Abstract:

Objective To observe the changes of sagittal plane balances of cervical spine of the patients underwent posterior cervical single open-door expansive laminoplasty， and to provide the imaging evidence for the postoperative rehabilitation training of the patients. Methods A total of 32 patients who underwent posterior cervical single open-door expansive laminoplasty were selected. According to the median value（15.75 mm ）of sagittal vertical axis （SVA） distance before operation， the patients were divided into low SVA group and high SVA group，and there were 16 patients in each group. The imaging and clinical data of the patients in two groups before operation and at the last follow-up were retrospectively analyzed. The SVA value， cervical lordosis angle （Cobb angle）， and T1 tilt angle （T1s） of the patients at the X-ray lateral view of the cervical spine were detected before operation and at the last follow-up. The postoperative Japanese Orthopaedic Association （JOA） score， neck disability index （NDI） store，and satisfaction score of the patients in two groups were analyzed. Results Compared with before operation， the NDI score of the patients in high SVA group after operation was decreased （P<0.01）， the JOA score was increased （P<0.01）. Compared with before operation， the NDI score of the patients in low SVA group was decreased （P<0.01）， the JOA score was increased （P<0.01）， and the SVA value was increased （P<0.01）， while there were no significant differences in the Cobb angle and T1s （P>0.05）. There was no statistically significant difference in the occurrence of axial symptoms of the patients between low SVA group and high SVA group（P>0.05）. Conclusion In the follow-up of at least 2 years after operation， posterior cervical single open-door expansive laminoplasty has the certain effect on the sagittal plane balance of cervical spine of the patients. The main manifestations are tendency of cervical lordosis and anterior shift of the center of gravity， but the overall stability can still be maintained. The patients with high SVA have a higher incidence of axial symptoms after operation.

Key words: Posterior cervical spine, Single open-door, Spinal canal decompression, Cervical spondylotic myelopathy, Sagittal plane, Centerpiece titanium plate