Frontal alignment in total knee arthroplasty. Comparative study between radiographic measurement and surgical navigation

Abstract

ObjectiveTo establish the concordance between angulation of the femoro-tibial mechanical axis measured with X-rays and surgical navigation in both the pre and postoperative period after a total knee arthroplasty (TKA) was implanted. Material and methodPre and postoperative measurements were analysed in 88 TKA of the same model and all performed with the same surgical navigation system. The mechanical frontal angle (MFA) and femoro-tibial anatomic angle were measured before and after the TKA. The angulation was digitally measured with a teleradiography. In the navigation, the femoro-tibial angle at rest, forced varus and valgus were registered and the average of these three measurements was calculated. ResultsThe mean preoperative MFA measured on the radiograph was 4.55°. The mean of the same angle measured on the postoperative radiograph was 1.72°, (p=0.05). The mean of the MFA measured with navigation before TKA was 3.12° and after the implant with navigation was 0.53 (p=0.013). The concordance coefficient between the MFA in teleradiography and in navigation was 0.869 (p<0.001) preoperatively and 0.709 postoperatively (p=0.017). ConclusionsWe found a strong concordance between radiographic and surgical navigation measurements of the MFA. This may imply that teleradiography is not necessary when using surgical navigation in TKA.