Summary

Because of variation in each surgeon and inter-surgeon, it is necessary to make an effort to reduce variability and build an objective system for accurate femoral entry position using transportal technique in ACL reconstrucion

Abstract

Introduction

Anatomical reconstruction is known to be an effective way to reproduce the original ACL femoral insertion. Several studies have reported that the position of tunnel can be more anatomically made when using the transportal technique; therefore, anatomical reconstruction using transportal technique has been recently performed a lot in ACL reconstruction. However, when performing anatomical reconstruction, there is no precise guideline for knee flexion angle when performing femoral tunnel drilling, as well as a lack of objective guiding system for tunnel entry avoiding the destruction of posterior cortex. Therefore, there is a high possibility that portal entry is not located at the planned same position. The purpose of this study was to compare the femoral tunnel entry between two surgeons using the same surgical technique, and to figure out the variability of tunnel entry.

Methods

One hundred patients (100 knees), who underwent arthroscopic anatomical ACL reconstruction using transportal technique by two different orthopedic surgeons from 2010 to 2018, were included. For all patients, 3D computed tomography were taken after ACL reconstruction and reconstructed using Mimics program. Bernard's quadrant method was used to measure the femoral tunnel entry. Variability in one surgeon and the mean value between the two surgeons were compared using an independent two-sample t-test.

Result
Although the mean value of relative depth of femoral tunnel from posterior wall (28.52% vs. 27.12%) and the relative height of femoral tunnel from Blumensaat line (24.51% vs. 26.09%) were not significantly different between two surgeons, the height difference from Blumensaat line (1.5%) was greater than the difference in depth from posterior wall (1.3%) (p <0.04). The range of measured values measured by standard deviation is quite wide, with the values from posterior wall to femoral tunnel in each surgeon being 28.52±5.11 vs. 27.12±3.92%, and those from Blumensaat line to femoral tunnel in each surgeon being 24.51±7.29 vs. 26.09±5.82%. These results show that the range of relative height of the femoral tunnel from inferior femoral condyle was greater. Although there was no significant difference in the mean value of femoral tunnel entry, variability in each surgeon was measured as being large.

Conclusion

Although anatomical femoral tunnel entry is located at the closest position to surgeon’s planning using transportal technique, variability is present in each surgeon in addition to inter-surgeon variability. Therefore, it is necessary to make an effort to reduce variability and build an objective system for accurate femoral entry position.