Does Viewing the ACL Femoral Footprint End on Using a High Medial Portal Produce Better Tunnel Placement as Compared to Viewing it from a Lateral Portal while Drilling: A 3D CT-based Pilot Study.

Abstract

Anatomical placement of an ACL graft is critical to the clinical outcome of an ACL reconstruction. The purpose of the study was to compare the conventional technique of drilling a femoral tunnel from a medial portal while viewing it from a lateral portal versus viewing it from a high anteromedial portal and drilling it from a low medial portal. We hypothesized that the high anteromedial portal possibly provides an end-on view of the tunnel and would lead to a more favourable tunnel position. Sixty patients underwent arthroscopic single-bundle ACL reconstruction with a soft tissue graft. All patients had the same surgeon and same surgical technique (except viewing portal). Each patient underwent a 3D-CT 1-week post-op. We classified the patients into two groups (technique A and B) of 30 each. Postoperative tunnel position in each patient was visualized on CT scan with 3D reconstruction by the quadrant method described by Bernard et al. The distance of the centre of the femoral tunnel from the superior and posterior border of the Bernard frame was obtained in each patient of the two groups and mean value in each group was obtained and compared by Student '<i>t</i>' test at 5% level of significance. The position of the femoral tunnels was also studied in reference to the lateral intercondylar ridge and classified into type I (well placed), type II (moderately malpositioned) and type III (grossly malpositioned). The mean distances in technique A from the posterior and superior border of the lateral femoral condyle was 35.8 ± 8.2 and 35.2 ± 6.7, and in technique B was 38.1 ± 8.6 and 35.8 ± 9.4. The two groups did not differ significantly (<i>P</i> > 0.05) in femoral tunnel position as visualized on 3D-CT scan postoperatively. 53.3% patients had well-placed tunnels (type I) overall with 56.67% of technique A and 50% of technique B in this group. None of the tunnels were grossly malpositioned. The absence of any statistically significant difference between the groups suggests that a high anterolateral portal close to the patellar tendon gives an almost complete view of the lateral aspect of the notch, if not end on. Both techniques produced a majority of well placed (type I) tunnels.