Is femoral tunnel length correlated with the intercondylar notch and femoral condyle geometry after double-bundle anterior cruciate ligament reconstruction using the transportal technique? An in vivo computed tomography analysis

Purpose: To analyze femoral tunnel geometry using computed tomography (CT) imaging and evaluate the anatomic factors affecting femoral tunnel length after anterior cruciate ligament (ACL) reconstruction by the transportal technique. Methods: Twenty-nine patients underwent an anatomic double-bundle ACL reconstruction with a femoral tunnel drill by the transportal technique. CT imaging with OsiriX software (version 3.8; Pixmeo, Geneva, Switzerland) was used to measure femoral tunnel length (anteromedial [AM], posterolateral [PL], and central), femoral tunnel divergent angle, and femoral condyle size and intercondylar notch size parameters. Correlations between femoral tunnel length and femoral condyle size and intercondylar notch size parameters were analyzed. Results: The mean AM, PL, and central femoral tunnel lengths were 33.3 ± 3.9 mm, 33.6 ± 3.6 mm, and 34.3 ± 3.2 mm, respectively. A femoral tunnel length of less than 30 mm developed in 7 cases (24.1%) in the AM aspect and 4 cases (13.8%) in the PL aspect. The mean femoral tunnel divergent angle was 14.4° ± 4.1°. A positive correlation was found between AM, not PL or central, femoral tunnel length and medial femoral condyle anteroposterior (AP) distance (P =.01, r = 0.46), lateral femoral condyle AP distance (P =.01, r = 0.43), medial-to-lateral epicondylar distance (P =.03, r = 0.39), middle notch width (P =.009, r = 0.47), notch height (P =.001, r = 0.57), and notch area (P <.001, r = 0.58). Conclusions: After double-bundle ACL reconstruction with the transportal technique through the accessory anteromedial portal, the AM and PL femoral tunnels showed mean tunnel length greater than 30 mm and a divergent angle. However, a femoral tunnel length of less than 30 mm developed in some cases. AM femoral tunnel length was correlated with femoral condyle size (medial femoral condyle AP distance, lateral femoral condyle AP distance, and medial-to-lateral epicondylar distance) and intercondylar notch size (notch width, notch height, and notch area). Level of Evidence: Level IV, therapeutic case series.