Anatomy of the anterior cruciate ligament insertion sites: comparison of plain radiography and three-dimensional computed tomographic imaging to anatomic dissection

The aim of this study was to provide quantitative data on insertion sites of anterior cruciate ligament (ACL) and to assess the correlation among measurements of anatomic dissection, plain radiographs, and 3D CT images to determine whether radiologic data can accurately reflect real anatomic measurements. Fifteen cadaveric knees were assessed using the three measurement modalities. Lengths of the long and short axis, area, and centre position of each bundle insertion sites by quadrant method were examined on both the femur and tibia. Distances from the insertion centre to distal cortical and posterior cortical margins of condyle on femur, and distance between insertion centres on tibia were also inspected. The average ACL insertion position in the three measurement modalities was at 33.9 % in deep-shallow position and at 26.5 % in high-low position for anteromedial (AM) bundle and at 39.2 and 54.8 %, respectively, for posterolateral (PL) bundle in femur. For tibia, it was at 36.9 % in anterior-posterior position and 47.1 % in medial-lateral position for AM bundle and at 43.1 and 53.5 %, respectively, for PL bundle. The slight differences in various measurements among the three modalities were not statistically significant. The femoral insertion positions were considerably shallow and low, whereas tibial insertion positions were near the average compared to those in previous studies. Plain radiographic and 3D CT measurements showed a reliable correlation with anatomic dissection measurements. The clinical relevance is that plain radiographs rather than 3D CT can be used as a post-operative evaluation tool after ACL reconstruction.