Abdominal aortic calcification is associated with impaired fusion after elective spinal fusion.

Abstract

Background context: The interplay between vascular compromise and spinal pathology has been underexplored in the context of spinal fusion outcomes. Abdominal aortic calcification (AAC) is associated with various degenerative spinal conditions, potentially due to impaired perfusion. However, the relationship between AAC and the success of osseous fusion mass formation following spinal fusion remains unexplored.

Objectives: To investigate the association between AAC severity and fusion success following posterior lumbar spine fusion surgery.

Study design: Retrospective cohort study.

Patient population: Patients undergoing open posterior lumbar fusion between 2010 and 2021 at a single institution.

Outcome measures: Osseous posterolateral fusion (PLF) and interbody fusion (IBF) on computed tomography.

Methods: The institutional database was queried for patients who underwent open posterior spinal fusion and had postoperative CT scans at ≥12 months. Preoperative standing lateral lumbar radiographs were assessed for aortic calcification using the AAC-24 classification, which is a score between 0 (no AAC) to 24 (most severe AAC). Fusion success was evaluated using the Lenke (PLF) and Bridwell (IBF) classifications on CT. Binary outcomes of fusion success versus impairment were created for PLF and IBF and a combined outcome of either PLF and/or IBF for a third analysis. Multivariable logistic regression was used to identify predictors of impaired fusion, including AAC, age, sex, BMI, smoking, diabetes, number of levels fused, and fusion to the sacrum.

Results: A total of 207 patients were included for analysis. PLF impairment was observed in 28.5%, and IBF impairment in 22.7%. AAC was an independent predictor of impaired PLF (OR 1.10, 95% CI 1.02-1.20; p=.015) and combined PLF/IBF impairment (OR 1.16, 95% CI 1.06-1.29; p=.002). Multivariable analysis revealed, that each one-point increase in the AAC-24 score increased the odds of combined fusion impairment by 16%, and an increase of one standard deviation was associated with approximately a 2-fold increase in risk. Number of levels fused also predicted combined fusion impairment (OR 1.67, 95% CI 1.15-2.48; p=.009). No significant association was found between AAC and IBF impairment alone.

Conclusions: AAC is independently associated with posterolateral fusion impairment following spinal fusion surgery. routine preoperative assessment of AAC on lateral spine radiographs may help identify patients at higher risk for impaired fusion and guide surgical decision-making. Further studies are needed to validate these findings and evaluate strategies to mitigate this risk.