• Kazunari Takeuchi, Toru Yokoyama, Kanichiro Wada, Gentaro Kumagai, Hitoshi Kudo, Sunao Tanaka, Toru Asari, Eiji Sasaki, Kazushige Koyama, Masayuki Ichinohe, and Yasuyuki Ishibashi.
• Department of Orthopedic Surgery, Odate Municipal General Hospital, Odate, Japan.
• Spine. 2021 Oct 1; 46 (19): E1031-E1041.

Study DesignA retrospective comparison of the surgical outcome after cervical laminoplasty for cervical spondylotic myelopathy (CSM) using a modified K-line based on lordosis in neck extension as a predictor: in K-line Back CSM (KB group), the K-line crosses the ventral edge of any of the spinous processes, whereas in K-line Front CSM (KF group), the K-line does not.ObjectiveTo investigate the neurological and radiological outcomes 5 years after surgery and the contact between the spinal cord and posterior elements after laminoplasty for CSM using the modified K-line.Summary Of Background DataNo indicators on a lateral radiograph can predict the neurological outcome after laminoplasty for CSM.MethodsPatients with CSM were divided into KB (n = 20) and KF groups (n = 13). We compared the postoperative Japanese Orthopedic Association (JOA) score, recovery rate, grip-and-release and foot-tapping test results, alignment, and contact between the spinal cord and posterior elements between the two groups.ResultsThe postoperative JOA score and its recovery rate were significantly lower in the KB group (12.4 points and 34.1%, respectively) than in the KF group (14.1 points and 59.0%, respectively) at final follow-up (P = 0.0415 and 0.0458). The grip-and-release and foot-tapping test results improved significantly in the KF group but not in the KB group. In the KB group, a larger lordotic angle in extension at 1 year postoperatively continued until final follow-up. The rate of recovery of the JOA score in patients with contacts at both C4/5 and C5/6 and any contact in the KB group (-1.5% and 31.9%, respectively) were lower (P = 0.0013 and 0.0534, respectively) than those in the KF group (58.6% and 60.7%, respectively).ConclusionThe K-line Back predicts a poor neurological outcome after laminoplasty for CSM. Decompression with fusion may be recommended for these patients.Level of Evidence: 4.Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.

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