Lower anatomical femoral ACL tunnel can be created in the large volume of femoral intercondylar notch

Purpose The purpose of this study was to investigate the correlation between femoral intercondylar notch volume and the characteristics of femoral tunnels in anatomical single bundle anterior cruciate ligament (ACL) reconstruction. Methods Fifty-one subjects (24 male and 27 female: median age 27: range 15-49), were included in this study. Anatomical single bundle ACL reconstruction was performed in all subjects using a trans-portal technique. Femoral tunnel length was measured intra-operatively. Three-dimensional computed tomography (3D-CT) was taken at pre and post-surgery. The intercondylar notch volume was calculated with a truncated-pyramid shape simulation using the pre-operative 3D-CT image. In the post-operative 3D-CT, the modified quadrant method was used to measure femoral ACL tunnel placement. Results Femoral tunnel placement was 47.6 +/- 10.5% in the high-low (proximal-distal) direction, and 22.6 +/- 5.4% in the shallow-deep (anterior-posterior) direction. Femoral tunnel length was 35.3 +/- 4.4 cm. Femoral intercondylar notch volume was 8.6 +/- 2.1cm(3). A significant correlation was found between femoral intercondylar notch volume and high-low (proximal-distal) femoral tunnel placement (Pearson's coefficient correlation: 0.469, p = 0.003). Conclusion Femoral ACL tunnel placement at a significantly lower level was found in knees with large femoral intercondylar notch volume in the trans-portal technique. For the clinical relevance, although the sample size of this study was limited, surgeons can create femoral ACL tunnel low (distal) in the notch where close to the anatomical ACL footprint in the knees with large femoral intercondylar notch volume.