Comparison of Vertex rod-screw system and Centerpiece plate-screw system in cervical expansive open-door laminoplasty for multilevel cervical spondylotic myelopathy

English Keywords:Cervical spondylotic myelopathy  Expansive open-door laminoplasty  Rod-screw system  Plate-screw system

English Abstract:

  【Abstract】 Objectives: To investigate the clinical outcomes of Vertex rod-screw system and Centerpiece plate-screw system in cervical expansive open-door laminoplasty for multilevel cervical spondylotic myelopathy.Methods: From May 2008 to August 2012, 36 patients with multilevel cervical spondylotic myelopathy were treated with open-door laminoplasty by lower cervical spinous process laminar screw combined with either lateral mass screw Vertex rod-screw system or Centerpiece plate-screw system randomly. 16 patients undergoing expansive open-door laminoplasty by lower cervical spinous process laminar screw combined with lateral mass screw Vertex rod-screw system were included as group A, while 20 patients undergoing expansive open-door laminoplasty by Centerpiece plate-screw system as group B. The operation time, blood loss, preoperative and postoperative JOA scores, neck and shoulder VAS scores and postoperative C5 nerve palsy were recorded. The cervical curvature angle(α) was defined as the cross angle between posterior vertebral body margins of C2 and C7 on cervical radiographs. The cervical range of motion according to the difference of the angle of α between hyperextension and hyperflexion was calculated. The angle of the opened laminae(β) was measured on CT scan at final follow-up. There were no significant differences with regard to preoperative demographic data between two groups(P>0.05). Results: There were no significant differences with regard to operation time and blood loss between two groups(P>0.05). Skin incisions healed well in all patients. There was no neurovascular injury when placing the implants, and no postoperative wound infection, cerebrospinal fluid leakage or other complication was noted. Follow-up time ranged 11-23 months(average 18.5±2.7 months) in group A and 10-22 months(average 17.9±3.2 months) in group B, there was no significant difference between two groups in follow-up time(P>0.05). The improve rate of JOA scores was (55.78±1.23)% in group A and (54.25±1.48)% in group B at final follow-up, which showed no significant difference between two groups(P>0.05). The increased VAS score was 1.10±0.31 in group A and 1.20±0.27 in group B after opertation, which showed no significant differences between two groups(P>0.05). The VAS score was 2.13±0.16 at final follow-up and 3.23±1.28 at preoperation in group A, which showed significant difference(P<0.05). The VAS score was 2.07±0.21 at final follow-up and 3.35±1.15 at preoperation in group B, which showed significant difference(P<0.05). 1 case suffered from severe axial symptoms in each group, 2 cases in group B were noted C5 palsy, all relieved after treatment. The cervical curvature angle was preoperative(16.5°±4.1°) and postoperative(16.3°±5.7°) in group A, and preoperative(15.8°±5.2°) and postoperative(15.6°±6.6°) in group B, which showed no significant differences between preoperative and postoperative cervical curvature angle in both groups(P>0.05). The angle of the opened laminae was 45.6°±3.6° in group A and 48.4°±5.4° in group B at final follow-up, which showed significant difference(P<0.05). The decreased range of motion was 5.78°±4.35° in group A and 5.91°±3.16° in group B at final follow-up, which showed no significant difference(P>0.05). Conclusions: Both Vertex rod-screw system and Centerpiece plate-screw system are effective in cervical expansive open-door laminoplasty for multilevel cervical spondylotic myelopathy, but the former can decrease the incidence of postoperative C5 nerve palsy.