Utilizing MRI and CT to identify risk factors associated with cage subsidence

To identify risk factors associated with cage subsidence (CS) following single segment transforaminal lumbar interbody fusion (TLIF) and unilateral biportal endoscopic lumbar interbody fusion (ULIF) and to compare the predictive performance of various bone quality assessment methods using MRI and CT images.

A total of 226 patients from 2021 to 2023 who underwent ULIF/TLIF because of lumbar disc herniation and lumbar spinal stenosis were enrolled. The subsidence of the cage into the vertebral body exceeding 2 mm was defined as CS and diagnosed using CT scans. Immediate endplate destruction (IED) was defined by CT and VBQ was measured through T1-weighted lumbar MRI. The independent sample t-test was employed to examine the risk factors associated with CS. Additionally, risk factors associated with CS were identified using logistic regression analysis. Lastly, the comparative predictive values were assessed through ROC curve analysis.

Logistic regression analysis revealed that increased postoperative posterior disc height (PPDH), higher segmental VBQ scores, higher mean VBQ (M-VBQ) scores, decreased segmental HU values, decreased mean HU (M-HU) values and immediate endplate destruction (IED) were associated with the occurrence of CS. The area under the curve (AUC) of the VBQ score was higher than that of the HU value, both in segment and in average.

The incidence of CS was lower in ULIF compared to TLIF. High VBQ scores, low HU values, high PPDH and the presence of IED were associated with an increased risk of CS. Notably, the predictive value of both VBQ scores and HU values were high for CS, with the former potentially outperforming the latter.