Association between the cross-sectional area of paraspinal muscles and the spino-pelvic profile based on Roussouly classification / 中华骨科杂志

ABSTRACT

Objective:To investigate the association of the cross-sectional area of lumbar paraspinal muscle with the spino-pelvic profile based on Roussouly classification.Methods:From January 2019 to December 2019, 102 patients with lumbar disc herniation were collected, the index level included L 2, 3 in 3 cases(2.9%), L 3, 4 in 14 cases(13.7%), L 4,5 in 58 cases (56.9%), and L 5S 1 in 27 cases (23.5%). According to Roussouly classification, there were 29 cases of type I (28.4%), aged 57.0±11.7 years old (range 43 to 72 years old), 31 of type II (30.4%), aged 56.9±10.3 years old (range 40 to 70 years old), 28 of type III (27.5%), aged 53.5±12.9 years old (range 42 to 70 years old), and 14 of type IV (13.7%), aged 59.7±9.5 years old (range 51 to 70 years old). The clinical status of the patients were evaluated with the MOS 36-item short-form health survey (SF-36), Oswestry disability index (ODI) and visual analog scale (VAS). Select all patients with L 1, 2, L 2, 3, L 3, 4, L 4, 5 and L 5S 1 disc level axial MRI images, to measure the cross-sectional area (CSA) of paraspinal muscles (back extensor muscle and psoas muscle) and the CSA of intervertebral disc at each disc level, and calculate the relative cross-sectional area (RCSA the ratio of the CSA of muscles to that of the disc at the same level). One-way ANOVA was used to test the RCSA of the paraspinal muscles of the four groups, and then LSD- t test was used for pair wise comparisons to compare the RCSA of the paraspinal muscles in each group. Results:There was no significant difference in age ( F=1.067, P=0.367), female/male sex ratio ( χ2=2.412, P=0.491) and body mass index ( F=0.326, P=0.481). Roussouly type I group showed lower SF-36 score in both SF-36 PCS (31.5±6.5, F=3.207, P=0.047) and SF-36 MCS (33.9±5.7, F=3.409, P=0.031) compared with the other three types. In contrast, there were no significant differences in VAS Back Pain ( F=0.140, P>0.05), VAS leg pain ( F=0.622, P>0.05). and ODI scores ( F=1.075, P>0.05) among the types. At each level from L 1, 2 to L 5S 1, the RCSA of psoas muscle in Roussouly type IV (19.18±6.98, 35.36±10.37, 41.25±14.35, 61.58±12.03, 59.29±11.73) was significantly lower than that in patients with any other Roussouly type ( P<0.05), while no significant difference in the psoas RCSA among type I, type II and type III curves ( P>0.05). With regards to back extensor muscle, the RCSAs of back extensor muscle in Roussouly types I (135.32±19.86, 138.53±22.92, 125.06±21.44, 122.40±19.69, 110.87±18.08) and II (131.30±18.68, 136.39±24.87, 122.61±22.52, 121.10±20.47, 107.46±18.29) were significantly lower than those in Roussouly type III and IV at each level ( P<0.05), yet no significant difference between type I and II or between type III and IV. The ratio between the RCSA of back extensor muscle and psoas muscle in four types increased gradually from L 1, 2 to L 5S 1, with that being higher in type II (0.20±0.07, 0.33±0.09, 0.40±0.13, 0.58±0.11, 0.65±0.08) and lower in type IV (0.13±0.05, 0.24±0.07, 0.31±0.10, 0.47±0.10, 0.52±0.11). Conclusion:RCSA of paraspinal muscles varied among Roussouly types, suggesting a significant association between paraspinal muscles and the sagittal spino-pelvic alignment. Sagittal spino-pelvic alignment may be involved in the degeneration of paraspinal muscles.