Should Proximal Fixation Be at C2 or C3-C4? An Application of a Novel Operative Value Index for Posterior Cervical Decompression and Fusion

Introduction: There is clinical equipoise regarding the ideal upper instrumented vertebrae (UIV) for posterior cervical decompression and fusion (PCDF). Some surgeons instrument the C2 level, while others prefer anchoring at the subaxial C3/C4 vertebrae. To our knowledge, a true "value" (outcomes per dollar spent) comparison of instrumentation in the axial versus subaxial spine for PCDF has never been performed.

Methods: We retrospectively identified 275 long-segment (≥ 3-levels fused) PCDFs with available Neck Disability Index (NDI) scores at baseline and at 3-months postoperatively. C2 UIV (n=67) was compared to C3/C4 UIV (n=208). Time-driven activity-based costing (TDABC) was applied to identify the true intraoperative costs for each case. The Operative Value Index (OVI) was defined as the percent improvement in NDI score from baseline, per $1,000 spent intraoperatively. Multivariable linear regression analysis, accounting for confounders (including number of levels fused), was performed to compare intraoperative costs and OVI between C2 and C3/C4 UIV.

Results: The average total cost of a C2 construct was $13,751 ($5,247), compared to $10,778 ($2,237) for C3/C4 (p < 0.001). 40% of axial cases and 32% of subaxial cases achieved minimal clinically important difference (MCID), defined as ≥ 30% improvement in NDI from baseline. On multivariable regression analysis, C2 UI was associated with significantly higher total cost (beta-coefficient: $1,814 +/- 553, p=0.001), supply cost (beta-coefficient: $1,185 +/- $482, p=0.015) and personnel cost (beta-coefficient: $275 +/- $116, p=0.019) compared to C3/C4 UIV. However, there was no significant difference in OVI (p=0.155) between C2 and C3/C4 UIV.

Conclusion : While the C2 UIV construct incurred significantly higher intraoperative costs compared to C3/C4 UI, our analysis revealed no notable difference in the overall operative value with respect to neck disability when adjusting for confounding factors. These findings highlight the need for individualized surgical decision-making, where considerations of cost must be balanced with patient-specific factors and the surgeon's experience to optimize both outcomes and resource utilization.