Kinematic comparison of posterior cruciate sacrifice versus substitution in a mobile bearing total knee arthroplasty

Interest in mobile bearing total knee arthroplasty (TKA) has increased significantly. The objective of this in vivo Study was to analyze 2 different mobile bearing TKAs during gait and during a knee bend from 0degrees to 90degrees flexion. Femorotibial contact positions for 10 subjects, implanted by a single surgeon, were analyzed using videofluoroscopy. Five subjects were implanted with a posterior-stabilized mobile bearing TKA (PS), and 5 subjects were implanted with a posterior cruciate-sacrificing mobile bearing TKA (PCs). Each subject, while under fluoroscopic surveillance, performed 2 weight-bearing activities: i) normal gait and ii) deep-knee bend. This study showed that the kinematic patterns for Subjects having either a PS or PCs mobile bearing TKA were similar during gait but different during a deep-knee bend. Subjects having a PS TKA experienced more posterior femoral rollback of the lateral condyle during the deep-knee bend. Findings of kinematic similarities in gait and differences in a deep-knee bend between these 2 mobile bearing designs arc similar to previously Published findings of fixed bearing posterior cruciate-retaining and PS TKA.