Correlation between changes of cervical longus and cervical extensor muscles and clinical efficacy after anterior cervical discectomy and fusion / 中华骨科杂志

ABSTRACT

Objective:To evaluate the volume changes of cervical longus and cervical extensor after anterior cervical discectomy and fusion (ACDF), and the correlation with the clinical efficacy of patients.Methods:All of 57 patients with cervical spondylotic myelopathy who underwent single-segment ACDF surgery from January 2013 to December 2018 were analyzed. The follow-up time was 23.0±4.8 months (range 16-34 months). All included subjects underwent MR examination within 1 week before operation and 3rd, 12th months after operation and at the last follow-up. The axial section cross section area (AxCSA) of the cervical longus and the ratio of length to short diameter line (RLS) at the level of each disc of C 2-C 7 were measured on the axial T2WI. Calculate the volume of the cervical longus based on the layer thickness. At the same time, measure the cervical extensor cross-sectional area (CESA) of the same level including the multifidus, cervical semispinous muscle, semispinous head, splinter head, and cervical splinter muscles, and compare CESA with the corresponding vertebral cross-sectional area (VBA). The ratio is analyzed as the volume of the neck extensor muscle, namely CESA/VBA. At the 3rd and 12th months after operation and at the last follow-up, the axial pain was assessed by visual analogue scale (VAS) for assessing pain, and the modified Japanese Orthopedic Association score (mJOA) and the neck dysfunction index (NDI) were used to assess the functional status of the cervical spine. Analyze the morphological changes of thecervical longus and extensor cervical muscles before and after the operation and during the follow-up period, and analyze the correlation with VAS, mJOA, and NDI. Results:Compared with the preoperative period, the average AxCSA of the surgical segment decreased at the 3rd and 12th months after the operation and at the last follow-up. The difference was statistically significant ( F=24.113, P<0.05), which was changed from 140.84±19.51 mm 2 respectively reduce to 117.74±17.15 mm 2 ( t=6.714, P<0.05), 116.37±18.67 mm 2 ( t=6.841, P<0.05) and 116.27±18.65 mm 2 ( t=6.873, P<0.05). Compared with preoperatively, they were reduced by 16.40%, 17.37% and 17.45%, respectively, while the average RLS of surgical segments increased slightly, and the difference was statistically significant ( F=22.612, P<0.05), which increased from preoperative 1.97±0.67 to 2.73±0.60 (38.58% increased, t=6.380, P<0.05), 2.82±0.64 (43.15% increased, t=6.926, P<0.05) and 2.74±0.62 (39.09% increased, t=6.368, P<0.05). The volume of thecervical longus of the patients decreased after the operation, and the difference was statistically significant ( F=64.511, P<0.05), which decreased from 8853.48±458.65 mm 3 before the operation to 7834.53±461.59 mm 3 (11.51% decreased, t=11.822, P<0.05), 7926.42±456.24 mm 3 (10.47% decreased, t=10.819, P<0.05), 7892.38±450.78 mm 3 (10.86% decreased, t=11.283, P<0.05). There were no statistically significant differences in the non-surgical segment AxCSA, RLS and the volume of thecervical longus at the 3rd and 12th months after surgery and the last follow-up ( P>0.05). There was no statistically significant difference of CESA and CESA/VBA compared to preoperative in the surgical segment and non-surgical segment ( P>0.05). Pearson correlation analysis showed that the volume of cervical longus and VAS at the 3rd month ( r=-0.308, P<0.05), the 12th month ( r=-0.210, P<0.05) and the last follow-up ( r=-0.404, P<0.05) were negatively correlated; Among the volume of cervical longus and NDI in the 3rd month ( r=-0.511, P<0.05), 12th month ( r=-0.518, P<0.05) and the last follow-up ( r=-0.352, P<0.05), there was a negative correlation; However, there was no statistically significant correlation between the cervical longus muscle volume and mJOA at each follow-up time point ( P>0.05); There was no significant correlation between CESA/VBA and VAS, NDI, and mJOA at the 3rd, 12th and last follow-up ( P>0.05). Conclusion:The volume and morphology of cervical longus after ACDF was significantly reduced compared with that before the operation, but the volume and morphology of the cervical extensor muscle did not change significantly. ACDF surgery mainly affects the cervical longus corresponding to the surgical segment, and the volume is negatively correlated with the VAS and NDI during follow-up.