Effect of posterior cervical expansive open-door laminoplasty on cervical sagittal balance

Purpose Posterior cervical expansive open-door laminoplasty (LAMP) is a mature surgical procedure for the treatment of cervical spondylotic myelopathy (CSM), but there are few studies on the changes in cervical sagittal balance. This study aimed to analyze the imaging and clinical data of patients who underwent LAMP and to explore the effect of this procedure on the cervical sagittal balance. Methods This was a retrospective study of the patients who underwent LAMP between 01/2014 and 12/2017. TheC0-C2 Cobb angle, sagittal vertical angle (SVA),C2-C7 Cobb angle, andT1-slope were measured. The Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), and visual analog scale (VAS) were used. Results There were 69 males and 39 females. The mean age was 61.3 +/- 5.3 years. TheC0-C2 Cobb angle increased from 11.3 +/- 5.5 degrees to 26.8 +/- 4.8 degrees (P = 0.186). TheC2-C7 Cobb angle decreased from 13.9 +/- 8.6 degrees to 10.65 +/- 10.7 degrees P = 0.016). SVA increased from 21.0 +/- 5.8 mm to 25.4 +/- 11.5 mm (P = 0.001). The preoperative average JOA score was 11.1 +/- 2.2 points, and the postoperative score was 14.0 +/- 2.1 points, with an average improvement rate of JOA of 46.5 +/- 3.8%. The NDI score decreased from preoperative 15.6 +/- 5.4 points to 11.3 +/- 7.9 points, and the VAS score was decreased from 4.6 +/- 1.8 points to 3.3 +/- 1.6 points (allP < 0.05). Conclusion LAMP improved the neurological function and quality of life of patients with CSM. The cervical vertebrae show a tendency of tilting forward, suggesting that overextension of the upper cervical vertebra might be used to maintain the center of gravity of the skull and horizontal vision.