What Kinds of Posterior Cruciate Ligament Bundles Are Preserved in Cruciate-Retaining Total Knee Arthroplasty? A Three-Dimensional Morphology Study

In this study, the effects of tibial bone cutting on the attachment area of the posterior cruciate ligament (PCL), including both the anterolateral bundle (ALB) and posteromedial bundle (PMB), in cruciate-retaining total knee arthroplasty (CR-TKA) were simulated using a three-dimensional (3D) model of the tibial reconstruction. A total of 40 knees with medial osteoarthritis in patients scheduled for TKA were evaluated. Following surface registration of 3D computed tomography (CT) and 3D magnetic resonance imaging (MRI) models of the tibia with the PCL, the area of PCL attachment was calculated. Tibial bone cutting in the 3D CT model was simulated at 8 and 10 mm distal to the center of the lateral articular surfaces of the tibia and with posterior tibial slope angles of 0, 7, and 10 degrees. The percentages of the ALB and PMB tibial attachment areas that remained after cutting at 8 mm were, respectively, 21.8 ± 19.7% and 86.3 ± 17.7% with 0 degrees, 9.5 ± 10.4% and 64.1 ± 23.6% with 7 degrees, and 8.1 ± 6.7% and 51 ± 25.3% with 10 degrees. These results suggest that only half of the PCL attachment area was left after the bone cut simulation. Complete preservation of the ALB and PMB attachment areas requires appropriate selection of surgical procedures and devices.