Vertebral bone quality score independently predicts cage subsidence following transforaminal lumbar interbody fusion

BACKGROUND CONTEXT: Cage subsidence following transforaminal lumbar interbody fusion (TLIF) has been associated with poor bone quality. Current evidence suggests that the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score correlates with poor bone quality. PURPOSE: To our knowledge, this is the first study to assess whether the VBQ score can predict the occurrence of postoperative cage subsidence after TLIF surgery. DESIGN/SETTING: Retrospective single-center cohort. PATIENT SAMPLE: Patients undergoing single-level TLIF for degenerative spine disease between February 2014 and October 2021. OUTCOME MEASURES: Extent of subsidence. METHODS: Demographic, procedure-related, and radiographic data were collected for study patients. VBQ scores were determined from preoperative T1-weighted MRI. Subsidence was defined as ≥2 mm of migration of the cage into the superior or inferior end plate or both. Univariate and multivariate logistic regression were used to determine the correlation between potential risk factors for subsidence and actual subsidence rates. RESULTS: Subsidence was observed among 42 of the 74 study patients. The mean VBQ scores were 2.9±0.5 for patients with subsidence and 2.5±0.5 for patients without subsidence. The difference among groups was significant (p=.003). On multivariate logistic regression, a higher VBQ score was significantly associated with an increased risk of subsidence (OR=1.5, 95% CI=1.160–1.973, p=.004) and was the only significant independent predictor of subsidence after TLIF. CONCLUSION: We found that a higher VBQ score was significantly associated with cage subsidence following TLIF. The MRI-VBQ score may be a valuable tool for assisting in identifying patients at risk of cage subsidence following TLIF.