Clinical Study Of Hinge Union In Unilateral Open-door Laminoplasty With Neulen Plates

Objective:To evaluate the ability of laminoplasty with Neulen plates to achieve stable laminar arch reconstruction and to determine the bony healing occurs in such constructs postoperatively.Methods:From January2012to December2012,26cases suffering from cervical spinal stenosis underwent unilateral open-door expansive laminoplasty plus Neulen plates fixation. Of these, there were15males and11females, with a mean age of62years (range35-81). Preoperative CT and MRI showed the16patient had multiple segmental disc herniations complicated with hypertrophy of ligamentum flavum and10patients suffered from ossification of posterior longitudinal ligament. All patients with available postoperative computed tomography(CT) scans at1week,3months and6months postoperatively formed the basis of this study. In all cases, Neulen plates and screws worked as the only support and internal fixation after routine unilateral open-door laminoplasty and decompression. In16cases, segmental fixation was performed with a plate at each level; in7cases, plates were placed at all levels except one; in3cases, plates were used at only C3, C5, and C7.Each cortex (dorsal and ventral) was evaluated for the presence of bridging by either cancellous or cortical bone. The overall healing status of the hinge was determined by combining the status of the dorsal and ventral cortices according to the matrix. Both the ventral and dorsal cortices must be bridged with bone to be considered healed. We evaluated the bony healing and complications about Neulen plates.Results:The surgerys were performed smoothly without plate breakage, spinal cord injury and other complications. In operation, breakage of dorsal and ventral cortex occurred in three segments. But the lamina did not present drift and obvious unsteadiness and effectively maintained the location of the lamina after the laminaplasty and internal fixation. There were no nerve damage and other complications. CT scans from117levels of26patients at3months demonstrated that80levels (68.4%) were healed. And of69levels from15patients (10patients with5plates,4patients with4plates and1with3plates) at6months,59levels (85.5%) were healed.Laminoplasty with Neulen plates provided stable reconstruction of an expanded laminar arch with no failures, dislodgements, adverse neurologic consequences, or premature closures in all levels. And three segments that the ventral and dorsal cortices were not bridged did not heal.But they maintained patent expansion of the spinal canal. The canal without plate was patent postoperatively.Conclusion:Neulen plates can provide instant and early support of the expanded canals, promote early hinge union, maintain patent expansion of the spinal canal and prevent "Spring-back" closure.