COMPARISON BETWEEN IMAGE-FREE ROBOTIC ASSISTED AND CONVENTIONAL TOTAL KNEE ARTHROPLASTY: POSTOPERATIVE CT ASSESSMENT OF ALIGNMENT

Background: Navio Surgical System, a newer-generation robotic technology, is an image-free roboticassisted total knee arthroplasty (TKA) offering several advantages over older versions, including CT scan, the potential to dynamically assess soft tissue over a range of motion and the ability to use haptic control in bone preparation. Objective: The study aimed to compare the accuracy of component alignment between image-free robotic-assisted and conventional TKA. Methods: Forty patients were randomly assigned to two groups, 20 image-free robotic-assisted and 20 conventional TKA. The primary outcome was prosthetic alignment including mechanical axis alignment, epicondylar axis alignment and posterior tibial slope. The secondary outcomes included postoperative blood loss and operative time. Results: Significant difference were found in the postoperative mechanical axis between the image-free robotic group and the conventional group (1.15°±1° vs. 1.88°±1.19° deviated from neutral mechanical alignment, p = 0.043). There was significant difference in femoral rotational alignment between groups (1.00°±0.75° vs. 2.33°±0.96° deviated from the epicondylar axis, p<0.001). The mean posterior tibial slope did not significantly differ (3.89°±1.66° vs. 4.12°±1.37°, p=0.639). The operative time in the image-free robotic group was significantly longer than that of the conventional group (102.80 ± 11.18 min vs. 62.90 ± 3.28 min, p <0.001). Total blood loss in the image-free robotic group was significantly higher than conventional group (2.24±0.49 g/dl vs. 1.64±0.68 g/dl, p = 0.001). Conclusion: Image-free robotic-assisted TKA constituted a surgical procedure which could provide better accuracy in prosthetic alignment in both mechanical axis and rotational axis compared with conventional TKA. However, the image-free robotic assisted TKA involved higher blood loss and longer operative time.