There is no criteria to select cruciate retaining (CR) or posterior substitute (PS) component in total knee arthroplasty (TKA). In this study, extension and flexion gaps were measured intra-operatively with posterior cruciate ligament (PCL) remained to reveal characteristics of the gaps. Component type selection, CR or PS, was decided intra-operatively according to the gaps in each knee. One hundred and sixty knees with osteoarthritis were investigated. Extension gap (EG) was made by resection of 8 mm distal femur and 10 mm proximal tibia. After measurement of femoral AP size, about 4 mm bigger 4-in-1 femoral cutting guide than measured size was used for pre-cut of femoral posterior condyle[Figure 1]. With this technique, flexion gap (FG) was made 4 mm smaller than usual measured resection. The gaps were measured by a tension device with 30 pounds tension and FG was corrected by the amount of pre-cut. According to the EG and corrected FG, component type was decided. Too small FG usually needed PCL resection or (and) smaller size of femoral component to make enough final FG. On the other hand, large FG needed careful consideration to sacrifice PCL for adequate final FG. In these cases, CR component was selected usually. If necessary, soft tissue was released for good ligament balance. As the final step of the surgical procedure, the size of femoral component was decided for adequate final FG. It was changeable up to 4 mm larger than measured size[Figure 2].Introduction
Materials and methods
