Assessing Surgical Site Infection Risks in Posterior Cervical Decompression: The Role of Local Fat Thickness

Background: Local subcutaneous fat thickness has been identified as a significant predictor for the risk of surgical site infection (SSI) in lumbar spine procedures. Emerging research suggests its potential relevance in posterior cervical spine surgery as well. This study aims to further explore the connection, focusing on the comparative impact of Body Mass Index (BMI) and localized fat thickness at the C5 level on the risk of SSIs. Methods: This study presents a comprehensive retrospective analysis of patients treated with posterior cervical decompression without fusion for mono- or multisegmental cervical spondylotic myelopathy. From 2015 to 2022. Exclusions were made for minors and individuals who received posterior cervical instrumentation. Measurements of localized nuchal and fat thickness at the C5 level were taken. Patient charts provided data on demographics, BMI, diabetic status, smoking history, previous surgical history, the extent of surgery (number of operated levels), and duration of hospital stay. A combination of univariate and multivariate analysis was employed to identify significant predictors of SSIs. Results: From the 346 patients who qualified for the study, 20 (5.8%) experienced SSIs. Those with SSIs generally had higher BMIs (median 29 vs. 27, p=0.032), greater nuchal fat thickness (median 27mm vs. 23mm, p=0.012), and more extensive surgeries (75% had multiple levels operated compared to 55% in the non-SSI cohort, p=0.001). Additionally, the occurrence of SSI resulted in a prolonged hospital stay (median 12 days vs. 7 days, p≤0.001). However, in multivariate logistic regression, nuchal fat thickness was not a significant predictor, whereas BMI and the number of operated levels were confirmed as substantial predictors of SSI (OR=1.095, CI: 1.005 to 1.192, p= 0.038 and OR=2.089, CI: 1.3 to 3.357, p= 0.002 respectively). Conclusion: This research indicates that contrary to initial assumptions, localized fat thickness at the C5 level is not a significant predictive factor for SSI post posterior cervical decompression. Instead, it underscores the importance of BMI and the extent of surgical intervention as considerable, quantifiable risk factors for SSIs. These findings can guide more effective preoperative assessments and targeted interventions to mitigate SSI risks in posterior cervical decompression surgeries.