Analysis of the association between lumbar paraspinal muscle atrophy, facet joint degeneration, and degenerative lumbar scoliosis.

objectiveTo analyze the correlation between paraspinal muscle atrophy, facet joint degeneration, and degenerative scoliosis (DS).

methodsA retrospective study included 231 chronic low back pain patients from Zhongda Hospital Affiliated to Southeast University (January 2023-January 2024). Radiographic diagnosis assigned 150 patients to DS group (subclassified into mild [n = 72], moderate [n = 56], severe [n = 22]) and 81 to non-DS control group. Using T2-weighted MRI at L3-S1 levels, ImageJ software measured multifidus (MF) and erector spinae (ES) cross-sectional area (CSA) and functional muscle ratio (LCSA/GCSA). Surgimap software quantified facet joint angle (FJA), facet overhang (FO) length, and facet joint space width (FJSW). Logistic regression analyzed risk factors with ROC curves determining diagnostic thresholds.

resultsThe non-DS group demonstrated a significantly higher proportion of males (P = 0.023) and greater bone mineral density (P = 0.043) compared to the DS group. Regarding paraspinal muscle parameters, the non-DS group exhibited significantly larger MF CSA, MF + ES CSA, and LCSA/GCSA at the L3/4, L4/5, and L5/S1 levels, as well as a larger ES CSA at the L3/4 level (all P < 0.05). Conversely, the ES CSA at the L5/S1 level was significantly smaller in the non-DS group. For facet joint parameters, the non-DS group showed significantly smaller FJA, FO Length at the L3/4, L4/5, and L5/S1 levels, and smaller FJSW at the L3/4 and L4/5 levels (all P < 0.05). Within the DS group, significant differences were observed between the convex and concave sides at all L3-S1 levels for LCSA/GCSA, MF CSA, ES CSA, FJA, FO Length, and FJSW (all P < 0.05). With increasing severity of DS, there was a progressive decrease in LCSA/GCSA, MF CSA, and ES CSA, and a progressive increase in FJA and FO Length across the L3-S1 levels (all P < 0.01). Post-hoc analysis revealed significant differences in the majority of muscle parameters between severe DS and mild/moderate DS (P < 0.05). Correlation analysis indicated that, except for FJSW at L5-S1 (P = 0.526), the Cobb angle was negatively correlated with MF CSA, ES CSA, LCSA/GCSA, and FJSW, and positively correlated with FJA and FO Length (all P < 0.001). In both the DS and non-DS groups, most LCSA/GCSA and other CSA measurements demonstrated no significant correlations with FJA, FO length, and FJSW. Among the few statistically significant correlations observed, all were weak (rho < 0.30). Multivariate logistic regression analysis identified the following risk-associated factors for DS: lower BMD (OR = 0.802, P = 0.032), reduced LCSA/GCSA (OR = 0.005, P = 0.003), smaller MF CSA (OR = 0.969, P = 0.027), smaller ES CSA (OR = 0.973, P = 0.014), larger FJA (OR = 1.075, P = 0.016), and greater FO length (OR = 1.067, P = 0.001). ROC analysis yielded AUCs/cut-offs: BMD (0.581/- 0.900 T-score), LCSA/GCSA (0.712/0.805), MF CSA (0.608/635 mm

conclusionDS patients demonstrate progressive paraspinal muscle atrophy, sagittal-oriented facet joints, and advanced facet degeneration correlating with scoliosis severity. Diagnostic thresholds indicating DS probability are BMD < - 0.900 T-score, LCSA/GCSA < 0.805, MF CSA < 635 mm