Summary

This is the first study in the literature that aim to evaluated the accuracy of using the most proximal and posterior portion of the lateral femoral condyle cartilage for positioning the femoral tunnel over the anteromedial bundle.

Abstract

Purpose

The objective of the study is to evaluate the accuracy of femoral tunnel positioning in the anatomical reconstruction of the anteromedial bundle of the ACL using the most proximal and posterior portion of the lateral femoral condyle cartilage (Point C), as described by Cury et al. This is the first study in the literature that aim to evaluated the accuracy of this technique in vivo for positioning the femoral tunnel over the anteromedial bundle.

Methods

From december 2022 to december 2023, 47 patients underwent ACL reconstruction using Point C as an anatomical landmark for anteromedial bundle reconstruction. To creat the femoral tunnel, a femoral guide, using the outside-in technique, through the anterolateral portal measuring from Point C to the anterior edge of the femoral condyle, generating the XY distance. From the posterior limit of the XY distance, a value equivalent to 35% of XY is measured, from posterior to anterior, which represents the sagittal coordinate. From this coordinate, a point 2 mm proximal is marked with radiofrequency or ice pick through the anteromedial portal, identifying the center of the native AM bundle of the ACL. From this coordinate, the guide is used to pass the guide wire and finally, the femoral tunnel is created. After the procedure, the pacient underwent tomographic evaluation, to obtain a true side view of the knee after tridimensional reconstruction. To assess the accuracy of the positioning, we used Bernard's quadrants. Two evaluators at three different time measured the percentages for each case, and the results were compared to the values described in the literature for the anteromedial bundle (horizontal coordinate/depth = 24.2 ± 4% and vertical/height coordinate = 21.6 ± 5.2%).

Results

Intraoperatively the average distance from Point C to the anterior portion of the lateral femoral condyle was 23.3 mm, and the average correlation value of Point C with the center of the anteromedial bundle in the horizontal coordinate intraoperatively was 7.68 mm. After CT evaluation, using Bernard’s quadrants, the average depth values (X coordinate) for evaluator 1 at time 1 were 23.63%, and at time 2 were 23.62%. The average height values (Y coordinate) at time 1 were 22.7%, and at time 2 were 22.07%. The analysis by the second evaluator at the third time point had an average X coordinate of 23.56% and Y coordinate of 22.34%. A statistical significance level of 0.05 was set for this analysis. To determine significance between the responses for the calculated prevalences, the Z-test for two proportions was used. The sample power was calculated to be 0.825, which is considered excellent, as it is above 0.80. The accuracy for height was 100% in all three measurements. In depth, the values ranged from 91.5% to 93.6%.

Conclusion

The technique showed good accuracy in mimicking the anteromedial bundle in the femoral tunnel during ACL reconstruction and can be used as an anatomical parameter to guide the surgeon while perfoming the surgery.