Introduction: Incidental durotomy is a complication observed in up to 17% of spinal surgeries, specifically ranging from 2 to 20% in lumbar degenerative spinal surgery. Correlational factors for incidental durotomy have been controversially published which include age greater than 65 years, obesity, female gender, degenerative spondylolisthesis, revision surgery, and surgeon experience. This prospective analysis was undertaken with the objective of demonstrating the impact of body mass index (BMI) on the incidence of durotomy during degenerative lumbar spinal procedures, and exploration of additional correlational factors.

Methods: Analysis was performed on a prospective observational registry of 506 patients undergoing lumbar spinal surgery for primary or recurrent lumbar degenerative disease from the National Neurosurgery Quality and Outcomes Database (N2QOD) from our institution. Statistical analysis was performed using GraphPad Prism 7.03, for calculation of descriptive statistics and Pearson correlation coefficients.

Results: The N2QOD lumbar spinal procedure database is composed of 506 patients prospectively analyzed with a mean age of 60.2 (+/- 13.8) years, mean body mass index 30.0 (+/- 5.52), lumbar spinal fusion procedure rate of 43.7% (221 cases), incidental durotomy 13.0% (66 cases), and female gender 51.2% (259 patients). BMI demonstrates a Pearson correlation value r = 0.097 (p = 0.029), suggestive of a small positive correlation with durotomy. Age (r = 0.073, p = 0.102) and female gender (r = 0.014, p = 0.748) were not significantly correlated with the incidence of durotomy. Lumbar fusion procedures (r = -0.116, p = 0.009) showed a weak negative correlation.

Conclusions: This study demonstrated a weakly positive correlation between durotomy and BMI. Literature on this topic demonstrates mixed results and within this series it is unclear if BMI significantly impacts durotomy rates. Similarly, other published correlative factors impacting the rate of durotomy were not demonstrated to be a significant contributor in this study.

Patient Care: This study provides insight to surgeons which can translate to more informed consent of patient by educating the surgeon on the appropriate correlative factors for the occurrence of a durotomy.

Learning Objectives: By the conclusion of this session, participants will be able to: 1) Describe the literature identified correlational factors with durotomy in lumbar spinal surgery. 2) Better forewarn patients that may be at a higher risk for durotomy during attainment of informed consent. 3) Discuss, in small groups, institutional practices and trends in durotomy incidence.

References: Adogwa O., et al. No difference in postoperative complications, pain, and functional outcomes up to 2 years after incidental durotomy in lumbar spinal fusion: a prospective, multi-institutional, propensity-matched analysis of 1,741 patients. Spine J 14(9):1828-34, 2014. Burks C., et al. Obesity is associated with an increased rate of incidental durotomy in lumbar spine surgery. Spine 40(7): 500-504, 2015 Ghobrial G., et al. Unintended durotomy in lumbar degenerative spinal surgery: a 10-year systematic review of the literature. Neurosurg Focus 39(4):E8, 2015 Klinger J., et al. Accidental Durotomy in Minimally Invasive Transforaminal Lumbar Interbody Fusion: Frequency, Risk Factors, and Management. Scientific Would Journal 2015, Article ID 532628 Takahashi T. et al. Incidental durotomy during lumbar spine surgery: risk factors and anatomic locations. J Neurosurg Spine 18:165-169, 2013.