# Augmented Reality: Mapping Methods and Tools for Enhancing the Human Role in Healthcare HMI
## 3 Results
### Intraoperative Solution
#### 3.3.2 Spine Surgery
To verify its accuracy, the navigation system developed using AR technology was compared with the traditional FH method, and it was found that in a laboratory environment, the data provided by the AR headset and the overlaid operating plane increased the accuracy of pilot holes for SAI screws with regards to the conventional FH. The study of [PERSON] et al. [44] is the first reporting clinical case series that evaluated the accuracy of sixty-three percutaneous pedicle screws inserted using an AR-HMD system approved by the FDA. The system used a marker and CT images acquired during the operation for registration, and a marker for tracking. The pedicle screw placement procedure was performed in nine patients in both the lumbar and thoracic spine and achieved 100% accuracy regardless of the indications for the procedure. Comparable results were also obtained in other studies, in which other positioning systems (such as robotic systems) were used [25; 55]. The study by [PERSON] et al. [55] evaluated an AR-mediated percutaneous thoracic and lumbosacral pedicle screw placement system in a cadaveric study, with an HMD using wireless optical tracking cameras, directly embedded in the headset. This technique has reported insertion accuracy rates ranging from 83.9% to 100% and is associated with varying amounts of radiation exposure for the patient and the medical team, depending on the workflow and their experience. Despite improvements in accuracy, drawbacks have commonly been reported with manual computer navigation that can result in inefficiencies and procedural errors. Another AR system was used by [PERSON] et al. [25] for placing a percutaneous pedicle screw during lumbar transforminal interbody fusion. The result was 94% accuracy; however, this system does not involve AR HMD but visualizes the data on remote displays. Furthermore, a lack of device position tracking requires intraoperative fluoroscopy to inspect the insertion of the screw, especially in those patients who suffer from obesity. [PERSON] et al. [46] described and evaluated screw placement using SpineAR, a prototype commercial AR-HMD platform with real-time navigation guidance. SpineAR uses an AR HMD-based user interface to display real-time navigation images from intraoperative 3D imaging. In this work, the accuracy of screw placement was evaluated in a laboratory setting where pedicle screws were placed into commercial 3D-printed models of the lumbar spine by surgeons and trainees with distinct levels of experience. Accuracy was evaluated and compared with data reported in the literature on the FH screw placement technique, reporting comparable accuracy rates. In a cadaver study, [PERSON] et al. [56] evaluated the accuracy of surgical navigation for pedicle screw insertion with an AR head-mounted device. The comparison was performed with a state-of-the-art pose-tracking system for navigation. Three-dimensional fluoroscopy was used as an intraoperative registration approach in both cases in order to maintain the same experimental settings and comparable outcomes. In addition, for the AR group, the positions of the markers were plotted in real-time by considering instrumentation movement, and preoperative 3D planning was superimposed on the actual anatomy with a hologram. Holographic navigation using an HMD resulted to achieve outcomes comparable with the state-of-the-art. [PERSON] et al. [67] assessed, in experimental bone environments, the feasibility and accuracy of percutaneous lumbar pedicle screw placement using an AR-guided method from CT images compared to placement with a radio-guided method. In this study, an automatic method for aligning an AR hologram was also compared with a manual one. Each of the twelve lumbar spine sawbones was fully embedded in hardened opaque agar and equipped with a cubic marker. An intraoperative CT scan was acquired for each phantom and the generated virtual 3D model was uploaded on Microsoft HoloLens.