Accuracy of femoral tunnel placement and resulting graft force using one- or two-incision drill guides. A cadaver study on ten paired knees

Abstract

Recently, one-incision drill guides introduced through predrilled tibial tunnels have become popular in anterior cruciate ligament (ACL) reconstruction. No data are available on the reproducibility of the tunnel placement when this drill guide is used. The primary goal of this study was to compare accuracy of tunnel placement using the one-incision (all-inside) and the conventional two-incision drill guide (outside-in) to the location of the center of the normal ACL attachment. Furthermore, our goal was to measure the forces seen by the normal ACL during extension from 90 degrees of flexion, when the tibia is subjected to 100 N anterior load (22.7 lbs), and compare these with the forces measured in the reconstructions performed with the two drill guides. The center of the tunnel on the lateral femoral condyle using the two different drill guides was measured with a three-dimensional pointer and compared with the center of the normal ACL insertion site. Forces in the normal ACl and the reconstructed ligament were measured with a buckle transducer in a loaded and an unloaded state at four different flexion angles. The one-incision drill guide led to a statistically more proximal placement of the graft than both the conventional drill guide and the center of the normal ACL. Both drill guides led to an anterior placement compared with the normal ACL. There was no difference in the graft forces after reconstruction with the two drill guides, but the forces in the loaded grafts were twice those of the normal ACL.