Preoperative Revision Anterior Cruciate Ligament Reconstruction Tunnel Evaluation Using Curved Planar Reformation: The Waterslide Technique

To describe a novel computed tomography (CT)–based reconstruction technique using curved planar reformation (CPR) for in-plane visualization of anterior cruciate ligament (ACL) reconstruction tunnels to aid in revision surgical planning. Standard diagnostic CT scans in patients with prior ACL reconstruction are postprocessed using a CPR-based reconstruction. A centerline is generated through the femoral and tibial tunnels, and perpendicular reconstructions produce sequential short-axis images along the tunnel course. The described technique generates oblique axial images aligned with the native tunnel trajectory, allowing continuous visualization of tunnel morphology along its full length. This “waterslide” view enables assessment of tunnel diameter, shape, and orientation in a single continuous imaging sequence. The waterslide technique is a CT postprocessing method that provides in-plane visualization of ACL reconstruction tunnels and may facilitate assessment of tunnel morphology during preoperative evaluation for revision ACL reconstruction. Level of evidence: technical note.