[Clinical studies on the significance of en bloc laminoplasty for cervical compressive myelopathy].

The aim of this study was clinical evaluation of en bloc laminoplasty for compressive myelopathy. Subjects were 55 patients with severe myelopathy due to ossification of posterior longitudinal ligament or spinal canal stenosis in the cervical spine. The average age at surgery was 58 years old and average follow-up period 25 months. Stable expansion of the spinal canal was shown and the average extent of the canal enlargement in sagittal diameter was 4.8 +/- 1.8 mm roentgenologically. Symmetrical expansion of the canal, good bony fusion and remodelling of the posterior elements of the spine were observed in CT. No marked malalignment or instability of the cervical spine were found, but limitation of flexion-extension movement was noticed. Neurological recovery was remarkable; 44 patients were rated as excellent or good by Robinson's criteria. The average recovery rate was 76.4 +/- 20.1% according to the evaluation system of Japanese Orthopaedic Association (JOA). En-bloc laminoplasty can accomplish a stable expansion of the canal with adequate decompression of the spinal cord.