Figure 1: Two types of prosthesis used for posterior cruciate ligament–retaining (CR-type) TKA in this study; (a) Anterior view of the Flexible Nichidai Knee (FNK) CR-type component, (b) Anteroposterior (AP) and lateral radiographs of the FNK CR-type component, (c) Anterior view of the Foundation Total Knee System CR-type component, (d) AP and lateral radiographs of the Foundation Total Knee System CR-type component.