Stability evaluation of single-bundle and double-bundle reconstruction during navigated ACL reconstruction.

Recently, anatomic double-bundle anterior cruciate ligament (ACL) reconstructions, which reproduce the anteromedial and posterolateral bundles, have been developed to improve knee laxity. However, there are little data on the in vivo biomechanics after such reconstructions. In this paper, we will review biomechanical and clinical studies that have compared single-bundle and double-bundle reconstruction, and introduce our intraoperative evaluation of double-bundle reconstruction using a navigation system. In the navigation evaluation, knee kinematics before and after ACL reconstruction were assessed, and functions of the anteromedial and posterolateral bundles were evaluated. Although the posterolateral bundle has an important role in the knee extension position, the anteromedial bundle improved knee laxity during the more knee flexion positions. Furthermore, double-bundle reconstruction improved knee laxity compared with either posterolateral or anteromedial bundle reconstruction throughout knee range of motion. Although traditional single-bundle reconstruction, reproducing the anteromedial bundle, is a reasonable procedure, double-bundle reconstruction has the potential to improve knee stability after ACL reconstruction.