Background

Remnant preservation during anterior cruciate ligament (ACL) reconstruction is controversial. The technique may confer several advantages, but it is unclear whether the stump aids or obscures tibial tunnel positioning

Purpose

The aim of this study was to determine whether the rate of tibial tunnel malposition is influenced by using a remnant preserving technique. The hypothesis was that using a remnant preserving technique to drill entirely within the tibial stump would result in a significant reduction in tibial tunnel malposition as determined by postoperative three dimensional computed tomography (3D-CT).
Study design: Prospective cohort study; Level of evidence, 3.

Methods

Between October 2018 and December 2019, patients undergoing ACL reconstruction underwent surgery with a remnant preserving technique (Group 1) if they had a large stump present (>50% native length of ACL), or underwent stump ablation and utilization of standard landmarks for tunnel positioning (Group 2). Post-operatively, tunnel location was evaluated by 3D-CT using a grid method. Locations were reported in relation to the distance from the center of the aperture of the tunnel to the maximal extents of the grid and expressed as anteroposterior (AP) and mediolateral (ML) percentages of the total grid dimensions. Tunnels were classified as anatomical or non-anatomical based upon the criteria of McConkey et al. Specifically, if the center of the tibial tunnel lay between 30% to 55% from anterior to posterior, and between 40% to 51% from medial to lateral, it was classified as being anatomically placed

Results

52 patients were included in the study (26 in each group). The mean tunnel positions were 36.8 ? 5.5% AP and 46.7 ? 2.9% ML, and in the control group they were 35.6 ? 4.8% AP and 47.3 ? 2.3% ML. There were no significant differences in the mean AP (p=0.134) and ML (p=0.098) tunnel positions between the groups. Inter- and intra-observer reliability varied between fair to excellent, and good to excellent respectively. There was no significant difference in the rate of malposition between groups (group 1, 7.7%; group 2, 11.5%; p=1.000)

Conclusion

Drilling entirely within the ACL tibial stump using a remnant preserving reconstruction technique does not significantly reduce the rate of tunnel malposition determined by post-operative 3D-CT, when compared to stump ablation and utilization of standard landmarks.