How do robot assistance and image-guided navigation impact drivers of intraoperative cost for transforaminal lumbar interbody and fusion? A time-driven activity-based cost analysis

Introduction: Image-guidance navigated (IGN) and robot-assisted (RA) spine surgery have been two of the most influential innovations in spine surgery in recent decades. Here, we use time-driven activity-based costing (TDABC) methodology to determine how choice of instrumentation guidance influences intraoperative costs for transforaminal lumbar interbody and fusion (TLIF). Specifically, we compared costs between robot-assisted RA-TLIF, IGN-TLIF, and freehand (non-navigated, non-robotic) TLIF.

Methods: We identified all instances of RA-TLIF, IGN-TLIF, and freehand TLIF from 2020 to 2022 at our institutional enterprise. Individual costs were obtained by direct observation, electronic medical records, and through querying multiple departments (business operations, sterile processing, plant operations, and pharmacy). Timestamps for all involved personnel and material resources were documented. We performed multivariable linear regression analyses comparing costs between these modalities when accounting for patient-specific factors as well as surgeon, hospital site and duration of surgery.

Results: The average total intraoperative cost per case for RA, IGN and freehand TLIF cohorts was $24,838 +/- $10,748, $17,533 +/- $9,312 and $14,149 +/- $5,657, respectively. Regression analysis revealed that RA-TLIF had significantly higher intraoperative costs compared to both IGN-TLIF (β-coefficient: $5,364 +/- $1,351, p< 0.001) and freehand TLIF (β-coefficient: $6,815 +/- $1,314, p< 0.001) modalities. These cost differences were primarily driven by supply costs. However, there were no significant differences in intraoperative costs between IGN-TLIF and freehand TLIF (p=0.085).

Conclusion : We demonstrate a novel use of TDABC methodology to pinpoint the exact drivers of cost variability between different treatment modalities for the same procedure. RA-TLIF entails significantly increased supply costs when compared to other modalities, which explains differences in total intraoperative costs. The use of IGN, however, does not add extra expense compared to freehand TLIF when accounting for confounders on a regression analysis. This has major implications for clinical settings, where the use of IGN has been shown to reduce radiation exposure and pedicle screw misplacement.