Comparisons of femoral tunnel position and length in anterior cruciate ligament reconstruction: Modified transtibial versus anteromedial portal techniques

Purpose: We aimed to compare the modified transtibial and anteromedial (AM) portal techniques of anterior cruciate ligament reconstruction with respect to femoral tunnel position and length, as well as to identify factors associated with tunnel length. Methods: After exclusions, 105 primary anterior cruciate ligament reconstructions (55 in transtibial group and 50 in AM portal group) were studied. Femoral tunnel positions were assessed on postoperative tunnel-view radiographs, and tunnel lengths were measured during surgery. Differences between femoral tunnel positions in the coronal plane and lengths in these 2 groups were examined, and factors associated with tunnel lengths were investigated. Results: The AM portal group had a significantly more oblique femoral tunnel position than the transtibial group. However, femoral tunnels in the AM portal group were substantially shorter than tunnels in the transtibial group (34.2 v 43.3 mm, P <.001); the proportions of knees with femoral tunnels measuring less than 30 mm in the AM portal and transtibial groups were 26% and only 2%, respectively. In addition, a more oblique femoral tunnel position and a shorter distal femur mediolateral width were found to be significantly associated with a shorter femoral tunnel. Conclusions: This study shows that the AM portal technique can achieve a more oblique femoral tunnel position but that resultant tunnels are substantially shorter than tunnels produced by the modified transtibial technique. Level of Evidence: Level IV, therapeutic case series.