A surgical telemanipulator for femur shaft fracture reduction

We present a surgical telemanipulator system supporting long bone fracture reduction procedures. This paper gives an overview of the robotic system developed by our working group and describes a possible workflow for telemanipulated fracture reduction. The concepts enabling an intuitive control of the robot using a joystick with force feedback as input device are also described.

With our robotic set-up we performed a test series, in order to evaluate the achievable reposition accuracies and operation times. 11 femoral shaft fractures in seven human donors have been reduced with the telemanipulator and the results have been compared with those achieved by conventional manual and navigated manual repositions.

All fractures in our test series could be reduced successfully with the telemanipulator, achieving a mean rotational deviation of 4.9 degrees in axial direction and 2.5 degrees and 3.5 degrees in AP and lateral direction. We could find no statistically significant difference between the accuracies achieved by the telemanipulator and those achieved by the two manual procedures. The image intensifier usage times of our telemanipulated repositions were conspicuously lower compared to the conventional manual repositions and statistically significant lower compared to the navigated repositions.

We could show that robot-assisted fracture reduction is possible, yielding good accuracies and a conspicuous reduction of X-ray irradiation. However, we also show the limitations regarding reposition accuracies of telemanipulated fracture reduction when it is based on 2D X-ray imaging only. From the combination of 3D imaging, automated computation of the reduction parameters, and automated force/torque guided reduction by the robot we expect to overcome these limitations in our future work.