Fat Thickness as a Risk Factor for Infection in Lumbar Spine Surgery

Area of Science:

• Orthopedics
• Surgical Outcomes
• Medical Imaging

Background:

• Body mass index (BMI) is a common metric but does not reflect body fat distribution.
• Surgical site infections (SSIs) are a significant complication in lumbar spine procedures.
• Understanding risk factors for SSIs is crucial for improving patient safety and surgical success.

Purpose of the Study:

• To test the hypothesis that subcutaneous fat thickness is a superior predictor of SSI risk compared to BMI in lumbar spine surgery.
• To investigate the association between local fat thickness and SSI development.
• To compare the predictive value of fat thickness against established SSI risk factors.

Main Methods:

• Retrospective review of 149 adult patients undergoing lumbar spine procedures via a midline posterior approach.
• Analysis of known SSI risk factors including age, diabetes, smoking, obesity, albumin, procedure complexity, and operative time.
• Measurement of subcutaneous fat thickness using a novel automated technique.

Main Results:

• Fifteen SSIs occurred (10.1%) in the study cohort.
• Bivariate analysis revealed significant associations between SSI and BMI, obesity, and fat thickness.
• Multivariate analysis confirmed subcutaneous fat thickness as a significant independent predictor of SSI (P=.026), while BMI and obesity lost significance.

Conclusions:

• Local subcutaneous fat thickness is a more accurate indicator of SSI risk than BMI in lumbar spine surgery.
• Each 1-mm increase in fat thickness correlated with a 6% rise in SSI odds.
• Patients with fat thickness >50 mm faced a fourfold increased risk of SSI compared to those with <50 mm.