Anterior Cruciate Ligament Insertions on the Tibia and Femur and Their Relationships to Critical Bony Landmarks Using High-Resolution Volume-Rendering Computed Tomography

Background: Controversy exists regarding the locations of the anterior cruciate ligament insertions on the femur and tibia and visualization of these insertions during surgical reconstruction. Hypothesis: Anatomical insertions of the anterior cruciate ligament have relationships to bony landmarks of the tibia and femur. Study Design: Descriptive laboratory study. Methods: Eight cadaveric knees were scanned by computed tomography, reconstructed 3-dimensionally, and examined from simulated arthroscopic, sagittal, and axial perspectives. Volume-rendering software was used to document the relationship of the anterior cruciate ligament to the bony anatomy. Results: A bony ridge (Resident's Ridge) at the anterior border of the anterior cruciate ligament was readily noted on the medial wall of the lateral femoral condyle. Superiorly, anterior cruciate ligament fibers inserted up to the roof of the notch and to 3 to 3.5 mm of the articular surface posteriorly and inferiorly. The anterior cruciate ligament inserted into a fovea anterior to the tibial eminence. Posteriorly, anterior cruciate ligament fibers inserted up to a ridge between the medial and lateral intercondylar tubercles. Medially, anterior cruciate ligament fibers inserted onto the ridge at the lateral border of the medial tibial condyle. There was no distinct anterior or lateral bony border with anterior cruciate ligament fibers blending into the anterior horn of the lateral meniscus. Conclusion: The anterior border of the femoral anterior cruciate ligament origin is Resident's Ridge. The ridge between the medial and lateral intercondylar tubercles at the base of the tibial eminence is the posterior margin of the anterior cruciate ligament on the tibia. Clinical Relevance: Bony landmarks can be used to aid in anatomical anterior cruciate ligament reconstruction.