ASOCIACIÓN DE LA LÍNEA K NEGATIVA EN LOS RESULTADOS FUNCIONALES Y QUIRÚRGICOS DE PACIENTES CON PATOLOGÍA CERVICAL DEGENERATIVA OPERADOS POR ABORDAJE ANTERIOR
Student Thesis:
Student thesis
Thesis
Objective:
To evaluate whether the classification based on K-line (positive or negative) on sagittal MRI is associated with differences in postoperative clinical outcomes in patients with degenerative cervical spine pathology treated via anterior approach.
Methods:
A retrospective comparative study was conducted at a tertiary care center, including patients who underwent anterior surgical approach between 2021 and 2024 at Hospital Clínica Nova. Patients were divided into two groups according to the K-line classification obtained from imaging studies. Sociodemographic, surgical, and clinical variables were compared, including pain progression (Visual Analog Scale, VAS) and functional disability (Neck Disability Index, NDI) at five time points: preoperative, immediate postoperative, 1 month, 3 months, and 6 months. Statistical analysis was performed using independent samples t-test, Mann–Whitney U test, chi-square test, and repeated measures ANOVA.
Results:
A total of 84 patients were included, with a mean age (standard deviation) of 55.8 (10.4) years. The sample consisted of 49 men (58.3%) and 35 women (41.7%). Patients were divided into two groups according to the K-line: 64 patients (76.2%) with a positive K-line and 20 patients (23.8%) with a negative K-line. No statistically significant differences were identified between the groups in terms of age, sex, BMI, comorbidities, number of levels operated, type of implant, intraoperative bleeding, or surgical time. The group with a negative K-line had a higher proportion of patients dedicated to household work (55% vs. 21.9%, p = 0.031).
Both groups showed progressive and sustained improvement on the Visual Analog Scale (VAS) and Neck Disability Index (NDI) throughout follow-up. In VAS, the negative K-line group improved from 6.9 (0.2) preoperatively to 3.9 (0.3) immediately post-op, 2.9 (0.2) at 1 month, 2.3 (0.1) at 3 months, and 1.6
(0.1) at 6 months. The positive K-line group showed 7.0 (0.1) preoperatively, 3.6
(0.1) immediately post-op, 2.6 (0.1) at 1 month, 1.8 (0.08) at 3 months, and 1.3 (0.06) at 6 months. No statistically significant differences were found between the groups (p = 0.104).
In NDI, the negative K-line group evolved from 28.2 (1.1) preoperatively to 6.9 (0.3) immediate post-op, 4.6 (0.2) at 1 month, 3.3 (0.2) at 3 months, and 2.2
(0.1) at 6 months. In comparison, the positive K-line group had 29.5 (0.6)
preoperatively, 6.8 (0.2) immediately post-op, 4.5 (0.1) at 1 month, 3.2 (0.1) at
3 months, and 2.3 (0.1) at 6 months. No statistically significant differences were found between groups (p = 0.339).
Postoperative complications were infrequent (2.4%), and no major adverse events or surgical reinterventions were recorded.
Conclusion:
Anterior cervical spine surgery showed favorable and safe functional outcomes. K-line negativity was not associated with worse clinical outcomes or increased complication rates. These findings support the anterior approach as an effective and safe option even in patients with a negative K-line, provided there is appropriate patient selection and individualized surgical planning.
To evaluate whether the classification based on K-line (positive or negative) on sagittal MRI is associated with differences in postoperative clinical outcomes in patients with degenerative cervical spine pathology treated via anterior approach.
Methods:
A retrospective comparative study was conducted at a tertiary care center, including patients who underwent anterior surgical approach between 2021 and 2024 at Hospital Clínica Nova. Patients were divided into two groups according to the K-line classification obtained from imaging studies. Sociodemographic, surgical, and clinical variables were compared, including pain progression (Visual Analog Scale, VAS) and functional disability (Neck Disability Index, NDI) at five time points: preoperative, immediate postoperative, 1 month, 3 months, and 6 months. Statistical analysis was performed using independent samples t-test, Mann–Whitney U test, chi-square test, and repeated measures ANOVA.
Results:
A total of 84 patients were included, with a mean age (standard deviation) of 55.8 (10.4) years. The sample consisted of 49 men (58.3%) and 35 women (41.7%). Patients were divided into two groups according to the K-line: 64 patients (76.2%) with a positive K-line and 20 patients (23.8%) with a negative K-line. No statistically significant differences were identified between the groups in terms of age, sex, BMI, comorbidities, number of levels operated, type of implant, intraoperative bleeding, or surgical time. The group with a negative K-line had a higher proportion of patients dedicated to household work (55% vs. 21.9%, p = 0.031).
Both groups showed progressive and sustained improvement on the Visual Analog Scale (VAS) and Neck Disability Index (NDI) throughout follow-up. In VAS, the negative K-line group improved from 6.9 (0.2) preoperatively to 3.9 (0.3) immediately post-op, 2.9 (0.2) at 1 month, 2.3 (0.1) at 3 months, and 1.6
(0.1) at 6 months. The positive K-line group showed 7.0 (0.1) preoperatively, 3.6
(0.1) immediately post-op, 2.6 (0.1) at 1 month, 1.8 (0.08) at 3 months, and 1.3 (0.06) at 6 months. No statistically significant differences were found between the groups (p = 0.104).
In NDI, the negative K-line group evolved from 28.2 (1.1) preoperatively to 6.9 (0.3) immediate post-op, 4.6 (0.2) at 1 month, 3.3 (0.2) at 3 months, and 2.2
(0.1) at 6 months. In comparison, the positive K-line group had 29.5 (0.6)
preoperatively, 6.8 (0.2) immediately post-op, 4.5 (0.1) at 1 month, 3.2 (0.1) at
3 months, and 2.3 (0.1) at 6 months. No statistically significant differences were found between groups (p = 0.339).
Postoperative complications were infrequent (2.4%), and no major adverse events or surgical reinterventions were recorded.
Conclusion:
Anterior cervical spine surgery showed favorable and safe functional outcomes. K-line negativity was not associated with worse clinical outcomes or increased complication rates. These findings support the anterior approach as an effective and safe option even in patients with a negative K-line, provided there is appropriate patient selection and individualized surgical planning.