284 CT-Based Assessment of Prone Versus Lateral Pedicle Screw Placement Accuracy: A Retrospective Single-surgeon Study

Abstract

INTRODUCTION: Lateral lumbar interbody fusion (LLIF) including the anterior-to-psoas oblique lumbar interbody fusion (OLIF) has conventionally relied on pedicle screw placement (PSP) for construct stabilization. Single-position surgery with lumbar interbody fusion (LIF) in the lateral decubitus position with concomitant PSP has been associated with increased operative efficiency. What remains unclear is the accuracy of PSP with robotic guidance when compared to the more familiar prone patient positioning. METHODS: We identified all consecutive patients treated with interbody fusion and PSP in the prone or lateral position by a single surgeon between January 2019 and October 2022. All pedicle screws placed were analyzed using CT imaging to determine appropriate positioning according to the Gertzbein-Robbins Classification Grading System. Multivariate logistic regression models were constructed to identify risk factors for the occurrence of a radiographically significant breach. RESULTS: 89 consecutive patients were included (n = 690 screws), of whom 46 were treated in the prone position (n = 477 screws) and 43 in the lateral decubitus position (n = 213 screws). There were fewer breaches in the prone (n = 13; 2.7%) versus lateral decubitus group (n = 15; 7.0%; p = 0.012). Nine (1.9%) radiographically significant breaches occurred in the prone group compared to 10 (4.7%) in the lateral decubitus group (p = 0.019), for a prone vs. lateral decubitus pedicle screw accuracy rate of 98.1% vs. 95.3%. There were no significant differences in BMI between prone vs. lateral decubitus cohorts (30.1 vs. 29.6) or breached patients vs. non-breached patients (31.2 vs. 29.5). In multivariate models, prone position was the only significant protective factor for screw accuracy; we did not identify any other significant risk factors for screw breach. CONCLUSIONS: The present data suggest pedicle screws placed with robotic assistance have higher placement accuracy in the prone position.