Real-time indocyanine green perfusion assessment demonstrates regional vascularity and loss of perfusion in the anterior cruciate ligament during knee arthroscopy.

Purpose: To evaluate the feasibility of real-time intra-articular indocyanine green (ICG) fluorescence imaging for visualising anterior cruciate ligament (ACL) vascularity during knee arthroscopy and to explore perfusion patterns associated with ligament integrity. Methods: In this prospective exploratory study, patients undergoing knee arthroscopy with informed consent were consecutively enrolled. ICG perfusion assessment was performed without tourniquet use using near-infrared arthroscopic imaging. A single intravenous bolus of ICG was administered, and fluorescence dynamics were recorded. In primary ACL rupture cases, fluorescence at the torn stump was assessed qualitatively as present or absent. In ACL-intact knees without advanced osteoarthritis, quantitative region-of-interest-based analysis was performed to compare medial and lateral perfusion within the ligament. Paired comparisons were conducted using the Wilcoxon signed-rank test. Results: Thirty-two knees underwent ICG perfusion assessment. Fluorescence was successfully visualised in all cases, and no ICG-related complications were observed. All primary ACL rupture cases demonstrated absence of fluorescence at the torn stump, indicating loss of local perfusion. In ACL-intact knees ( Conclusion: Real-time intra-articular ICG fluorescence imaging is feasible during routine knee arthroscopy and enables visualisation of ACL vascularity. Distinct perfusion patterns associated with ligament integrity were observed in this exploratory cohort. These findings provide preliminary biological insight into intra-articular microcirculation and establish a foundation for future outcome-oriented studies. Level of Evidence: Level IV.