Augmented Reality-Assisted Femoral Bone Resection in Total Knee Arthroplasty

Background: An augmented reality (AR)-based navigation system allows visualization of the center of the femoral head and femoral mechanical axis superimposed on the surgical field during total knee arthroplasty (TKA) and may help surgeons to improve the accuracy of distal femoral resection.Methods: First, we resected 10 femoral Sawbones specimens using the AR-based navigation system and performed computed tomography (CT) to measure the resection angle of the distal part of the femur. We calculated the absolute values of the differences between angles measured using CT images and angles displayed on the smartphone screen of the navigation system. Second, we measured coronal alignment using standing long-leg radiographs for 72 patients undergoing TKA and compared the error in the resection angle between TKA using the AR-based navigation system and that using a conventional intramedullary guide.Results: In the experimental study, the absolute values of the differences between angles measured on CT images and angles displayed using the AR-based navigation system were 0.8 degrees +/- 0.5 degrees (range, 0.3 degrees to 1.9 degrees) in the coronal plane and 0.6 degrees +/- 0.5 degrees (range, 0.0 degrees to 1.4 degrees) in the sagittal plane. In the clinical study, the mean absolute value of the error in coronal alignment was significantly smaller in the AR-based navigation group than the intramedullary-guide group (1.1 degrees +/- 1.0 degrees [range, 0.0 degrees to 3.2 degrees] compared with 2.2 degrees +/- 1.6 degrees [range, 0.0 degrees to 5.5 degrees], respectively; 95% confidence interval, 0.5 degrees to 1.8 degrees; p < 0.001).Conclusions: The AR-based navigation system may enable surgeons to perform distal femoral resection more accurately than with the conventional intramedullary guide during TKA.