Double-Door Laminoplasty by Splitting Spinous Processes

Abstract

Until the 1970s, laminectomy had been the sole therapeutic option for posterior decompression of the spinal cord. However, wide laminectomy of the cervical spine sometimes caused early and/or late neurological deterioration. The possible causes of such deterioration were the progression of malalignments such as kyphosis or listhesis, postoperative progression of ossification of the posterior longitudinal ligament (OPLL) associated with malalignment and instability of the cervical spine in cases with OPLL, and massive scar formation in the epidural space, known as “postlaminectomy membrane” [1-4]. To resolve the problems associated with laminectomy, several variations of laminoplasty have been developed in Japan [5-7]. Double-door laminoplasty was developed by Kurokawa et al., and a preliminary report was published in 1982 [8]. The main aim of this laminoplasty was to expand the spinal canal symmetrically while preserving the mobility of the cervical spine. In common with other kinds of laminoplasty, the aims of this procedure to preserve the posterior structure in the midline of the cervical spine were to prevent postoperative progression of malalignment and instability of the cervical spine, and to protect the spinal cord from postlaminectomy membrane. In addition, one potential advantage of this procedure was that it preserved the long spinous processes as posterior stabilizers of the neck [8]. Compared with Hattori’s Z-laminoplasty, double-door laminoplasty is technically straightforward. Compared with unilateral hinge-type laminoplasty, such as Hirabayashi’s method, double-door laminoplasty has some theoretical and practical advantages: symmetrical expansion of the spinal canal, avoidance of hemorrhage from the epidural veins because of the limited number of these veins in the midline, and the potential for posterior fusion with a bone graft bridge between the spinous processes.