Frameless Patient Tracking With Adhesive Optical Skin Markers for Augmented Reality Surgical Navigation in Spine Surgery

Abstract

Study Design. Observational study. Objective. The aim of this study was to evaluate the accuracy of a new frameless reference marker system for patient tracking by analyzing the effect of vertebral position within the surgical field. Summary of Background Data. Most modern navigation systems for spine surgery rely on a dynamic reference frame attached to a vertebra for tracking the patient. This solution has the drawback of being bulky and obstructing the surgical field, while requiring that the dynamic reference frame is moved between vertebras to maintain accuracy. Methods. An augmented reality surgical navigation (ARSN) system with intraoperative cone beam computed tomography (CBCT) capability was installed in a hybrid operating room. The ARSN system used input from four video cameras for tracking adhesive skin markers placed around the surgical field. The frameless reference marker system was evaluated first in four human cadavers, and then in 20 patients undergoing navigated spine surgery. In each CBCT, the impact of vertebral position in the surgical field on technical accuracy was analyzed. The technical accuracy of the inserted pedicle devices was determined by measuring the distance between the planned position and the placed pedicle device, at the bone entry point. Results. The overall mean technical accuracy was 1.65 ± 1.24 mm at the bone entry point (n = 366). There was no statistically significant difference in technical accuracy between levels within CBCTs (P ≥ 0.12 for all comparisons). Linear regressions showed that null- to negligible parts of the effect on technical accuracy could be explained by the number of absolute levels away from the index vertebrae (r 2 ≤ 0.007 for all, β ≤ 0.071 for all). Conclusion. The frameless reference marker system based on adhesive skin markers is unobtrusive and affords the ARSN system a high accuracy throughout the navigated surgical field, independent of vertebral position. Level of Evidence: 3

Augmented reality navigation in spine surgery: a systematic review

“…When using manual registration and direct surface tracking, the AR image is manually adjusted to match the reality thereby inducing a potential registration error. Intraoperative imaging in combination with optical markers or a DRF, however, allows for an accurate automatic coregistration [7,10]. Nonetheless, an isolated comparison between Monitor-AR and HMD-AR on the one hand, and optical markers and surface tracking on the other hand, cannot be performed on the currently available data.…”

Multi-view 3D skin feature recognition and localization for patient tracking in spinal surgery applications

“…The accuracy, of roughly 0.6 mm at skin level, achieved with the current framework should be seen in light of previous results obtained by the ARSN system relying on adhesive skin markers. In a recent study using ARSN, Burström et al [32] demonstrated a technical accuracy of 0.94 ± 0.59 mm and 1.97 ± 1.33 mm, respectively, for cadaveric and clinical cases of pedicle screw placement. The difference in accuracy, could be attributed to the actual placement of pedicle screws in a clinical situation.…”

Frameless neuronavigation with computer vision and real-time tracking for bedside external ventricular drain placement: a cadaveric study

“…16 Other groups have advocated the use of fiducial CT markers to improve spatial and temporal registration efficiency. 26,27 However, this approach poses its own set of challenges, including the need to obtain additional CT scans of the patient specifically dedicated to the registration effort. Placement of deep brain stimulation electrodes is one such example in which this technology has an advantage over current frame-based or frameless methods, which require additional CT scans and fiducial markers.…”