Navigated total knee arthroplasty: is it error-free?

Purpose The aim of this study was to determine whether errors do occur in navigated total knee arthroplasty (TKAs) and to study whether errors in bone resection or implantation contribute to these errors. Methods A series of 20 TKAs was studied using computer navigation. The coronal and sagittal alignments of the femoral and tibial cutting guides, the coronal and sagittal alignments of the final tibial implant and the coronal alignment of the final femoral implant were compared with that of the respective bone resections. To determine the post-implantation mechanical alignment of the limb, the coronal alignment of the femoral and tibial implants was combined. Results The median deviation between the femoral cutting guide and bone resection was 0 degrees (range -0.5 degrees to +0.5 degrees) in the coronal plane and 1.0 degrees (range -2.0 degrees to +1.0 degrees) in the sagittal plane. The median deviation between the tibial cutting guide and bone resection was 0.5 degrees (range -1.0 degrees to +1.5 degrees) in the coronal plane and 1.0 degrees (range -1.0 degrees to +3.5 degrees) in the sagittal plane. The median deviation between the femoral bone resection and the final implant was 0.25 degrees (range -2.0 degrees to 3.0 degrees) in the coronal plane. The median deviation between the tibial bone resection and the final implant was 0.75 degrees (range -3.0 degrees to +1.5 degrees) in the coronal plane and 1.75 degrees (range -4.0 degrees to +2.0 degrees) in the sagittal plane. The median post-implantation mechanical alignment of the limb was 0.25 degrees (range -3.0 degrees to +2.0 degrees). Conclusions When navigation is used only to guide the positioning of the cutting jig, errors may arise in the manual, non-navigated steps of the procedure. Our study showed increased cutting errors in the sagittal plane for both the femur and the tibia, and following implantation, the greatest error was seen in the sagittal alignment of the tibial component. Computer navigation should be used not only to guide the positioning of the cutting jig, but also to check the bone resection and implant position during TKA. Level of evidence IV.