Radiologic evaluation of the insertion sites of the 2 functional bundles of the anterior cruciate ligament using 3-dimensional computed tomography.

Background: Anterior cruciate ligament reconstruction with a double-bundle technique requires exact tunnel positioning. Reference values for the anatomic insertions are necessary for radiographic intra- and postoperative control and fluoroscopy-based navigation.

Hypothesis: The femoral and tibial insertions of the anteromedial bundle (AMB) and posterolateral bundle (PLB) of the anterior cruciate ligament can be described using standardized computed tomography scans.

Study Design: Descriptive laboratory study.

Methods: The insertion sites of the AMB and PLB were macroscopically identified and tagged by copper wire in 12 specimens. Computed tomography scans with predefined reconstructions were performed. Femorally, the geometric center of the insertions were determined in the sagittal view and described in a deep-high 10 x 10 grid. Tibially, the insertions were described as the ratio between the geometric center of the insertion sites with respect to the mediolateral and sagittal diameter of the tibia in frontal and sagittal reconstruction, respectively. The tibial insertions were described using a 10 x 10 grid in axial orientation.

Results: The geometric midpoints of the insertion areas at the femur of the AMB and PLB were located on the reticule at x = 21% + or - 3% and y = 22% + or - 2% for the AMB and x = 27% + or - 3% and y = 45% + or - 3% for the PLB. In the sagittal plane, the center of the tibial insertion was located at 41% + or - 3% and 52% + or - 3% of the tibial diameter from the anterior border for the AMB and PLB, respectively. The geometric centers of the tibial insertions in axial view were x = 52% + or - 2% and y = 37% + or - 3% for the AMB and x = 50% + or - 2% and y = 48% + or - 3% for the PLB.

Conclusion: The insertion site characteristics of the AMB and PLB can be evaluated by predefined reconstructions of computed tomography scans. Clinical relevance These results can serve as orientation landmarks for intra- and postoperative radiographic control and fluoroscopic-based navigation.