Avoiding Posterior Cruciate Ligament and Roof Impingement With Transtibial Anterior Cruciate Ligament Reconstruction: Keys to Correct Tunnel Placement

Abstract

Summary: Avoiding posterior cruciate ligament (PCL) impingement, avoiding roof impingement, and replicating the tension pattern of the intact anterior cruciate ligament (ACL) are the keys to successful ACL reconstruction. To avoid PCL impingement, the tibial tunnel should be placed in the coronal plane at an angle between 60° and 65° with the medial joint line, and the lateral edge of the tibial tunnel should pass through the apex of the lateral tibial spine. Placement of the tibial tunnel with these 2 criteria usually requires removal of the medial wall of lateral femoral condyle (ie, wallplasty) until the space between the PCL and lateral femoral condyle exceeds the diameter of the graft by 1 mm. The guidewire should be drilled through the lateral hole in the bullet of the guide and enter the notch midway between the PCL and lateral femoral condyle. To avoid roof impingement without a roofplasty, the tibial tunnel should be customized in the sagittal plane 5 to 6 mm posterior and parallel to the intercondylar roof with the knee in maximum hyperextension, which accounts for variability in roof angle and knee extension. We prefer to use the Howell 65 Degree Tibial Guide to place the tibial tunnel with these criteria in the coronal and the sagittal planes. When the femoral tunnel is drilled through and in line with the correctly placed tibial tunnel, and when the back wall of the femoral tunnel is 1 mm thick, the tension pattern in the graft replicates that of the intact ACL.