Anatomy of the anterior cruciate ligament: Three-bundle concept with an apparent twist – A cadaveric study

Objectives: A nonanatomical anterior cruciate ligament reconstruction leads to delayed quadriceps recovery, rotational instability and early osteoarthritis. Despite advances in our knowledge of ACL, there remains a lack of clarity in accurately identifying the anatomical ACL footprint, especially on the femur. This study aims to clarify the confusion among surgeons. Materials and Methods: Data were collected from 19 cadaver knees. The dissection of cadaver knees allowed for a detailed examination of the ACL footprints, including their orientation and measurements. Results: ACL is a 3-bundle structure with distinct footprints on the femur and tibia. The femoral footprint is on the lateral intercondylar resident’s ridge (RR). Anteromedial (AM) bundle arises posterior to the anterior horn of the medial meniscus, from the lateral aspect of the medial tibial spine and attaches to the posterosuperior part of RR. Anterolateral (AL) (intermediate bundle) arises mainly from the medial aspect of the lateral tibial spine and attaches to the middle of RR. Posterolateral bundle arises posterior AL and 3 mm AM to the lateral meniscal posterior root and attaches anteroinferior on the RR. Conclusion: ACL is a triple-bundle structure; each bundle has different lengths and distinct footprints on both the femur and tibia. The femoral footprint is located on the RR. Each bundle travels in a straight path from the tibia to the femur, and there appears to be a twist in the ACL during flexion, although no actual twist occurs due to the unique attachments on the femur and tibia.