Degenerative characteristics and biomechanical effects of paravertebral muscles in patients with degenerative lumbar scoliosis / 中国医师进修杂志

ABSTRACT

Objective:To investigate the degenerative characteristics and biomechanical effects of paravertebral muscles in patients with degenerative lumbar scoliosis.Methods:The clinical data of 236 patients with degenerative lumbar scoliosis from January 2016 to January 2020 in Yuncheng Central Hospital of Shanxi Province were retrospectively analyzed. All patients underwent lumbar X-ray and MRI measurement, and the indexes included coronal scoliosis Cobb angle, rotation classification of apical vertebra, cross-sectional area (CSA) of the apical vertebra upper and lower intercalated disc plane, fatty infiltration rate (FIR) of psoas major and back extensor muscle group (including erector spinae and multifidus muscle), cross-sectional area difference index (CDI) and fatty infiltration difference (FID). The correlation between paravertebral muscle degeneration and coronal scoliosis Cobb angle was evaluated.Results:The coronal scoliosis Cobb angle of 236 patients was 10.4° to 57.8° (18.72 ± 6.44)°; there were no statistical differences in coronal scoliosis Cobb angle and rotation classification of apical vertebra between different sex, scoliosis direction and apical vertebra position ( P>0.05). In the apical vertebra upper intercalated disc plane, the concave side CSA of psoas major muscle was significantly higher than convex side: (3.82 ± 1.06) cm 2 vs. (3.68 ± 1.01) cm 2, the concave side CSA of multifidus muscle, back extensor muscle group and paraspinal muscle group (including psoas major muscle, quadratus lumborum, erector spinae and multifidus muscle) was significantly lower than convex side: (9.80 ± 2.14) cm 2 vs. (10.46 ± 2.60) cm 2, (18.18 ± 3.03) cm 2 vs. (19.79 ± 3.22) cm 2 and (25.25 ± 5.06) cm 2 vs. (27.86 ± 6.90) cm 2, and there were statistical differences ( P<0.05 or <0.01); there were no statistical differences in CSA of quadratus lumborum and erector spinae between concave side and convex side ( P>0.05). In the apical vertebra lower intercalated disc plane, the concave side CSA of psoas major muscle and quadratus lumborum was significantly higher than convex side: (6.62 ± 3.09) cm 2 vs. (6.40 ± 3.23) cm 2 and (4.58 ± 0.57) cm 2 vs. (4.45 ± 0.64) cm 2, the concave side CSA of multifidus muscle and back extensor muscle group was significantly lower than concave side: (9.49 ± 3.10) cm 2 vs. (10.32 ± 4.06) cm 2 and (19.31 ± 4.36) cm 2 vs. (20.54 ± 5.60) cm 2, and there were statistical differences ( P<0.01 or <0.05); there was no statistical difference in CSA of erector spinae and paraspinal muscle group between concave side and convex side ( P>0.05). In apical vertebra upper and lower intercalated disc plane, the concave side FIR of back extensor muscle group was significantly higher than convex side: (31.83 ± 11.04)% vs. (24.37 ± 12.76)% and (38.62 ± 10.09)% vs. (31.80 ± 8.23)%, and there was statistical difference ( P<0.01); there was no statistical difference in FIR of psoas major muscle between concave side and convex side ( P>0.05). Pearson linear correlation analysis result showed that CDI of multifidus muscle, back extensor muscle group, paraspinal muscle group and FID of back extensor muscle group were positively correlated with coronal scoliosis Cobb angle (apical vertebra upper intercalated disc plane: r = 0.94, 0.70, 0.86 and 0.90, P<0.01; apical vertebra lower intercalated disc plane: r = 0.92, 0.94, 0.81 and 0.66, P<0.01); the CDI of psoas major muscle in apical vertebra lower intercalated disc plane was positively correlated with coronal scoliosis Cobb angle ( r = 0.73, P<0.01); there was no correlation between CDI of psoas major muscle in apical vertebra upper intercalated disc plane and coronal scoliosis Cobb angle ( r = 0.17, P>0.05). In patients with apical vertebra located in L 2 and L 3, the CSA of psoas major muscle and quadratus lumborum in apical vertebra lower intercalated disc plane was significantly higher than that in apical vertebra upper intercalated disc plane, and there was statistical difference ( P<0.01); in patients with apical vertebra located in L 2, the concave side CSA of erector spinae in apical vertebra lower intercalated disc plane was significantly higher than that in apical vertebra upper intercalated disc plane, and there was statistical difference ( P<0.01). Conclusions:The biomechanical effects of lumbar flexion/ back extensor muscle group should be different in the process of disease progression in patients with degenerative lumbar scoliosis, in which the back extensor muscle group can effectively inhibit the degenerative disease. The protection of paravertebral muscle group function should be placed in an important role in degenerative lumbar scoliosis treatment.