Quantitative Evaluation of Transtibial Aiming Accuracy in Anterior Cruciate Ligament Reconstruction

Background Precise femoral tunnel placement is a critical determinant of anterior cruciate ligament (ACL) reconstruction success. This study aimed to evaluate the accuracy of transtibial aiming in relation to a predrilled anatomic femoral tunnel using radiographic and intraoperative photographic measurements. Methodology In total, 43 single-bundle ACL reconstructions with hamstring autografts were analyzed. After drilling the femoral tunnel through the anteromedial portal, a 4-mm offset guide was inserted transtibially toward its center. Tibial tunnel angles were measured in coronal and sagittal planes, and the absolute distance (D) between the centers of the femoral tunnel and the transtibial K-wire was recorded. A normalized index (I = D/radius, R) was calculated, with I <1 indicating that the transtibial wire remained within the tunnel perimeter. Results The mean femoral tunnel diameter was 7.44 mm (R = 3.72 mm), mean D was 4.50 mm (1.75-6.85 mm), and the overall mean index was 1.2. For tunnels of 7.0 and 7.5 mm, the mean index exceeded 1, while for tunnels of 8.0-9.0 mm, it was less than 1. Deviation showed no correlation with tibial tunnel angulation. In no case did the transtibial K-wire reach the exact femoral center. Conclusions The findings of this study demonstrated that transtibial aiming lacks sufficient precision for anatomic femoral tunnel placement, supporting the anteromedial portal approach as the more accurate technique.