ABSTRACT
Objective:To explore the risk factors of surgical site infection after posterior lumbar interbody fusion and internal fixation in elderly patients with lumbar degenerative diseases.Methods:The clinical data of elderly patients who underwent posterior lumbar interbody fusion and internal fixation for degenerative diseases of lumbar spine in Department of Orthopedics, Shanxi Bethune Hospital from January 2019 to December 2021 were retrospectively analyzed.Eighteen elderly patients with postoperative incision infection were included into the infection group, and according to the ratio of 1∶3, 54 elderly patients without incision infection during the same period were randomly selected and included in the non-infection group.The general data of patients, surgical related data and perioperative laboratory indexes were compared between groups using univariate analysis.The screened out indicators with close correlation with incision infection and with significantly statistical significance were included in binary Logistic regression analysis.Risk factors related to postoperative incision infection were analyzed by receiver operating characteristic curve(ROC).The quantitative data of risk factors related to postoperative incision infection were selected for receiver operating characteristic curve(ROC)analysis.Results:When comparing the infected versus non-infected groups, the operative time was(197.1±39.5)min vs.(171.4±37.2)min, preoperative lymphoid count was(1.6±0.5)×10 9/L vs.(1.9±0.6)×10 9/L, and postoperative neutrophil count was[(7.2(6.2-9.5)×10 9/L vs.6.3(4.8-7.2)×10 9/L], percentage of neutrophils(82.5±8.8), % vs.(71.1±6.7), percentage of lymphocytes(1.1±0.6)×10 9/L vs.(1.7±0.7)×10 9/L, percentage of lymphocytes(11.0±5.6)% vs.(19.8±6.0)%, number of neutrophils vs.Lymphocyte count ratio(NLR)[8.5(5.2-15.0) vs.3.6(2.6-4.9)]and serum albumin concentration(31.4±2.5)g/L vs.(33.3±2.4)g/L, all P<0.05).Logistic regression analysis showed that diabetes mellitus( OR=6.649, 95% CI: 1.233-35.853), operation time( OR=1.025, 95% CI: 1.004-1.047), and percentage of postoperative neutrophils( OR=1.261, 95% CI: 1.125-1.414)were independent risk factors of incision infection after posterior interbody fusion and internal fixation in patients with lumbar degenerative diseases(all P<0.05).ROC analysis showed that the area under the curve of operation time was 0.680, and the cut-off value was 177.5 min.The area under the curve of the percentage of neutrophils after operation was 0.841, and the cut-off value was 78.85%. Conclusions:In patients with posterior interbody fusion and internal fixation for lumbar degenerative diseases complicated with diabetes, long operation time, and increased percentage of neutrophils after surgery can independently increase the risk of incision infection.