Manual vs. robotic milling parameters for development of a new robotic system in cranial surgery

Advances in Robot-Assisted Surgery for Facial Bone Contouring Surgery

Since our team reported the application of robot-assisted surgery in facial contouring surgery in 2020, further clinical trials with large samples have been conducted. This paper will report the interim results of a single-center, large-sample randomized controlled trial of the first robot developed by our team for facial contouring surgery. Meanwhile, this research field will be systematically reviewed and prospected.

An experimental evaluation of the force requirements for robotic mastoidectomy

HYPOTHESIS

During robotic milling of the temporal bone, forces on the cutting burr may be lowered by choice of cutting parameters.

BACKGROUND

Robotic bone removal systems are used in orthopedic procedures, but they are currently not accurate enough for safe use in otologic surgery. We propose the use of a bone-attached milling robot to achieve the required accuracy and speed. To design such a robot and plan its milling trajectories, it is necessary to predict the forces that the robot must exert and withstand under likely cutting conditions.

MATERIALS AND METHODS

We measured forces during bone removal for several surgical burr types, drill angles, depths of cut, cutting velocities, and bone types (cortical/surface bone and mastoid) on human temporal bone specimens.

RESULTS

Lower forces were observed for 5-mm diameter burrs compared with 3-mm burrs for a given bone removal rate. Higher linear cutting velocities and greater cutting depths independently resulted in higher forces. For combinations of velocities and depths that resulted in the same overall bone removal rate, lower forces were observed in parameter sets that combined higher cutting velocities and shallower depths. Lower mean forces and higher variability were observed in the mastoid compared with cortical/surface bone.

CONCLUSION

Forces during robotic milling of the temporal bone can be predicted from the parameter sets tested in this study. This information can be used to guide the design of a sufficiently rigid and powerful bone-attached milling robot and to plan efficient milling trajectories. To reduce the time of the surgical intervention without creating very large forces, high linear cutting velocities may be combined with shallow depths of cut. Faster and deeper cuts may be used in mastoid bone compared with the cortical bone for a chosen force threshold.

Robotic mastoidectomy

HYPOTHESIS

Using image-guided surgical techniques, we propose that an industrial robot can be programmed to safely, effectively, and efficiently perform a mastoidectomy.

BACKGROUND

Whereas robotics is a mature field in many surgical applications, robots have yet to be clinically used in otologic surgery despite significant advantages including reliability and precision.

METHODS

We designed a robotic system that incorporates custom software with an industrial robot to manipulate a surgical drill through a complex milling profile. The software controls the movements of the robot based on real-time feedback from a commercially available optical tracking system. The desired path of the drill to remove the desired volume of mastoid bone was planned using computed tomographic scans of cadaveric specimens and then implemented using the robotic system. Bone-implanted fiducial markers were used to provide accurate registration between computed tomographic and physical space.

RESULTS

A mastoid cavity was milled on 3 cadaveric specimens with a 5-mm fluted ball bit. Postmilling computed tomographic scans showed that, for the 3 specimens, 97.70%, 99.99%, and 96.05% of the target region was ablated without violation of any critical feature.

CONCLUSION

To the best of our knowledge, this is the first time that a robot has been used to perform a mastoidectomy. Although significant hurdles remain to translate this technology to clinical use, we have shown that it is feasible. The prospect of reducing surgical time and enhancing patient safety by replacing human hand-eye coordination with machine precision motivates future work toward translating this technique to clinical use.

Force-based control of a compact spinal milling robot

BACKGROUND

Spine-milling operation during laminectomy surgery requires steady manipulation and intraoperative monitoring. A spinal milling robot with force-based control is introduced to improve the operation safety.

METHOD

The robot is designed with compact structure and simple configuration. Real-time thrust force is measured and three stages corresponding to the anatomical structures of the vertebra are identified, based on the analysis of typical characteristic parameters of the force profiles. The cross-correlation to the standard profiles are adopted to judge the milling status. A 1 mm margin is prescribed to stop the procedure before the lamina is thoroughly milled through.

RESULTS

Automatic robot-milling experiments on porcine vertebrae are conducted, based on the force-based control method, and the procedure is stopped when the critical condition is met. The average thickness of the milled part is 1.1 mm, and no penetration occurs.

CONCLUSION

The spinal milling robot could provide steady manipulation, facilitate the surgeon's labour with an automatic feeding process and improve the safety of the operation with enhanced monitoring.