established, precluding evidence-based patient counseling regarding its prognosis. Methods This retrospective multi-timepoint cohort study ( from July 2017 to January 2025), patients who underwent ACL reconstruction (ACLR) and received 3.0-T MRI at baseline (≤ 30 days post-injury) and one postoperative time point (1, 2, or 5 years) were included. Patients were allocated to three cohorts based on their single follow-up MRI: 1-year cohort (n = 38), 2-year cohort (n = 27), and 5-year cohort (n = 37). Inclusion criteria were sports-related injury and an MRI obtained within 30 days post-injury. The maximal depth of the LFN was measured on sagittal MRI. Results The depth of the LFN decreased significantly from preoperative values at 1 year (0.70 ± 0.30 mm, P < .001), 2 years (0.55 ± 0.26 mm, P < .001), and 5 years (0.46 ± 0.19 mm, P < .001) postoperatively. The change in LFN depth between 1 and 5 years was significant (P < .001), but the rate of change from 1–2 years did not did not differ significantly from that of the 2–5 years interval. LFN depth was significantly associated with age (r = -0.276, P = .005), Body mass index (BMI) (r = 0.312, P = .001), and injured side (r = 0.222, P = .025). Changes in LFN depth were significantly associated with gender (r = 0.215, P = .030) and injured side (r = -0.207, P = .037). Conclusion The LFN sign exhibits significant spontaneous osseous remodeling over 5 years post-ACLR. These findings provide crucial evidence for clinicians to manage patient expectations, alleviate kinesiophobia by demonstrating the dynamic nature of this lesion, and consider personalized rehabilitation strategies based on individual factors like gender and injured side.