Abstract
The greatest feature of BCR-TKA is both the anterior cruciate ligament (ACL) and posterior cruciate ligament are retained while either the ACL or both the ligaments are transected in traditional TKA. However, a highly accurate component configuration is a necessity in order to maximize the remaining ligaments’ function. We performed a biomechanical investigation to evaluate the influence of component configuration on post-operative knee motion in BCR-TKA. Three fresh-frozen human cadaveric knees were evaluated using a 6 -degree-of-freedom robotic system. In accordance with the clinical procedure of measured resection technique, the size and shape of the femoral and tibial components were selected so that they matched with those of each knee (Standard) (Fig.1). Other sets of components curve also prepared by means of upsizing the posterior femoral condyle for 1 mm and 2 mm (US1 & US2), and downsizing it for 1 mm and 2 mm (DS1 & DS2), comparing to that of standard. For each TKA-treated knee, the anterior-posterior (AP) and varus-valgus (VV) laxities were measured. Results revealed that the AP laxities of all the TKA-treated groups were almost same as that of intact knee at full extension but they were much larger at all flexion angles. The AP laxity was significantly decreased with femoral condyle upsizing at 60 degree and 90 degree of flexion while it remained unchanged at full extension and 30 degree of flexion. Similar trends were observed in VV laxity except that the laxities of all the TKA-treated groups were larger at full extension and all flexion angles. It is suggested that the laxity of TKA-treated knee at flexion angles over 60 degree can be controlled by the configuration change of femoral posterior condyle.
