Comparative analysis of the correlation between paraspinal muscles fat infiltration and vertebral bone quality in patients with lumbar degenerative diseases.

Purpose: This study aimed to comprehensively evaluate the association between paraspinal muscle fat infiltration (FI) and three MRI-based vertebral bone quality indicators-Vertebral Bone Quality (VBQ), Modified VBQ (MVBQ), and Endplate Bone Quality (EBQ)-in patients with lumbar degenerative diseases (LDD), and to compare their diagnostic and prognostic implications.

Methods: A retrospective analysis included 261 patients undergoing transforaminal lumbar interbody fusion (TLIF) for LDD. Paraspinal muscle parameters-total cross-sectional area (TCSA), functional CSA (FCSA), relative FCSA (rFCSA), and fat infiltration rate (FIR)-were obtained from preoperative MRI. VBQ, MVBQ, and EBQ scores were also calculated. Patients were stratified into high and low FI groups based on FIR quartiles. Correlation and multivariable regression analyses were performed, and diagnostic performance was assessed using Receiver Operating Characteristic (ROC) curves, Clinical outcomes (Oswestry Disability Index (ODI), Visual Analogue Scale (VAS)) were followed up for 2 years.

Results: Patients with high FI exhibited significantly elevated VBQ (3.41 vs. 3.01, p < 0.001), MVBQ (3.47 vs. 2.91, p < 0.001), and EBQ (3.31 vs. 2.97, p = 0.001) scores compared to the normal FI group. FIR correlated positively with all bone quality indices, with the strongest association for MVBQ (r = 0.432, p < 0.001). MVBQ demonstrated superior diagnostic performance (AUC = 0.70) compared to VBQ (AUC = 0.64) and EBQ (AUC = 0.53). At 2-year follow-up, high FI patients had worse ODI scores (11.61 vs. 10.57, p = 0.031), though no differences in VAS were observed.

Conclusion: Our study established a significant association between paraspinal muscles FI and the bone quality of various regions of the vertebrae, as well as prognosis undergoing surgery for LDD patients. MVBQ may serve as a reliable and practical preoperative marker for musculoskeletal degeneration in patients with LDD, guiding individualized risk stratification and rehabilitation planning.