2012 Young Investigator Award winner: The distribution of body mass as a significant risk factor for lumbar spinal fusion postoperative infections

Abstract

Study design: A retrospective review.

Objective: The purpose of this study was to determine the role in body habitus and weight distribution on developing a surgical site infection (SSI).

Summary of background data: SSI after lumbar spine surgery remains a significant cause of morbidity. The literature demonstrates an increased risk of postoperative infections associated with obesity, diabetes, and multilevel surgeries.

Methods: A retrospective review was performed on a consecutive cohort of 298 adult patients who underwent lumbar spine fusion surgeries between 2006 and 2008 at the Duke University Medical Center. Previously identified risk factors (i.e., number of levels, diabetes, body mass index [BMI]) were collected, as well as the horizontal distance from the lamina to the skin surface (measured at L4) and thickness of subcutaneous fat at the surgical site.

Results: Among the 298 patients, 24 (8%) had postoperative infections. Of the previously identified risk factors, number of levels (P = 0.0078) was found to be significantly associated with infections, whereas BMI (P = 0.16) and diabetes (P = 0.13) were found not to be statistically significant. Obesity (BMI ≥30) (P = 0.025), skin to lamina distance (P = 0.046), and thickness of the subcutaneous fat (P = 0.035) were found to be significant risk factors for SSI.

Conclusion: Our findings suggest that in obese patients, the distribution of body mass is more predictive of SSI than the absolute BMI and deserves attention in preoperative evaluation.