Ultrasound Image Guided and Mixed Reality-Based Surgical System With Real-Time Soft Tissue Deformation Computing for Robotic Cervical Pedicle Screw Placement.

OBJECTIVE: Cervical pedicle screw (CPS) placement surgery remains technically demanding due to the complicated anatomy with neurovascular structures. State-of-the-art surgical navigation or robotic systems still suffer from the problem of hand-eye coordination and soft tissue deformation. In this study, we aim at tracking the intraoperative soft tissue deformation and constructing a virtual-physical fusion surgical scene, and integrating them into the robotic system for CPS placement surgery. METHODS: Firstly, we propose a real-time deformation computation method based on the prior shape model and intraoperative partial information acquired from ultrasound images. According to the generated posterior shape, the structure representation of deformed target tissue gets updated continuously. Secondly, a hand tremble compensation method is proposed to improve the accuracy and robustness of the virtual-physical calibration procedure, and a mixed reality based surgical scene is further constructed for CPS placement surgery. Thirdly, we integrate the soft tissue deformation method and virtual-physical fusion method into our previously proposed surgical robotic system, and the surgical workflow for CPS placement surgery is introduced. RESULTS: We conducted phantom and animal experiments to evaluate the feasibility and accuracy of the proposed system. Our system yielded a mean surface distance error of 1.52 ± 0.43 mm for soft tissue deformation computing, and an average distance deviation of 1.04 ± 0.27 mm for CPS placement. CONCLUSION: Results demonstrate that our system involves tremendous clinical application potential. SIGNIFICANCE: Our proposed system promotes the efficiency and safety of the CPS placement surgery.

Augmented reality based navigation for distal interlocking of intramedullary nails utilizing Microsoft HoloLens 2.

BACKGROUND AND OBJECTIVE: The distal interlocking of intramedullary nail remains a technically demanding procedure. Existing augmented reality based solutions still suffer from hand-eye coordination problem, prolonged operation time, and inadequate resolution. In this study, an augmented reality based navigation system for distal interlocking of intramedullary nail is developed using Microsoft HoloLens 2, the state-of-the-art optical see-through head-mounted display. METHODS: A customized registration cube is designed to assist surgeons with better depth perception when performing registration procedures. During drilling, surgeons can obtain accurate and in-situ visualization of intramedullary nail and drilling path, and dynamic navigation is enabled. An intraoperative warning system is proposed to provide intuitive feedback of real-time deviations and electromagnetic disturbances. RESULTS: The preclinical phantom experiment showed that the reprojection errors along the X, Y, and Z axes were 1.55 ± 0.27 mm, 1.71 ± 0.40 mm, and 2.84 ± 0.78 mm, respectively. The end-to-end evaluation method indicated the distance error was 1.61 ± 0.44 mm, and the 3D angle error was 1.46 ± 0.46°. A cadaver experiment was also conducted to evaluate the feasibility of the system. CONCLUSION: Our system has potential advantages over the 2D-screen based navigation system and the pointing device based navigation system in terms of accuracy and time consumption, and has tremendous application prospects.

A review on the applications of virtual reality, augmented reality and mixed reality in surgical simulation: an extension to different kinds of surgery.

Background: Research proves that the apprenticeship model, which is the gold standard for training surgical residents, is obsolete. For that reason, there is a continuing effort toward the development of high-fidelity surgical simulators to replace the apprenticeship model. Applying Virtual Reality Augmented Reality (AR) and Mixed Reality (MR) in surgical simulators increases the fidelity, level of immersion and overall experience of these simulators.Areas covered: The objective of this review is to provide a comprehensive overview of the application of VR, AR and MR for distinct surgical disciplines, including maxillofacial surgery and neurosurgery. The current developments in these areas, as well as potential future directions, are discussed.Expert opinion: The key components for incorporating VR into surgical simulators are visual and haptic rendering. These components ensure that the user is completely immersed in the virtual environment and can interact in the same way as in the physical world. The key components for the application of AR and MR into surgical simulators include the tracking system as well as the visual rendering. The advantages of these surgical simulators are the ability to perform user evaluations and increase the training frequency of surgical residents.