Prospect of Robot Assisted Maxilla-Mandibula-Complex Reposition in Orthognathic Surgery

This paper investigates the feasibility and accuracy of robot assisted maxilla-mandibula-complex (MMC) reposition in orthognathic surgery. A robot system was established by an optical motion capture system and a universal robotic arm. Computer assisted surgical simulation (CASS), image guiding and robotic control software modules were developed according to the specific requirements for orthognathic surgery. The operation work flow includes data acquisition, virtual simulation, registration, osteotomy, robotic assisting bone segments reposition and fixation. The reposition and holding accuracy was tested on skull models. Optical scanner was used to acquire the intraoperative skull morphologies before and after the fixation. A postoperative CT scan was conducted when the fixation is completed. The virtual skull, intraoperative scan data and postoperative CT scan image were superimposed and compared. Error was defined as root mean square (RMS) of MMC on different images. The positioning accuracy was calculated by RMS between surface scan data before fixation and the virtual design skull. The holding accuracy was calculated by RMS between the surface scan before and after fixation. A validation test was conducted on five skull models. The mean accuracy of robotic assisting MMC reposition was 0.75 ±0.69 mm while the mean holding accuracy during the fixation procedure was 1.56±1.2mm. The accuracy of robot assisted MMC reposition was clinical feasible. The holding accuracy during fixation procedure is less satisfactory than that of repositioning. Further investigation is needed to improve the holding solidity of the robotic manipulator.