Abstract: BACKGROUND: Cervical spondylotic myelopathy is induced by the degeneration of the intervertebral junction structure of the cervical spine. The sequence parameters of the sagittal plane of the cervical spine can directly reflect the degeneration of cervical spondylotic myelopathy, which may provide reference for clinical evaluation of the condition and treatment effect.  
OBJECTIVE: To explore the correlation of the changes of cervical sagittal plane sequence parameters and pain degree and cervical function in patients with cervical spondylotic myelopathy, and to analyze its value in clinical efficacy evaluation.
METHODS:  From January 2019 to January 2020, 80 cervical spondylotic myelopathy patients in Affiliated Hospital of Chengde Medical College were selected as the trial group, and 80 asymptomatic adult volunteers during the same period were selected as the control group according to the 1∶1 principle. The parameters of the cervical spine sagittal plane sequence [C2-7 Cobb's angle, T1 tilt angle, cervical sagittal axial distance, ratio of C2-7 Cobb’s angle to T1 tilt angle (C2-7/T1)] were compared between the two groups. The relationship between the parameters of the cervical spine sagittal plane sequence and the occurrence of cervical spondylotic myelopathy was analyzed. After follow up for 6 months, according to the Japanese Orthopaedic Association score, they were divided into excellent group (Japanese Orthopaedic Association score improvement rate ≥ 50%) and non-excellent group (Japanese Orthopaedic Association score improvement rate < 50%). The clinical data of patients with different curative effects, the pain (visual analogue scale) score before and after the operation, the Japanese Orthopaedic Association score, and the changes in the parameters of the cervical sagittal plane sequence were compared. The correlation between the cervical spine sagittal sequence parameters and visual analogue scale, Japanese Orthopaedic Association scores and curative effect was analyzed, and the receiver operating characteristic curve was used to evaluate the evaluation value of each parameter to curative effect.  
RESULTS AND CONCLUSION: (1) The C2-7 Cobb’s angle and C2-7/T1 of the trial group were smaller than those of the control group. T1 tilt angle and cervical sagittal axial distance were greater in the trial group than those of the control group (P < 0.05). C2-7 Cobb’s angle, T1 tilt angle, cervical sagittal axial distance, and C2-7/T1 were significantly correlated with the occurrence of cervical spondylotic myelopathy (P < 0.05). (2) The comparison of the compression segment, operation method, visual analogue scale and Japanese Orthopaedic Association scores before operation, 1 and 6 months after operation of patients in the excellent and non-excellent groups showed statistically significant differences (P < 0.05). (3) The C2-7 Cobb’s angle and C2-7/T1 of the excellent group before operation, 1 and 6 months after the operation were greater than those of the non-excellent group. T1 tilt angle and cervical sagittal axial distance were lower in the excellent group than those of the non-excellent group (P < 0.05). (4) Visual analogue scale score was positively correlated with T1 tilt angle and cervical sagittal axial distance before operation, 1 and 6 months after operation, and negatively correlated with C2-7 Cobb’s angle and C2-7/T1. Japanese Orthopaedic Association score was positively correlated with C2-7 Cobb’s angle and C2-7/T1 before operation, 1 and 6 months after operation, and negatively correlated with T1 tilt angle and cervical sagittal axial distance (P < 0.05). (5) After controlling for other factors such as compression segment and operation method, C2-7 Cobb’s angle, T1 tilt angle, cervical sagittal axial distance, and C2-7/T1 before operation, 1 and 6 months after operation were still significantly related to the curative effect (P < 0.05). (6) The area under curve value of the combined predictive efficacy of cervical spine sagittal sequence parameters at 6 months after surgery was 0.872, which was greater than that of any parameter alone. (7) It is suggested that the sequence parameters of cervical sagittal plane are closely related to the visual analogue scale and Japanese Orthopaedic Association scores of cervical spondylotic myelopathy patients. They are independent factors that affect the surgical results of such patients. The combined examination can provide references for early clinical evaluation of surgical results and improvement of surgical plans.

Key words: cervical spondylotic myelopathy, pain, cervical spine function, axial distance of the cervical spine sagittal plane, T1 tilt angle, receiver operating characteristic curve