A Quantitative Assessment of the Accuracy and Reliability of Robotic Guidance for Lumbar Fusion: A Technique and Application Accuracy

Presented at SMISS Annual Forum 2018
By Cory Hartman MD, MBA
With

Disclosures: Cory Hartman MD, MBA None

Introduction:

Minimally-invasive (MIS) approaches to the anterior column such as lateral (LIF) or transforaminal lumbar interbody fusion (TLIF) require percutaneous screw fixation to achieve circumferential instrumentation. Robotic guidance represents a new technology for augmenting the surgical workflow to improve screw placement accuracy and decreasing the ionizing radiation exposure to the surgical team.

Aims/Objectives:

Here we report our initial surgical experience with robotically assisted percutaneous screw placement following LIF and review our surgical workflow.

Methods:

Consecutive patients undergoing single level fusion with robotically assisted percutaneous pedicle screw fixation (PSF) in prone or lateral decubitus position were identified. A novel CT-guided robotic guidance arm was used for screw placement (ExcelsiusGPS) in combination with the O-Arm (Medtronic). Demographic data, surgical timing, and perioperative complications were collected. Postoperative thin cut CT scans were used for screw localization. X, Y, Z coordinates of the screw tip and tail were calculated and compared with the intended target trajectory to assess targeting error. A breach was defined as violation of lateral or medial pedicle wall.

Results:

Twenty-seven patients with lumbar pathology underwent robotic minimally invasive lumbar interbody fusion with 112 robotically assisted percutaneous pedicle screws. The breach rate was 2.7%. Across 17 patients, the mean 3D accuracy was 4.8±2.3mm, mean 2D accuracy was 2.6±1.2mm, and mean angular offset was 5.5±4.1°. 3D accuracy was correlated with age (R=0.25, p=0.037) and BMI (R=0.252, p=0.038); accuracy did not differ between vertebral body levels (p>0.22). Mean operative time for percutaneous screws was 183±54 minutes and did not improve significantly over time.

Conclusions:

Robotic guidance system provides for accurate percutaneous pedicle screw placement in the majority of cases. Nonetheless, the technology still represents an early phase of development, with a steep learning curve that trends towards improved surgical times with subsequent use. Future studies are needed to demonstrate the utility of this novel guidance system and continued improvement in workflow.