Lumbar Spine Endplate Sclerosis is a Protective Factor for Cage Subsidence in Minimally Invasive Transforaminal Lumbar Interbody Fusion

Study designRetrospective single-center cohort study.ObjectiveTo investigate the predictive value of preoperative endplate Hounsfield unit (HU) measurements for cage subsidence (CS) following minimally invasive transforaminal lumbar interbody fusion (MI-TLIF), and to propose threshold values for risk stratification.MethodsA total of 169 patients undergoing one- and two-level MI-TLIF with preoperative lumbar CT imaging were included. Endplate HU values were quantified within a 5-mm region of interest at the cage-endplate interface. Mild and severe CS was defined as 2-4 mm and ≥4 mm migration of the interbody cage into the adjacent vertebral endplate. Logistic regression analyses were employed to identify risk factors for CS.ResultsCS occurred in 39 of 464 endplates. Significantly lower L1 vertebral HU, reduced endplate HU at the surgical site, and obesity (BMI >25 kg/m²) were observed in the CS group. In multivariate analysis, obesity and endplate HU were independent predictor of CS (OR = 2.508; 95% CI, 1.135-5.546; OR = 0.989; 95% CI, 0.983-0.995). Among patients with L1 HU <117, those with endplate HU <221 had a significantly increased risk of CS (OR = 4.444; <i>P</i> = 0.0023). The area under the receiver operating characteristic curve for the combination of obesity (BMI >25 kg/m²) and endplate HU was 0.727 (95% CI 0.655-0.800).ConclusionsSurgical site endplate sclerosis at the surgical site may be a protective factor against CS following MI-TLIF. Preoperative endplate HU assessment may assist in identifying patients at risk of CS following MI-TLIF.