Morphology of the tibial insertion of the posterior cruciate ligament.

BACKGROUND It has been demonstrated that double-bundle reconstruction of the posterior cruciate ligament restores knee kinematics better than does single-bundle reconstruction. The objective of this study was to identify the tibial insertion site of the posterior cruciate ligament and the related osseous landmarks to help guide surgeons in the performance of an anatomical double-bundle reconstruction of the posterior cruciate ligament. METHODS Twenty-one unpaired human cadaver knees were evaluated. The geometric data and surface features of the tibial insertion site of the posterior cruciate ligament and its bundles were studied with macroscopic observation and with three-dimensional laser photography. RESULTS The mean surface areas (and standard deviations) of the anterolateral and posteromedial insertion sites were 93.1+/-16.6 mm2 and 150.8+/-31.0 mm2, respectively, and the distance between their centers was 8.2+/-1.3 mm. The mean length and width of the anterolateral insertion site were 7.8+/-1.5 mm and 9.2+/-1.6 mm, and the mean length and width of the posteromedial insertion site were 9.4+/-1.4 mm and 15.0+/-2.7 mm. The average distances from the anterior and medial margins of the tibial plane to the center of the anterolateral insertion, defined as percentage ratios of the anteroposterior and mediolateral dimensions, were 83.4%+/-3.4% and 47.1%+/-1.9%, respectively, and the average distances from the anterior and medial margins of the tibial plane to the center of the posteromedial insertion were 95.5%+/-1.9% and 43.8%+/-2.2%. A notable change in angle, of >10 degrees, was observed between the anterolateral and posteromedial slopes in sixteen of the twenty-one knees. The average angle between the anterolateral and posteromedial slopes was 14.5 degrees+/-6.4 degrees. CONCLUSIONS The tibial insertion site of the posterior cruciate ligament and its bundles is very complex. However, the shapes and positions of the insertion sites of the two bundles are consistent in that they are located in different planes on the posterior intercondylar fossa. We noted a consistent change in slope between the tibial insertion sites of the anterolateral and posteromedial bundles.