Kantonsspital St.Gallen

Augmented Reality Navigated Sacral-Alar-Iliac Screw Insertion

Cyrill Dennler, Nico Akhavan Safa, David Ephraim Bauer, Florian Wanivenhaus, Florentin Liebmann, Tobias Götschi & Mazda Farshad


Sacral-alar-iliac (SAI) screws are increasingly used for lumbo-pelvic fixation procedures. Insertion of SAI screws is technically challenging, and surgeons often rely on costly and time-consuming navigation systems. We investigated the accuracy and precision of an augmented reality (AR)-based and commercially available head-mounted device requiring minimal infrastructure.

A pelvic sawbone model served to drill pilot holes of 80 SAI screw trajectories by 2 surgeons, randomly either freehand (FH) without any kind of navigation or with AR navigation. The number of primary pilot hole perforations, simulated screw perforation, minimal axis/outer cortical wall distance, true sagittal cranio-caudal inclination angle (tSCCIA), true axial medio-lateral angle, and maximal screw length (MSL) were measured and compared to predefined optimal values.

In total, 1/40 (2.5%) of AR-navigated screw hole trajectories showed a perforation before passing the inferior gluteal line compared to 24/40 (60%) of FH screw hole trajectories ( < .05). The differences between FH- and AR-guided holes compared to optimal values were significant for tSCCIA with -10.8° ± 11.77° and MSL -65.29 ± 15 mm vs 55.04 ± 6.76 mm ( = .001).

In this study, the additional anatomical information provided by the AR headset and the superimposed operative plan improved the precision of drilling pilot holes for SAI screws in a laboratory setting compared to the conventional FH technique. Further technical development and validation studies are currently being performed to investigate potential clinical benefits of the AR-based navigation approach described here.

citation Dennler C, Safa N A, Bauer D E, Wanivenhaus F, Liebmann F, Götschi T, Farshad M. Augmented Reality Navigated Sacral-Alar-Iliac Screw Insertion. Int J Spine Surg 2021; 15:161-168.
type journal paper/review (English)
date of publishing 18-02-2021
journal title Int J Spine Surg (15/1)
ISSN print 2211-4599
pages 161-168
PubMed 33900970
DOI 10.14444/8021