Application of computer-assisted navigation

Abstract

Tunnel malposition is known to be major cause of failure after ACL reconstruction. Three -dimensional fluoroscopic computer navigation has been used to further improve the accuracy of femoral tunnel placement. After a reference frame is securely fixated to the femur, intraoperative image of the distal femur is obtained, which is reconstructed into a 3-D image. During placement of guide pins through far anteromedial portal, navigation guidance allows surgeon to place them inside original attachment area which is located behind resident’s (lateral intercondylar) ridge. The virtual femoral tunnel on the navigation monitor assists surgeon to notice the risk of posterior cortical blowout and the estimated tunnel exit on the lateral femoral cortex. The navigation is also applied to remnant-preserving ACL reconstruction in which anatomical tunnel placement is more challenging because of poor arthroscopic visualization of femoral insertion site. This technology is more powerful in revision ACL reconstruction which is accompanied by several technical challenges such as previous bone tunnels, preexisting implants, or bone defect due to tunnel expansion.