Summary

The aim of this study was to evaluate the relationship of the proximal and posterior limits of the lateral femoral condyle cartilage (point C) with the femoral origin of the ACL.

Abstract

Purpose

The aim of this study was to evaluate the relationship of the proximal and posterior limits of the lateral femoral condyle cartilage (point C) with the femoral origin of the ACL in cadaveric specimens to determine the possibility of using this relationship as an intraoperative anatomical parameter to guide the positioning of the femoral tunnel

Methods

Twenty knees were dissected. The axis of the femoral diaphysis (FD) was first determined, and a parallel line was drawn passing through the most proximal portion of the cartilage of the lateral femoral condyle (point C), generating the X-axis (deep-shallow). A line was plotted perpendicular to this X-axis that passed through point C, creating the Y-axis (low/high). Once these parameters (the X-axis, Y-axis, and point C) were created, the centers of the anteromedial bundle (AM), posterolateral bundle (PL) and ACL (M) were identified. To define the AM, PL, and M points, the ligament was dissected by removing the entire synovium covering the ligament, and the bundles were visually identified. The distances to the center of the anteromedial and posterolateral bands and to the center of the ACL were measured in porcentage.

Results

To obtain the sample number, sample calculation was made, based on the variability of data of a previous pilot study with seven knees. The statistical and nominal errors were taken into consideration for the calculus, and standard deviation of all variables of the pilot sample was determined. Assuming a statistical error of 5% and an error of 45% of the standard deviation (nominal error), the final sample number obtained was of 19 knees. The mean distances were 7.2 mm (SD: 0.7) between the center of the anteromedial bundle and the Y-axis (AM-Y), 9 mm (SD: 1.1) between the center of the ACL and the Y-axis (M-Y), and 12.7 mm (SD: 0.9) between the center of the posterolateral bundle and the Y-axis (PL-Y). Regarding the distance (from point C to the distal cartilage along the X-axis), the center of the anteromedial bundle (AM) was 35% (SD: 4.9%), the center of the posterolateral bundle was 62% (SD: 3.7%), and the center of the ACL (M) was 44% (SD: 7%) of the CD distance on average. Therefore, the AM bundle was above point C, the PL bundle was at or below point C, and the center of the ACL (M) was at or slightly above the level of point C in all cases and was at the same level as point C in 11 of the 20 cases (55%).

Conclusion

Given the similarity among the specimens in terms of the height of the ACL on the Y-axis in relation to the proximal posterior cartilage of the femoral lateral condyle (point C), this point can be used as an arthroscopic intraoperative parameter to define the position of the femoral tunnel in ACL reconstruction for single- or double-bundle techniques.