Subcutaneous Fat Thickness on Erect Radiographs Is a Predictor of Infection Following Elective Posterior Lumbar Fusion

Abstract

Background: Posterior lumbar fusions are a common and successful procedure, yet surgical site infection (SSI) is still prevalent and causes significant morbidity. Obesity is a well-established risk factor for SSI. Still, the accuracy of the body mass index (BMI) caused some to suggest other metrics that are more representative of the thickness of the soft-tissue envelope in the surgical site.Methods: A retrospective review of all cases that developed SSI following posterior lumbar fusion over the past 5 years was done. An age and gender-matched control group was formed from the lumbar fusion cases that did not develop SSI. Demographic and clinical data were collected, and morphometric measurements of the soft-tissue envelope were performed at the level of L4 for all cases on standing x-ray imaging and magnetic resonance imaging (MRI).Results: A total of 366 patients underwent posterior lumbar fusion, 26 of whom developed SSI. BMI and skin to spinous process measurements on x-ray imaging-not MRI-were found to be significantly associated with SSI. Regression analysis further confirmed the strength of the association.Conclusion: While BMI and MRI measurements are useful, wound depth measurements on x-ray imaging can be predictive of SSI in lumbar fusion cases.Clinical Relevace: Wound depth measurements are predictive of lumbar wound infection. The information within this study can help surgeons better predict and manage infections of posterior lumbar wounds.

Acute Surgical Site Complications in Direct Anterior Total Hip Arthroplasty: Impact of Local Subcutaneous Tissue Depth and Body Mass Index

“…They found BMI and soft tissue depth to be significantly associated with SSI. [ 19 ] In another study on patients undergoing lumbar spine procedures through a midline posterior approach, there was a 6% increased risk of infection for every 1 mm thickness of subcutaneous fat (measured on magnetic resonance imaging), as well as a 4-fold increase in risk of infection with greater than 50 mm of posterior lumbar back fat thickness. [ 9 ] This has also been proven in patients who underwent posterior cervical spine fusion.…”

Correlation of Lumbar Spine Fat Thickness and Surgical Site Infection in Degenerative Lumbar Spine Surgery

“…However, there is an insufficient number of studies internationally and only one to our knowledge nationally that studied the correlation between lumbar fat thickness and SSI. In the national study that was published in the International Journal of Spine Surgery on July 2022, they reported a significant association of SSI with subcutaneous fat thickness measured on erect radiographs 16 . Another multicenter research assessed adipose index correlation with deep SSI and concluded that increased adipose tissue is an independent risk that was significantly associated with developing deep SSI.…”