Who Gets Closure? Factors Affecting Access to Muscle Flap Closure in Spinal Fusion Patients

Introduction: Spinal fusion incurs risk of surgical site infection and wound dehiscence. Concomitant muscle flap closure may mitigate these risks. While benefits of muscle flap closure have been established, sociodemographic and hospital-level influences on access to this procedure remain unexplored.

Methods: Patients who received spinal fusions of two or more vertebral levels (n=130,666) were identified via ICD-10-PCS codes from the 2016-2018 National Inpatient Sample databases. The primary outcome was reception of muscle flap closure. 1:1 propensity score matching was conducted on age and comorbidity score as indicators of case severity, and number of spinal levels fused (fewer than or more than eight levels) and length of stay as indicators of surgical complexity. Binary logistic regression identified sociodemographic and hospital-level predictors of receiving muscle flap closure.

Results: 803 matched pairs were identified (n=1,606). Matched cohorts were comparable in age (p=0.29), comorbidity score (p=0.08), number of spinal levels fused (p=0.16), and length of stay (p=0.39). Medicaid payer status, residence in non-metropolitan counties, and reception of care at investor-owned hospitals were significant predictors of decreased likelihood of flap closure, whereas wealth in the highest income quartile was a significant predictor of increased likelihood of flap reception (p < 0.05).

Conclusion : Spinal fusion surgeries associated with Medicaid, lower-income, rural regions, and for-profit hospitals are associated with fewer muscle flap closures. These disparities may stem from multiple underlying factors including lack of access to specialized plastic surgery care and centralization of complex cases requiring muscle flap closure at quaternary care hospitals. Future analyses leveraging more granular datasets may match surgeries on specific pathologies and wound complication risk factors.