Reducing the "killer turn" in posterior cruciate ligament reconstruction

Graft abrasion caused by sharp graft angulation at the graft-tunnel margin of the proximal tibia (the "killer turn") may cause graft failure after posterior cruciate ligament (PCL) reconstruction using the traditional anteromedial route tibial tunnel. One method to reduce the graft angulation is to use the anterolateral route tibial tunnel. However, less acute graft angulation may increase joint translation because of a decrease in graft compressive force. The purpose of this study was to compare the graft angulation and joint translation between anteromedial and anterolateral route tibial tunnels.

Biomechanical study.

Twelve above-the-knee amputation specimens were used in this study. Anteromedial and anterolateral tibial tunnels were made at the desired locations, and the same femoral tunnel was used. Graft angulation was measured by inserting a malleable pin into the tibial and femoral tunnels. Measurements of graft angulation were performed with the knee in extension and in 90 degrees of flexion. The joint translation was measured by the posterior translation of the tibia on the femur at 90 degrees of flexion with a 15-lb posterior force applied to the anterior proximal tibia after PCL reconstruction through the respective tunnels.

The difference in graft angulation between anterolateral and anteromedial route tibial tunnels was statistically significant (P <.001); however, the difference in joint translation showed no statistical significance between the 2 tunnel routes.

The anterolateral route tibial tunnel significantly reduced the sharp graft angulation ("killer turn") at the graft tunnel margin of the proximal tibia, but it did not increase the joint translation as compared with the traditional anteromedial route tibial tunnel. The anterolateral route tibial tunnel is thought to be a better choice when arthroscopic PCL reconstruction is performed with the tunnel technique.