Comparison of the radiological results between fluoroscopy-assisted and navigation-guided total knee arthroplasty

The efficacy and accuracy of computer navigation have been proved during recent years. But most of recent studies focused on the coronal alignment in total knee arthroplasty and less on sagittal alignment. We retrospectively compared the results of the radiographs of 35 primary TKAs using a non-image based navigation system and 36 primary TKAs using fluoroscopy-assisted conventional technique. To compare the radiographic results, the following parameters were measured: mean mechanical femorotibial angle, mean femorotibial anatomical angle, mean coronal femoral component angle, mean coronal tibial component angle, mean sagittal femoral component angle, and mean sagittal tibial component angle. The navigation TKA showed better accuracy and consistency in mechanical axis deviation, coronal femoral component angle, and sagittal tibial component angle. The coronal tibial component position was acceptable in both groups. The navigation TKA markedly improved the restoration of mechanical axis, but not so much in sagittal femoral component position. The fluoroscopy-assisted conventional TKA had a tendency that femoral component was inserted in flexed position than in navigation TKA. Unlike the fluoroscopy-assisted conventional TKA, the femoral component was inserted in slightly extended position in the navigation TKA than expected. In conclusion, even though the use of navigation in TKAs help the surgeon to achieve good results, the surgeon should know the tendency of extension of the femoral component in sagittal plane to avoid anterior notching.