Objective:To investigate the changes of paraspinal muscles in patients with degenerative lumbar scoliosis (DLS) and its correlation with lumbar kyphosis.Methods:The clinical data of 67 female patients with degenerative lumbar scoliosis, with an average of 65.4±5.6 years old (rang 52-83 years old), were retrospectively analyzed. There were 35 patients of DLS with lumbar degenerative kyphosis (LDK) in the DLS+LDK group, with an average of 64.60±5.40 years old (rang 52-75 years old), and 32 patients of lumbar scoliosis without lumbar kyphosis in the DLS group, with an average of 66.22±5.8 years old (rang 55-83 years old). The cross-sectional area (CSA) and the percentage of fat infiltration area (FIA%) of erector spinae and multifidus muscles of the 5 intervertebral disc levels (from L 1-2 to L 5S 1) were measured by MRI using Image J software (ver. 1.51 k, National Institutes of Health, USA). The curve direction, Cobb angle, sagittal vertical axis (SVA), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) were evaluated and recordedin both groups using an anteroposterior radiograph in the standing position, and the correlation between the changes of paraspinal muscles and these factors was analyzed. Results:The TLK, LL, and SVA values of the DLS+LDK group (11.85°±7.89°, -9.35°±8.70° and 70.16±76.94 mm) were higher than those of the DLS group (7.47°±5.06°, -26.46°±10.26° and 39.45±38.18mm) ( t=2.73, P=0.008; t=7.38, P<0.001; t=2.10, P=0.041). The TK, PI, and SS values of the DLS+LDK group (16.36°±13.52°, 42.49°±11.70° and 11.89°±10.03°) were lower than those of the DLS group (23.60°±10.23°, 49.38°±11.92° and 21.21°±8.28°) ( t=2.45, P=0.017; t=2.38, P=0.020; t=4.13, P<0.001). The differences of Cobb and PT were not statistically significant between the two groups. The cross-sectional areas of L 1-2, L 2-3, L 3-4 intervertebral disc levels of erector spinae of the DLS+LDK group (1 328.36±339.16 mm 2, 1 331.98±305.76 mm 2 and 12 53.58±275.86 mm 2) were lower than those of the DLS group (1 564.16±312.68 mm 2, 1 574.80±325.92 mm 2 and 1 427.18±278.82 mm 2) ( t=0.40, P=0.004; t=0.81, P=0.002; t=0.306, P=0.013). The cross-sectional areas of L 1-2, L 2-3, L 3-4, L 4-5 intervertebral disc levels of multifidus muscles of the DLS+LDK group (225.07±59.80 mm 2, 228.38±87.44 mm 2, 436.40±117.99 mm 2 and 666.55±184.13 mm 2) were lower than those of the DLS group (264.28±44.27 mm 2, 384.85±75.52 mm 2, 576.10±109.92 mm 2 and 801.52±145.83 mm 2) ( t=0.21, P=0.004; t=0.42, P<0.001; t=0.52, P<0.001; t=0.37, P=0.002). The differences of FIA% of erector spinae and multifidus muscles at all lumbar spine levels were not statistically significant between the two groups. The cross-sectional areas of L 1-2, L 2-3, L 3-4 intervertebral disc levels of erector spinae and L 1-2, L 2-3, L 3-4, L 4-5 intervertebral disc levels of multifidus muscles of the two groups were negatively correlated with LL values ( r=-0.37, P=0.002; r=-0.34, P=0.005; r=-0.21, P=0.049; r=-0.34, P=0.005; r=-0.61, P<0.001; r=-0.65, P<0.001; r=-0.55, P<0.001), and positively correlated with SS ( r=0.42, P<0.001; r=0.37, P=0.002; r=0.27, P=0.027; r=0.38, P=0.001; r=0.53, P<0.001; r=0.46, P<0.001; r=0.42, P<0.001). The cross-sectional areas of L 3-4 intervertebral disc levels of erector spinae and L 1-2, L 2-3 intervertebral disc levels of multifidus muscles of the two groups were positively correlated with PI ( r=0.25, P=0.039; r=0.33, P=0.006; r=0.35, P=0.004). There was no correlation between the FIA% of erector spinae and multifidus muscles at all lumbar spine levels and the sagittal and pelvic parameters in both groups. Conclusion:Paravertebral muscle atrophy is more obvious in patients with degenerative lumbar scoliosis with lumbar kyphosis, which may be related to the reduce of lumbar lordosis and sacral slope. Patients with lumbar scoliosis with a smaller PI are more likely to experience paravertebral atrophy and increased loss of lumbar lordosis, and ultimately leading to lumbar kyphosis.