[Effectiveness analysis of Vertex rod-screw system in cervical expansive open-door laminoplasty]

To evaluate the clinical application value and short-term results of Vertex rod-screw system in cervical expansive open-door laminoplasty.

Between February 2008 and January 2010, 28 patients underwent Vertex rod-screw system fixation in cervical expansive open-door laminoplasty, including 15 cases of cervical spondylotic myelopathy, 5 cases of ossification of posterior longitudinal ligament, and 8 cases of cervical spondylosis with spinal stenosis. There were 16 males and 12 females, aged 42-77 years (mean, 61.3 years). The disease duration was 2 months to 11 years. The decompression range of cervical spine was from C3 to C7. The operation time, blood loss, Japanese Orthopedic Association (JOA) scores, and incidence of axial symptom were recorded. Pre- and postoperative curvature angles were demonstrated by the cross angle between posterior vertebral body margins of C2 and C7 on cervical X-ray films. The angle of the opened laminae was measured on CT scan at last follow-up.

The operation time was (142.5 +/- 22.8) minutes, and the blood loss was (288.2 +/- 55.1) mL. All incisions healed by first intention. All patients were followed up 14-25 months (mean, 22 months). CT showed that no reclosed open-laminae or loosening and breakage of rod-screw system occurred at 1 week and 1 year after operation. The axial bony fusion rate was 89.3% (25/28). The improvement rate of JOA scores at 1 week after operation (29.5% +/- 15.0%) was significantly smaller than that at 1 year after operation (64.9% +/- 28.1%) (t = 0.810, P = 0.000). No case presented with C5 nerve root palsy. The cervical curvature angle was (24.29 +/- 5.04) degrees before operation, was (23.89 +/- 3.57) degrees at 1 week, and was (23.41 +/- 3.35) degrees at 1 year after operation, showing no significant difference between pre- and postoperative angles (P > 0.05). The angle of the opened laminae was (27.90 +/- 4.74) degrees at 1 week after operation, and was (28.07 +/- 4.21) degrees at 1 year after operation, showing no significant difference (P > 0.05).

Vertex rod-screw system in cervical expansive open-door laminoplasty is effective in preventing reclosed open-laminae, which can reduce the loss of cervical curvature angle.