MRI-based predictive modelling for estimating anterior cruciate ligament injury timing
Author Block: A. Piacentini, K. Abdelmaguid, S. Gitto, S. Fusco, C. Messina, F. Ambrogi, A. Vanzulli, L. M. Sconfienza, D. Albano; Milan/IT
Purpose: Accurate estimation of anterior cruciate ligament (ACL) tear timing is essential for clinical and medico-legal purposes. We aimed to identify MRI parameters linked to lesion chronological age and develop a logistic-regression model to distinguish acute (≤12 weeks) from chronic (>12 weeks) injuries.
Methods or Background: This retrospective study included 426 patients with clinically and MRI-confirmed ACL tears (2014–2024). MRI (1.5/3 T) assessed 11 direct and indirect signs including bone oedema, effusion, tear morphology, ACL atrophy, ACL thinning, "wavy” morphology, anterior tibial translation, angulated posterior cruciate ligament and uncovered lateral meniscus. Firth-penalized logistic regression predicted injury timing; discrimination was assessed by AUC with bootstrap validation (n=200) and a simplified rule-based score was developed for clinical use.
Results or Findings: Among the 426 patients (mean age 35±14 years; 71% male), 261 had acute tears, 73 sub-acute, and 92 chronic. The regression model achieved excellent discrimination between recent and chronic tears with AUC 0.97 (bias-corrected 0.96); at the optimal Youden-index threshold (0.56) it yielded 96% sensitivity, 96% specificity, 96% accuracy, and PPV 0.99. Key discriminators of chronicity were ACL atrophy, thinning, and inhomogeneous thickening. The simplified algorithm–requiring either all major (atrophic ACL, thinned ACL, inhomogeneous thickening of the ACL) or ≥5 minor criteria (bone edema, effusion, uncovered lateral meniscus, full thickness tear with fibers edema, absent wavy ligament, absent anterior tibial translation)–retained high performance (sensitivity 94–96%, specificity 95–96%), closely mirroring the full model.
Conclusion: MRI-based multifeatured analysis accurately distinguishes acute from chronic ACL tears. The simplified rule-based model retains high diagnostic performance and it is practical for routine imaging and medico-legal timing of ACL injuries.
Limitations: Single-center retrospective design; exclusion of clinical variables (age, mechanism of injury) may limit generalizability; the model yields probability estimates rather than a definitive diagnosis.
Funding for this study: No funding received.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Comitato Etico Territoriale Lombardia 1 (RETRO-RAD, CE 61/INT/2017, 12 March 2025).