Tunnel Positioning of Anteromedial and Posterolateral Bundles in Anatomic Anterior Cruciate Ligament Reconstruction: Anatomic and Radiographic Findings

Abstract

Background: The interest in double-bundle anterior cruciate ligament (ACL) reconstructions has recently reawakened. Hypothesis: The center of the femoral posterolateral (PL) bundle and the center of the femoral anteromedial (AM) bundle are not within the same plane and change their orientation throughout passive knee flexion. Additionally, the tibial center of the AM bundle is aligned with the anterior horn of the lateral meniscus and the center of the PL bundle lies at the recommended tibial tunnel position for single-bundle ACL reconstruction reconstruction, 7 to 9 mm anterior to the posterior cruciate ligament. Study Design: Descriptive laboratory study. Materials: In 20 human cadaveric knees (age range, 45–87 years) the distances from the center of the AM and PL bundle to the articular cartilage were measured. Radiographic analyses were performed using the techniques of Bernard and Hertel at the femur as well as the method by Stäubli and Rauschning at the tibia. Results: The center of the AM bundle was at a point 5.3 mm (± 0.7) from the roof of the notch and 5.7 mm (± 0.5) from the intercondylar line. The center of the PL bundle is located at 6.5 mm from the shallow cartilage margin and 5.8 mm from the inferior cartilage margin. On the tibia, the center of the AM bundle is aligned with the anterior horn of the lateral meniscus, while the center of the PL bundle was located 11.2 mm (± 1.2) posterior and 4.1 mm (± 0.6) medial to the anterior insertion of the lateral meniscus. Radiographically, the center of the PL bundle is anterior along Blumensaat's line and lower in the femoral notch along the height of the condyles than the center of the AM bundle. At the tibia, the center of the AM bundle is at 30% and the PL bundle is located at 44% using the method of Stäubli and Rauschning. Conclusion: The center of the femoral PL bundle is shallow and inferior to the AM bundle. On the tibia, the AM bundle lies anterior when compared with the typical single-bundle ACL tunnel that reflects the PL bundle. Clinical Relevance: To imitate the anatomy of the intact ACL, it is mandatory to place the tunnels exactly within the femoral origin and tibial insertion of the ACL.