Making wrong site surgery a "never event" in spinal deformity surgery by use of a "landmark vertebra" to eliminate variability in identifying a target vertebral level.

Purpose: Despite the introduction of "standardized counting" methods, errors in counting spinal levels and subsequent wrong-level surgery (WLS) remain critically important patient safety concerns. Previous work by our group has documented inconsistency in the identification of T12 despite the use of these systems including the Spinal Deformity Study Group (SDSG) conventions. To assist with consistent and repeatable identification of proposed preoperative surgical levels, the current study investigates a new strategy: utilization of a "landmark vertebra". It was hypothesized that individuals using a "landmark vertebra" strategy will achieve high concordance with target level identification between distinct time points as compared to conventional methods defining T12.

Methods: Survey participants analyzed 99 pre-op radiographs, identifying and naming a "landmark vertebra" with concise descriptions like "last bilaterally ribbed vertebra." They then noted the proposed lowest instrumented vertebra's (LIV) distance relative to landmark (i.e., one below landmark). After a waiting period, participants used their written descriptions of the landmark and distance to LIV to reidentify these vertebrae. Cohen's Kappa (k) was used to measure intra-rater agreeability. The landmark strategy was compared to our previous work evaluating consistency in defining T12 based on the SDSG system.

Results: All raters showed perfect to near-perfect agreement when re-identifying the landmark and target vertebrae (k = 0.819-1.00; Table 1A). Raters at all training levels had higher agreeability in naming the landmark vertebra and target when compared to raters at similar training levels defining T12 (k = 0.34-0.91; Table 1B). This high agreement across training demonstrates the strategy's versatility and generalizability.

Conclusion: Utilization of a landmark strategy proved to be highly effective in reducing intra-rater variability, with perfect to near-perfect agreement among all raters and consistently higher agreeability when compared to defining T12.

Level of evidence: Level II-prospective survey.