INTRODUCTION 
An incidental durotomy (ID) is a common intraoperative complication of spine surgery that can lead to persistent cerebrospinal fluid leakage, which may cause serious complications, including severe headaches, pseudomeningocele formation, nerve root entrapment, and intracranial hemorrhaging. Therefore, the purpose of this study was to clarify the independent risk factors for IDs during posterior open spinal surgery for lumbar degenerative diseases in adults.

METHODS
Between July 2010 and June 2020, we conducted a prospective observational study of adult patients (>17 years) who underwent posterior open spinal surgery for lumbar degenerative diseases in our hospital. Only the patients who underwent orthopedic spinal surgery were included in the study. We analyzed the associations between ID and multiple potential factors, including the patient’s age at the time of the surgery, sex, height, weight, body mass index, American Society of Anesthesiologists physical status classification, diabetes, hemodialysis, smoking, preoperative chronic steroid intake, type of procedure (laminectomy/herniotomy/fusion), use of posterior instrumentation, and past surgical history in the operated area. A Fisher’s exact test was used for the categorical variables and a Student’s t-test was used for the continuous variables. A multivariate analysis was performed to evaluate the risk factors for the occurrence of an intraoperative ID. The significant variables and the variables that correlated (P < 0.20) with SSI in the univariate analysis were entered into a stepwise multiple logistic regression model. Significance was set at P<0.05. In addition, the odds ratio (OR) and 95% confidence interval (CI) were calculated for each of the variables.

RESULTS
A total of 947 consecutive patients were enrolled (mean age: 65.0 years) in this study. The total incidence of IDs during the posterior surgeries was 7.2% (68 cases). The univariate analysis indicated that older age (P=0.019) was a significant risk factor for an ID. Older age and the factors with a P value <0.20 in the univariate analysis (diabetes [P=0.073], body height [P=0.110], smoking [P=0.129], preoperative chronic steroid intake [P=0.130]) were included in a multivariate analysis to further examine the risk factors for an ID. The results of the multivariate analysis revealed that older age (P=0.020, OR=1.025, 95%CI: 1.004-1.046) was the sole independent risk factor for the occurrence of an ID during posterior surgery. 

DISCUSSION

Knowing the risk factors that are associated with an increased risk of an ID is critical because IDs can cause large lacerations that cannot form sufficiently strong and watertight seals, which can lead to severe complications. Indeed, while repairing the dura after an ID is important, being conscious of the related risk factors and trying to avoid IDs is more important. The results of the present analysis can contribute to informing surgeons of the risk factors for IDs, and they can also be useful for counseling patients on the risks and complications that are associated with posterior open spine surgery for lumbar degenerative diseases.