Signal Intensity Ratios and Anatomical Factors as Indicators of Anterior Cruciate Ligament Graft Healing: A 2-Year MRI Study

Background: Prior studies have established that ACL graft healing is a prolonged process, which often lasts up to two years, with the MRI signal intensity ratio (SIR) serving as a key indicator of graft maturity.However, the factors influencing delayed healing, particularly anatomical variation, remain poorly understood.Purpose: To analyze magnetic resonance imaging changes in graft healing 2 years after anterior cruciate ligament reconstruction and identify independent factors associated with poor ACL graft healing.Study Design: Crosssectional study.Methods: A total of 54 patients who underwent ACL surgery and had knee MRI examinations 2 years post-operation were included in the study; graft healing was assessed via MRI signal intensity ratios (SIRs) by dividing the mean graft signal by the PCL signal.The ITK-SNAP software was used to outline the boundaries of both the ACL graft and the fossa intercondylar femur and calculate the area of each layer automatically.Univariate and multivariate logistic regression models were created to evaluate independently correlated factors.Results: The mean SIR in the femoral aperture was significantly greater than that in the tibial aperture (3.70 1.05 vs 2.70 0.83, respectively, P = 0.001).Univariate regression analysis revealed several factors significantly associated with the proximal graft SIR, including a small fossa intercondylar femur (P = 0.001), a larger graft size (P = 0.033), and a large LCAPD/PTAPD ratio (P = 0.026).Multivariate regression analysis revealed two significant factors: the LCAPD/PTAPD ratio, which was associated with the proximal graft SIR (P = 0.009), and the femoral aperture graft SIR (P = 0.005), and the fossa inter-