Augmented reality in pelvic surgery: using an AR-headset as intraoperative radiation-free navigation tool

The incidence of acetabular and pelvic fractures is rising significantly. Pelvic ring fractures rank as the sixth most common fractures in adults, with the majority occurring in the elderly. Due to complications related to surgical approaches, with rates of up to 31%, there is an increasing demand for minimally invasive surgical techniques. Augmented Reality (AR) has the potential to facilitate spatial orientation by a sophisticated user interface. The aim of this study was to develop an AR-based, radiation-free navigation system for pelvic fractures.

The Microsoft® HoloLens 2 was used as the AR headset. The Unity® game engine was used for programming. Pelvic models from Sawbones® served as the model. Segmentation was performed using Slicer3D by Slicer Corporation. The symphysis and both anterior superior iliac spines were defined as anatomical reference points. Ten pelvic models were used for testing. A preoperatively defined drill trajectory was displayed to the surgeon. A total of 20 S1 screws and 19 S2 screws were placed using only AR navigation without visual access to the pelvic model. Screw placement was controlled using CT.

The matching process took an average of 3 min and 28 s. 18 out of 20 (90%) S1 screws and 3 out of 20 (15%) S2 screws were placed correctly. In most cases, no perforation occurred. The mean procedure time was 7 min for S1 screws and 5 min for S2 screws.

Proper drilling was achieved by displaying the trajectories via AR, particularly for S1 screws, where a slightly wider drilling corridor was aimed for compared to S2 screws. No registration scan was necessary with our matching method. No intraoperative radiation was required.