[Chronological changes in the operative indications and approaches for the treatment of spondylosis deformans of the spine].

Spondylosis deformans of the spine occurs due to degenerative changes of the intervertebral disc, vertebral body and hypertrophy of the interarticular joint. Such changes, including narrowing of the disc space, degeneration of the endplate, spur formation, hypertrophy of the facet joint, spondylolisthesis, abnormal curvature of the spine, are generally observed in the elderly people. Neurological abnormalities may develop because of spinal cord compression or circulation disturbances. In such cases, surgical intervention may be considered. Significant decompression of the spinal cord and root and reconstruction of the load-sharing ability of the spine are the most important purposes of surgical interventions. However, the most appropriate surgical approach for cervical spondylotic myelopathy remains controversial. Previous comparative series tend to favor the anterior surgical approach for patients with cervical spondylotic myelopathy arising from focal or segmental lesions. Surgery via the posterior approaches offers significant advantages for the treatment of patients with multilevel disease. However, laminectomy should be avoided in cases with straightening or reversal of the curvature of the cervical vertebral column. The appropriate surgical approach should be decided after careful consideration of the detailed biomechanical properties of the lesions. Various techniques of decompressive laminoplasty have been developed exclusively in Japan. Clinical evidence regarding the applicability of these methods is inconclusive; however, some significant improvements have been observed after the reconstruction of posterior elements of the spine in some cases. Here, the chronological developments in the surgical procedures used for treating-cervical and lumbar lesions have been briefly described.