A Surgical Robotic System for Long-Bone Fracture Alignment: Prototyping and Cadaver Study

In this paper, we design, develop, and validate a surgical robotic system, entitled Robossis, to assist long-bone fracture reduction, i.e., alignment, surgeries. Unlike traditional long-bone fracture surgeries, Robossis enables the surgeon to precisely align the fractured bone in the presence of large traction forces and torques. The proposed surgical system includes a novel 3-armed robot, a bone-gripping mechanism, and a master controller. The 6-DOF 3-armed wide-open parallel robot has a unique architecture, which facilitates positioning the bone inside the robot, providing a large workspace for surgical maneuvers. Kinematic analysis shows that the symmetric 3-armed mechanism provides a significant advantage over the Gough-Stewart platform, i.e., 15 times larger rotational workspace, which is a vital advantage for fracture alignment. Theoretical and experimental testing are performed to demonstrate Robossis performance, including high accuracy and force insertion capabilities. A successful cadaver test was performed using a Robossis prototype, which shows that guided by intraoperative X-ray imaging, Robossis is able to manipulate bone in all translational and rotational directions while encountering the muscle payload surrounding the femur. Robossis is designed to balance accuracy, payload, and workspace, and its innovative design presents major advantages over the existing robot designs for the reduction of long-bone fractures.