Increasing Nonconcurrent Overlapping Surgery Is Not Associated With Outcome Changes in Lumbar Fusion.

Background: There remains a paucity of literature on the impact of overlap on neurosurgical patient outcomes. The purpose of the present study was to correlate increasing duration of surgical overlap with short-term patient outcomes following lumbar fusion.

Methods: The present study retrospectively analyzed 1302 adult patients undergoing overlapping, single-level, posterior-only lumbar fusion within a single, multicenter, academic health system. Recorded outcomes included 30-day emergency department visits, readmission, reoperation, mortality, overall morbidity, and overall morbidity/surgical complications. The amount of overlap was calculated as a percentage of total overlap time. Comparison was made between patients with the most (top 10%) and least (bottom 40%) amount of overlap. Patients were then exact matched on key demographic factors but not by the attending surgeons. Subsequently, patients were exact matched by both demographic data and the attending surgeons. Univariate analysis was first carried out prior to matching and then on both the demographic-matched and surgeon-matched cohorts. Significance for all analyses was set at a value of <0.05.

Results: Within the whole population, increasing duration of overlap was not correlated with any short-term outcome ( = 0.41-0.91). After exact matching, patients with the most and least durations of overlap did not have significant differences with respect to any short-term outcomes ( = 0.34-1.00).

Conclusion: Increased amount of overlap is not associated with adverse short-term outcomes for single-level, posterior-only lumbar fusions.

Clinical Relevance: The present results suggest that increasing the duration of overlap during lumbar fusion surgery does not lead to inferior outcomes.