Overlapping single-level lumbar fusion and adverse short-term outcomes

There is a paucity of research on the safety of overlapping surgery. The purpose of this study was to evaluate the impact of overlapping surgery on a homogenous population of exactly matched patients undergoing single-level, posterior-only lumbar fusion.

The authors retrospectively analyzed case data of 3799 consecutive adult patients who underwent single-level, posterior-only lumbar fusion during a 6-year period (June 7, 2013, to April 29, 2019) at a multihospital university health system. Outcomes included 30-day emergency department (ED) visit, readmission, reoperation, and morbidity and mortality following surgery. Thereafter, coarsened exact matching was used to match patients with and without overlap on key demographic factors, including American Society of Anesthesiologists (ASA) class, Charlson Comorbidity Index (CCI) score, sex, and body mass index (BMI), among others. Patients were subsequently matched by both demographic data and by the specific surgeon performing the operation. Univariate analysis was carried out on the whole population, the demographically matched cohort, and the surgeon-matched cohort, with significance set at a p value < 0.05.

There was no significant difference in morbidity or any short-term outcome, including readmission, reoperation, ED evaluation, and mortality. Among the demographically matched cohort and surgeon-matched cohort, there was no significant difference in age, sex, history of prior surgery, ASA class, or CCI score. Overlapping surgery patients in both the demographically matched cohort and the matched cohort limited by surgeon had longer durations of surgery (p < 0.01), but no increased morbidity or mortality was noted. Patients selected for overlap had fewer prior surgeries and lower ASA class and CCI score (p < 0.01). Patients with overlap also had a longer duration of surgery (p < 0.01) but not duration of closure.

Exactly matched patients undergoing overlapping single-level lumbar fusion procedures had no increased short-term morbidity or mortality; however, duration of surgery was 20 minutes longer on average for overlapping operations. Further studies should assess long-term patient outcomes and the impact of overlap in this and other surgical procedures.