Effects of two different fixations on hinge bony fusion in unilateral open-door cervical expansive laminoplasty

English Keywords:Unilateral open-door cervical expansive laminoplasty  Centerpiece mini-plate  hinge side  Bony fusion

English Abstract:

  【Abstract】 Objectives: To investigate the effects of two different fixations on the complete fracture and bony fusion of hinge side in unilateral open-door cervical expansive laminoplasty. Methods: 58 patients received the unilateral open-door cervical expansive laminoplasty from September 2009 to March 2011, including 47 males and 11 females, with a mean age of 61(35-81) years. 225 laminae were fixed by Centerpiece mini-plate and 62 laminae were fixed by suture suspension. 56 patients had five laminae opened, 1 patient had 4 laminae and 1 patient had 3 laminae opened. The Japan Orthopedic Association(JOA) score was used to evaluate the pre- and post- operative neurofunction. The fracture severity was evaluated by CT scans one week postoperatively, and all laminae were divided into three subgroups: incomplete fracture, complete fracture with no displacement and complete fracture with displacement. The bony fusion of hinge side was observed and compared between the two fixation methods under CT scans at three and six months postoperatively. Results: There were 124 incomplete fractured laminae, 118 complete fractured laminae with no displacement and 45 complete fractured laminae with displacement. The mean follow-up time was 6-27 months with an average of 16 months. No instrument displacement or broken, no lamina screw back-outs and no lamina re-closure were observed during follow-up. The cervical canal diameters were 9.9±2.4 preoperatively and 17.0±2.9 postoperatively, which showed significant difference. The JOA score showed significant improvement(P<0.001) from 7.7±3.3 preoperatively to 12.7±4.1 postoperatively. The Centerpiece mini-plate method had a higher hinge bony union rate than the other at 3 months after operation(82% vs. 70%, P=0.042), but no significant difference was noted as for the fracture severity(P=0.728) and bony fusion rate at 6months after operation(P=0.141) between two methods. Centerpiece mini-plate method for complete fracture with no displacement had significant higher hinge bony fusion, no matter 3 months(86% vs. 57%, P=0.004) or 6 months(92% vs. 85%, P=0.048) postoperatively. However the incidence for incomplete fracture and complete fracture with no displacement showed no significant. Conclusions: The Centerpiece mini-plate method for unilateral open-door cervical expansive laminoplasty increases the hinge′s stability and promotes the bony fusion of complete fracture with no displacement.