Cervical laminoplasty is an effective and established technique for treating multilevel spondylotic myelopathy or ossification of the posterior longitudinal ligament. However, because laminoplasty was aimed at preserving only the bony structures of posterior cervical elements, kyphotic deformity or instability sometimes occurs during the follow-up period, and either one of these can result in a poor long-term outcome. The purpose of this report is to study the effectiveness of preserving the tension band, particularly the nuchal ligament, in performing midline splitting expansive laminoplasty. Since 1998, we have performed midline splitting expansive laminoplasty on 22 patients with multilevel spondylotic myelopathy or ossification of the posterior longitudinal ligament. The patients were divided into two groups : for the patients in Group 1 (12 cases), we used the ordinary posterior midline approach; for the patients in Group 2 (10 cases), we used the posterior approach, preserving the nuchal ligament. The mean age of the patients and the average follow-up period were 55.42 years and 288.6 days, respectively, in Group 1, and 59.25 years and 207.5 days in Group 2. Each patient's clinical course was assessed according to the neurosurgical cervical spine scale (NCSS). We calculated the cervical curvature index according to Ishihara's method, the cervical range of motion, and the cross-sectional area of the nuchal muscles. The patients in both groups showed improvement in NCSS. The cervical curvature index decreased over time in group 1. However, in group 2, cervical curvature did not significantly decrease. The cross-sectional area of the nuchal muscles decreased in both groups. There was no correlation between the curvature index and the cross-sectional area. The nuchal ligament plays an important role in maintaining lordosis of the cervical spine after an expanding laminoplasty. However, because the follow-up periods in this study were short, further study of long-term follow-up is needed.
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