The relationship between the length of cervical spinous process and affected segment of cervical spondylotic myelopathy / 中华骨科杂志

ABSTRACT

Objective:To explore the relationship between the length of cervical spinous process and cervical motion and affected segment of cervical spondylotic myelopathy(CSM).Methods:Retrospective analysis was performed on 375 patients who underwent cervical surgical treatment due to single-segment cervical spondylotic myelopathy from January 2015 to January 2019. There were 200 males and 175 females, aged 50.72±9.39 (range 40 to 60) years. Several parameters, including the sagittal diameter of vertebral body, the sagittal diameter of cervical canal, the length of cervical spinous process, C 3-C 7 lordotic angle, range of motion (ROM) at C 3-C 7 and segmental ROM were measured via preoperative plain radiographs. All parameters were tested via Shapiro-Wilk method. Pearson correlation analyses was used to quantify the relationship between the lengths of C 3-C 7 spinous process and segmental ROMs. Receiver operating characteristic (ROC) curve was mapped to obtain the cut-off points according to the length of cervical spinous process which had significant differences. Patients were divided into two groups based on the cut-off points. χ2 test and t test were used to exclude the interference of age, gender and other anatomical factors and compare the differences in the affected segment of cervical spondylotic myelopathy between groups, so as to analyze the relationship between the length of cervical spinous process and affected segment of cervical spondylotic myelopathy. Results:There were significant differences of C 6 spinous process 27.82±6.01 mm and significantly negative correlation between the length of C 6 spinous process and the ROM at C 6,7 segment ( r=-0.338, P<0.001), while no significant correlations were found in other segments. ROC curves were mapped to obtain the cut-off points, and the cut-off point was 0.76. Group I: the ratio of the length of spinous process of C 6/C 7 (C 6/C 7 ratio, range 0.49 to 1.01) under 0.76, Group II: C 6/C 7 ratio more than 0.76. Compared with patients with longer-type C 6 spinous process (C 6/C 7 ratio ≥0.76), patients with shorter-type C 6 spinous process (C 6/C 7 ratio <0.76) had significantly bigger ROM at C 6,7 segment (10.11° vs 7.10°, P<0.001) and higher incidence of C 6,7 spinal cord compression ( χ2=16.642, P<0.001, OR=2.521), while differences in age, sex, sagittal diameters of vertebral body and spinal canal between two groups were not significant. Conclusion:The length of C 6 spinous process was significantly correlated with ROM at C 6,7 segment and the incidence of C 6,7 degenerative myelopathy. The length of C 6 spinous process can be considered as a predictor of development of C 6,7 degenerative myelopathy.