Accuracy of intraoperative bone registration and stereotactic boundary reconstruction during total knee arthroplasty surgery

Abstract

Background:The intraoperative registration of the bones play a crucial role in image-based computer-assisted knee arthroplasty to achieve accurate implant placement and to create reliable stereotactic bone boundaries for robot-assisted surgical systems. Method:This study assessed the intraoperative registration accuracy on six intact fresh frozen cadavers.Results: Rotational errors around the mechanical axis were the largest, with a standard deviation of 1.2°and outliers up to 3.7°. The mean translational errors were lower than 1 mm, with outliers up to 1.5 mm. These errors were amplified to 2 mm for the registration-based reconstruction of the posterior bone surface at the resection levels. Conclusion:Given the cumulative behaviour of surgical errors, registration errors can affect the final implant positioning. Furthermore, inaccuracies in the reconstructed bone boundary directly affect the virtual stereotactic boundaries used in robotic-assisted surgery and can result in an incomplete resection or inadvertent soft tissue damage. K E Y W O R D Sanatomy, technology | INTRODUCTIONTotal knee arthroplasty (TKA) is a common and cost-effective surgical treatment for osteoarthritis of the knee joint. 1 However, 10%-20% of patients remain dissatisfied after TKA. 2 Malpositioning of the implant is associated with implant failure, and as a result, patient dissatisfaction. 3,4 To improve the accuracy of the implant position according to a preoperative plan, navigation and robotics have been introduced. 5 These technologies have proven to be successful in reducing the frequency of outliers of more than 3°, but errors up to these values still occur. [6][7][8][9][10] Navigation and robotic systems are in most cases using an optical tracking system (OTS) and a tracked pointer to determine the position and orientation of the femur and tibia with respect to the attached dynamic reference bases (DRB). 9,11,12 This intraoperative bone registration process is subject to a margin of error which affects the surgical accuracy. [11][12][13][14][15] The total operative accuracy is determined by a succession of inaccuracies in the following surgical steps: bone registration and matching of the surgical plan, tracking of the bones and the surgical objects in space, bone preparation and implant placement. During bone registration, the software model is matched with the patient's specific anatomy. As

Accuracy of on-site teleoperated milling with haptic assistance

“…For image-based navigation, modern algorithms achieve average surface distances of up to 0.31 mm for segmentation of bone from computer tomography images [ 15 ]. For manual bone registration with anatomical landmarks registration errors of 1 mm and 1.2° can occur [ 16 ]. On the slave side, the accuracy of the robot also depends on the tracking accuracy and the rigidity of the burr and the burr mount.…”