P120. Augmented reality navigation for percutaneous thoracolumbar pedicle screws: a prospective clinical study

BACKGROUND CONTEXT

Conventional navigation systems depend on a separate imaging system and use of passive infra-red cameras with a bulky dynamic reference frame (DRF) attached to the spine and to the instruments for live tracking. This often leads to 1) issues with line of sight 2) need for an invasive procedure to attach the DRF 3) lowered accuracy due to inadvertent bumping of the DRF and when point of interest is further from the location of the DRF and 4) a need for repeated re-registrations that can affect the surgical workflow and impact the procedure time. These common issues that impede the adoption of navigation can be bypassed using an Augmented Reality Surgical Navigation system (ARSN), that combines the use of superior quality 3D intra-operative imaging and optical camera based Augmented Reality Navigation (ARN), noninvasive dynamic patient monitoring and on-shaft optical trackers on the Jamshidi needles to provide real time visual feedback of instrument location, without relying on fluoroscopy.

PURPOSE

To determine the accuracy of percutaneous pedicle screw placement when using ARSN.

STUDY DESIGN/SETTING

A single-arm, prospective multicenter clinical study.

PATIENT SAMPLE

A total of 211 pedicle screws were placed percutaneously in 39 patients between levels T2 and S1. The predominant indication was trauma (42%). However, patients with instability of the spine due to degenerative and neoplastic diseases were also included.

OUTCOME MEASURES

Accuracy of pedicle screw placement according to Gertzbein grading (Grade 0: no breach; Grade 1: 4mm breach) determined by three independent reviewers. The median time required to insert the pedicle screw in the right location when using the system was also noted.

METHODS

Navigation was performed in a hybrid OR including surgical table, motorized flat detector C-arm with intraoperative 2D/3D imaging capabilities, optical video cameras integrated in the detector for ARN, and patient motion tracking using skin markers. The C-arm rotated 180 degrees in 10 seconds during acquisition, creating a 3D Cone-Beam CT (CBCT) of the area of interest of 4-8 levels. A disposable Jamshidi needle with optical markers etched on the shaft was used to guide the needle to the desired location in the vertebral body using ARN.

RESULTS

Overall accuracy (Gertzbein 0-1) was 98.1% (95% CI 95.2-99.5). For thoracic screws (n=69), accuracy was 95.7%, for lumbar screws (n=126) 99.2%. Grade 0 screws (no breach) were 93% overall (86% in thoracic and 96% in lumbar levels). Four screws were graded as 2 (2-4 mm breach), with a medial positioning. Three of them were in the upper thoracic spine. None was associated with a neurological consequence. No screw was highly misplaced (> 4mm error). Six screws (2.7%) were intraoperatively revised. Median time per screw was 6 minutes and 25 sec (± 3.3 min).

CONCLUSIONS

Use of ARN leads to a high rate of accurate pedicle screw placement. The use of ARSN favorably compares to screw placement times reported in literature.

FDA DEVICE/DRUG STATUS

ClarifEye surgical navigation system (Philips Healthcare) (Approved for this indication)