A fluoroscopic-based navigation system for ACL reconstruction assisted by robot

Entry position of the graft is very important in anterior cruciate ligament (ACL) reconstruction. However the determination of entry position is very difficult to the surgeon. In this paper, a navigation and evaluation system assisted by the 6-DOFS robot is implemented for the simulation evaluation and planning insertion points based on quadrant method for the femur and Stäublis method for the tibia on the lateral X-ray image of knee joint. Meanwhile, the implementation of the key technologies such as image correction, image registration, C-arm calibration, video tracking, bone surface reconstruction, image fusion, 6-DOFS robot, and virtual simulation are introduced. Finally, Experiments about the tunnel planning method and real time tracking of surgical apparatus are implemented on 8 bone of plastic models (Sawbone, Swiss) and 10 bones of the goat. In the experiment, the tibia rotates around the femur under the surgeon's implementation to evaluate the planning result with the virtual simulation and evaluation module. The positioning error is 1.59mm from analysis on 30 space targets. The virtual reconstruction ACL is satisfied with two important criteria of the best isometry and collision detection between graft and intercondylar surface of femur. The results are well accepted in operations. In order to satisfying with the request of exact operation in ACL reconstruction, we have developed 6-DOFS passive robot to assist the surgeons entry positioning and drilling of implant tunnels, implementing exact operation in knee joint.