Effects of MRI-based EBQ and VBQ on adjacent segment degeneration and clinical outcomes after PLIF

To explore the main and interaction effects of EBQ and VBQ on postoperative ASD, cage subsidence and clinical outcomes in L4/5 PLIF patients. A total of 186 L4/5 PLIF patients were enrolled and followed up for at least 2 years. Using a 2 × 2 factorial design, patients were stratified into four groups according to their EBQ and VBQ scores. Preoperative baseline data, follow-up imaging parameters, and functional scores were collected to analyze EBQ/VBQ’s main and interaction effects on primary (ASD, cage subsidence) and secondary outcomes. No significant differences in preoperative baseline data were noted among the four 2 × 2 factorial design-stratified groups. VBQ and EBQ showed a significant interaction on ASD and cage subsidence incidence, with higher rates in the high-VBQ group. High-EBQ elevated rates only under high-VBQ condition. VBQ and EBQ exerted significant main effects on PT, FSA, LL and JOA scores without interaction, and only EBQ affected SS significantly. Neither VBQ nor EBQ affected disc height, ROM, Pfirrmann grades, VAS-leg scores at L3/4 and L5/S1 segments. VBQ and EBQ interacted significantly on VAS-back and ODI scores. In high-VBQ status, high-EBQ patients had higher scores than low-EBQ ones, and the same trend held in high-EBQ status. EBQ and VBQ exert a significant interaction effect on ASD, cage subsidence, VAS-back and ODI scores after L4/5 PLIF, with VBQ serving as the core regulatory factor.