Expansive Laminoplasty for Myelopathy in Ossification of the Longitudinal Ligament

Abstract

Laminectomy, which had long been used for treatment of cervical spondylotic myelopathy, including ossification of the longitudinal ligament in the cervical spine, had numerous complications such as postoperative malalignment of the cervical spine and vulnerability of the spinal cord caused by total removal of the posterior structures. In 1977 Hirabayashi devised an open door expansive laminoplasty, which is a relatively easier and safer procedure than laminectomy, that eliminated such problems by preserving the posterior elements. The decompression effect of the expansive laminoplasty against a compressed spinal cord is comparable with that of laminectomy and anterior decompression followed by fusion, whereas the expansive laminoplasty has no structural problems and adverse effects on adjacent disc levels that often are associated with anterior decompression followed by fusion. Average recovery rate of expansive laminoplasty for cervical spondylotic myelopathy has been reported to be approximately 60% (Japanese Orthopaedic Association score) and with long term stability. At present, authors consider all patients with cervical spondylotic myelopathy candidates for expansive laminoplasty except for those having preoperative kyphosis and single level lesion without canal stenosis. Two remaining problems of expansive laminoplasty to be solved are prevention of C5, C6 radicular pain and/or paresis, the most frequent complication that occurs in approximately 5% to 10% of the patients, although most complications resolve spontaneously within 2 years, and correction of nonlordotic alignment to lordosis which are essential for posterior decompression effect of expansive laminoplasty by allowing the spinal cord to shift dorsally.