Location of the Anatomic Footprint Centers of the Anterior Cruciate Ligament Determined by Quadrant Method on Three-Dimensional Magnetic Resonance Imaging.

Background: The quadrant method is widely used to determine the femoral footprint center (FFC) on radiographs or computed tomography (CT) and can also describe the tibial footprint center (TFC). However, its application on three-dimensional (3D) magnetic resonance imaging (MRI) has been limited. This study aims to describe the ACL footprint center position on 3D MRI of healthy knees using the quadrant method. Methods: Proton density (PD) sequence 3D MRI was conducted on 45 intact knees, aged 18 to 45 years. The centers of the ACL footprints were determined, and 2D simulated radiographic images were generated from the 3D MRI data. The quadrant method was then applied to calculate the positions of the footprint centers. Results: The FFC was located at 31.6% in the deep-shallow (DS) direction and 31.3% in the high-low (HL) direction. The TFC was positioned at 45.1% in the mediolateral (ML) direction and 39.9% in the anteroposterior (AP) direction. Conclusions: The ACL footprint centers identified in this study were positioned similarly to previous studies, with the exception of the TFC in the ML direction, which was found to be more medial. This approach has the potential to enhance preoperative planning and intra-operative navigation in ACL reconstruction surgeries.