Objective To investigate the radiological features of degenerative cervical kyphosis (DCK) and the relationship between cervical sagittal parameters. Methods The quality of life scores and imaging data of 89 patients with DCK treated between February 2019 and February 2022 were retrospectively analysed. There were 47 males and 42 females, with an average age of 48.4 years (range, 25-81 years). Quality of life scores included visual analogue scale (VAS) score and neck disability index (NDI). The imaging data included C0-C2 angle, C2-C7 angle, C3-C7 inclination of zygapophyseal joints, C7 slope (C7S), cervical sagittal vertical axis (cSVA), kyphosis range, and kyphosis focal. The patients were grouped by gender, and the differences of the above parameters between the two groups were compared. Pearson correlation was used to analyze the relationship between age, quality of life scores, and cervical sagittal parameters, and the relationship between cervical sagittal parameters. Results The preoperative VAS score was 0-9 (mean, 4.3); NDI was 16%-44% (mean, 30.0%). There was no significant difference in VAS score and NDI between male and female groups (P>0.05). The kyphosis range of cervical spines was C3-5 in 3 cases, C3-6 in 41 cases, C3-7 in 30 cases, C4-6 in 4 cases, C4-7 in 10 cases, C5-7 in 1 case, and the kyphosis focal was mostly located between C4-C5 (78/89, 87.64%). The C3-C7 inclination of zygapophyseal joints were (60.25±5.56)°, (55.42±5.77)°, (53.03±6.33)°, (58.39±7.27)°, and (64.70±6.40)°, respectively. The C0-C2 angle, C2-C7 angle, C7S, and cSVA were (–23.81±6.74)°, (10.15±2.94)°, (15.31±4.59)°, and (2.37±1.19) mm, respectively. The C7S and cSVA of males were significantly larger than females (P<0.05), with no significant difference in other parameters between male and female groups (P>0.05). VAS score and NDI were negatively correlated with C0-C2 angle (P<0.05), and positively correlated with C2-C7 angle and cSVA (P<0.05); VAS score was negatively correlated with C7S (P<0.05). Except VAS, NDI and all cervical sagittal parameters were affected by age. Age was positively correlated with NDI, C7S, and cSVA (P<0.05), and negatively correlated with C0-C2 angle and C2-C7 angle (P<0.05). The correlation analysis of cervical sagittal parameters showed that C0-C2 angle was negatively correlated with C2-C7 angle and cSVA (P<0.05); C7S was negatively correlated with C2-C7 angle (P<0.05) and positively correlated with cSVA (P<0.05). There was no correlation among other parameters (P>0.05). ConclusionThe inclination of zygapophyseal joints of cervical spines of DCK patients is U-shaped in the kyphosis range, and the inclination at the kyphosis focal is the smallest. When cervical degenerative kyphosis occurs, in addition to the interaction of sagittal parameters, age, gender, neck pain, and dysfunction will also affect the cervical sagittal balance. Furthermore, cervical curvature and morphological changes are not purely local problems.
Objective To investigate the imaging characteristics of cervical kyphosis and spinal cord compression in cervical spondylotic myelopathy (CSM) with cervical kyphosis and the influence on effectiveness. Methods The clinical data of 36 patients with single-segment CSM with cervical kyphosis who were admitted between January 2020 and December 2022 and met the selection criteria were retrospectively analyzed. The patients were divided into 3 groups according to the positional relationship between the kyphosis focal on cervical spine X-ray film and the spinal cord compression point on MRI: the same group (group A, 20 cases, both points were in the same position), the adjacent group (group B, 10 cases, both points were located adjacent to each other), and the separated group (group C, 6 cases, both points were located >1 vertebra away from each other). There was no significant difference between groups (P>0.05) in baseline data such as gender, age, body mass index, lesion segment, disease duration, and preoperative C2-7 angle, C2-7 sagittal vertical axis (C2-7 SVA), C7 slope (C7S), kyphotic Cobb angle, fusion segment height, and Japanese Orthopedic Association (JOA) score. The patients underwent single-segment anterior cervical discectomy with fusion (ACDF). The occurrence of postoperative complications was recorded; preoperatively and at last follow-up, the patients’ neurological function was evaluated using the JOA score, and the sagittal parameters (C2-7 angle, C2-7 SVA, C7S, kyphotic Cobb angle, and height of the fused segments) were measured on cervical spine X-ray films and MRI and the correction rate of the cervical kyphosis was calculated; the correlation between changes in cervical sagittal parameters before and after operation and the JOA score improvement rate was analyzed using Pearson correlation analysis. Results In 36 patients, only 1 case of dysphagia occurred in group A, and the dysphagia symptoms disappeared at 3 days after operation, and the remaining patients had no surgery-related complications during the hospitalization. All patients were followed up 12-42 months, with a mean of 20.1 months; the difference in follow-up time between the groups was not significant (P>0.05). At last follow-up, all the imaging indicators and JOA scores of patients in the 3 groups were significantly improved when compared with preoperative ones (P<0.05). The correction rate of cervical kyphosis in group A was significantly better than that in group C, and the improvement rate of JOA score was significantly better than that in groups B and C, all showing significant differences (P<0.05), and there was no significant difference between the other groups (P>0.05). The correlation analysis showed that the improvement rate of JOA score was negatively correlated with C2-7 angle and kyphotic Cobb angle at last follow-up (r=−0.424, P=0.010; r=−0.573, P<0.001), and positively correlated with the C7S and correction rate of cervical kyphosis at last follow-up (r=0.336, P=0.045; r=0.587, P<0.001), and no correlation with the remaining indicators (P>0.05). Conclusion There are three main positional relationships between the cervical kyphosis focal and the spinal cord compression point on imaging, and they have different impacts on the effectiveness and sagittal parameters after ACDF, and those with the same position cervical kyphosis focal and spinal cord compression point have the best improvement in effectiveness and sagittal parameters.