Anteromedial Portal Versus Outside-In Technique for Creating Femoral Tunnels in Anatomic Anterior Cruciate Ligament Reconstructions

Abstract

To determine whether the anteromedial (AM) portal and outside-in techniques in anterior cruciate ligament reconstruction differ (1) in the coronal femoral tunnel position, (2) in the femoral tunnel length, and (3) in the incidence of femoral tunnel-related complications, such as femoral socket blowout. We examined 63 knees undergone primary anterior cruciate ligament reconstructions using the AM portal technique (AM portal group) and 54 knees using the outside-in technique (outside-in group). Coronal femoral tunnel positions between the 2 groups were assessed on postoperative tunnel-view radiographs and compared. Comparisons of femoral tunnel lengths, proportions of knees with a femoral tunnel length of less than 30 mm, and incidences of femoral tunnel-related complications were performed between the 2 groups. There were no significant differences in coronal femoral tunnel positions between the AM portal and outside-in groups (56.6° v 56.4°, P > .99). Differences in femoral tunnel lengths between the AM portal and outside-in groups did not reach statistical significance (37.6 mm and 39.0 mm, respectively; P= .097), but the tunnel length of the outside-in group showed smaller variation than that of the AM portal group in terms of standard deviation (2.7 v 6.0). In addition, the AM portal group had a significantly greater proportion of knees with a femoral tunnel length of less than 30 mm than the outside-in group (14% v 0%, P= .004). There were 2 tunnel-related complications (3%) (highly suspicious cortical blowouts) in the AM portal group and none in the outside-in group (P= .499). This study shows that compared with the AM portal technique, the outside-in technique can achieve a similar femoral tunnel position in the coronal plane with a reduced chance of a femoral tunnel length of less than 30 mm. Level IV, therapeutic case series.