Expansive open-door laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine: Surgical indications, technique, and outcomes

Introduction In 1968, Kirita devised a sophisticated extensive laminectomy technique in which the laminae were thinned and divided at the midline by a high-speed drill followed by en bloc resection of the laminae to achieve decompression of the spinal cord safely in patients with cervical spondylosis and ossification of the posterior longitudinal ligament (OPLL) [1]. This technique added much safety to conventional laminectomy and signifi - cantly reduced the rate of neurological complications. Hirabayashi et al. simplifi ed Kirita's method, in which the bilateral bony gutters at the junction of the laminae and the facet joints were made using a high-speed drill followed by en bloc removal of the laminae [2]. The idea of open-door laminoplasty evolved when they noticed dural pulsation when one side of the laminae was lifted before their total removal. They performed the fi rst case using this technique in 1977, leaving the ventral cortex on one side as a hinge and lifting the lamina on the other side, just like opening a book cover; they named it "expansive open-door laminoplasty (ELAP)" [3,4]. The advent of ELAP has contributed signifi cantly to the establishment of the concept "laminoplasty," which later became the treatment of choice for cervical myelopathy in Japan and has also led to the development of various technical modifi cations. Laminoplasty has become the treatment of choice for cervical myelopathy, and satisfactory results have been reported [2,5-7]. Although ELAP is not radical decompression surgery that directly removes the ossifi ed ligament, it has a total decompression effect induced by the dorsal shift of the spinal cord in addition to local decompression of the spinal cord by posterior displacement of the laminae (Fig. 1) [8]. Several studies have proven that the decompression effect of ELAP is virtually equivalent to that of laminectomy and anterior corpectomy and fusion [9]. The posterior structures, including the lamina and the supraspinous and interspinous ligaments, are preserved; and the cervical muscles are reattached to reconstruct the spinal canal, thereby maintaining the preoperative cervical alignments and at the same time restoring cervical stability. Herkowitz concluded from his biomechanical study that the stability of the cervical spine after ELAP was not signifi cantly different from that of the intact spine [10]. Indeed, kyphotic deformity or instability after ELAP that required salvage surgery has rarely been experienced in our institution [6,11]. Moreover, the incidence of adjacent-segment disease, which may also lead to a salvage operation, was much lower after ELAP than after anterior decompression and fusion [2].