Correlation of Lumbar Spine Fat Thickness and Surgical Site Infection in Degenerative Lumbar Spine Surgery

Introduction: Surgical site infection (SSI) is a serious and common complication following any surgery. Patientsundergoing lumbar surgery have a higher risk for SSI. Therefore, it is essential to accurately identifythe risk factors of SSIs to prevent them. There is an insufficient number of studies internationally andonly one to our knowledge nationally that studied the correlation between lumbar fat thickness andSSI in patients undergoing lumbar spine surgery. Our aim was to identify the correlation betweenlumbar fat thickness and SSI and determine its predictive value compared to other risk factors inpredicting the incidence of SSI. Methods: This retrospective cohort study involved all patients aged 18 and above who underwent primary elective degenerative lumbar spine surgery in National Guard Health Affairs (NGHA) from 2016 to 2020 at King Abdulaziz Medical City (KAMC), Riyadh, Saudi Arabia. All trauma and oncology cases, patients with previous spine surgery, non-instrumented cases, and emergency cases without preoperative radiological images were excluded. The pre-operative and post-operative measurements were assessed using the sagittal MRI images on the T1 view to measure the fat length of the lumbar spine from L2 to S1. Two observers evaluated the films, and the average measurement was documented for each level. Results: 151 patients were included in our study, four of whom developed SSI. When comparing the demographics of both groups, BMI was found to be a significant variable between both groups, with a P-value of 0.013. However, there was no significance regarding age, gender, DM, HTN, steroid use, and level of stay for each group. Furthermore, there was no significance in all vertebrae levels except for L4 fat thickness, which was significantly higher in the SSI group with a P value of 0.0264. Conclusion: Surgical site infection (SSI) is a serious and common complication following any surgical operation. Patients undergoing lumbar surgery have a higher risk for SSI. In this study, we concluded that an increased L4 fat thickness was a significant predictor of SSI.