1136 What is the Marginal Cost of Using Robot-Assistance or Navigation for Transforaminal Lumbar Interbody Fusion? A Time-Driven Activity-Based Cost Analysis

INTRODUCTION: Neurosurgeons are often unaware of the true costs of spine procedures. METHODS: Total cost was divided into direct and indirect costs. We identified all instances of RA-TLIF (n=20), ION-TLIF (n=59), and freehand TLIF (n=233) from 2020 to 2022 at our institution. Software was developed to automate the extraction of all intraoperatively utilized personnel and material resources from the electronic medical record (EMR). Total costs were determined through a combination of direct observation, EMR extraction, and inter-departmental collaboration (business operations, sterile processing, pharmacy, and plant operation departments). Multivariable linear regression analysis was performed to compare costs between TLIF modalities, accounting for patient-specific factors as well as number of levels fused, surgeon, and hospital site. RESULTS: The average total intraoperative cost per case for the RA-, ION- and freehand TLIF cohorts was $24,838 +/- $10,748, $15,991 +/- $6,254 and $14,498 +/- $6,580, respectively. Regression analysis revealed that RA-TLIF had significantly higher intraoperative cost compared to both ION-TLIF (β-coefficient: $7,383 +/- $1,575, p<0.001) and freehand TLIF (β-coefficient: $8,182 27 +/- $1,523, p<0.001). These cost differences were primarily driven by supply cost. However, there were no significant differences in intraoperative cost between ION-TLIF and freehand TLIF (p=0.32). CONCLUSIONS: We demonstrate a novel use of TDABC methodology to compare different modalities for executing the same type of lumbar fusion procedure. RA-TLIF entails significantly higher supply cost when compared to other modalities, which explains its association with higher total intraoperative cost. The use of ION, however, does not add extra expense compared to freehand TLIF when accounting for confounders.