Laminoplasty after Anterior Spinal Fusion for Cervical Spondylotic Myelopathy

Abstract

Purpose. To review outcomes of laminoplasty after anterior spinal fusion (ASF) in 8 patients with cervical spondylotic myelopathy (CSM). Methods. Records of 3 men and 5 women aged 49 to 80 (mean, 60) years who underwent laminoplasty after ASF for CSM were reviewed. Before and after ASF and laminoplasty, the causes of CSM, mechanical instability, the Pavlov Torg ratio, the numbers of levels of stenosis, myelomalacia, ASF, and laminoplasty, the modified Japanese Orthopaedic Association (JOA) score, and the Hirabayashi recovery rate were recorded in all the patients. Results. After ASF, the mean modified JOA score improved to 9.6 from 8.3 (p=0.05), with a mean Hirabayashi recovery rate of 12.5% at the 12-month follow-up. However, it deteriorated to 9 after a mean of 25 (range, 3–54) months follow-up. Indications for a secondary laminoplasty included inadequate decompression (n=5), progression of prolapsed discs (n=4), osteophytes (n=3), ossification of the posterior longitudinal ligament (n=1), and hypertrophy of the ligamentum flavum (n=4). The mean interval between ASF and laminoplasty was 30 (range, 14–55) months. The mean number of levels of laminoplasty was 4.5 (range, 4–5). After laminoplasty, all patients had adequate spinal decompression with no cord compromise, neck pain or stiffness, despite the signal change remaining the same. Two patients improved, 2 deteriorated, and 4 remained unchanged with respect to walking status. The mean modified JOA scores improved to 9.7 from 9 (p=0.38); the mean Hirabayashi recovery rate was −1.5%. All patients had persistent myelomalacia, which was not reflected in the improved modified JOA score. Conclusions. Initial surgery (such as ASF) is more effective in relieving cord compromise and myelopathy. Inadequate decompression and progression of disease may necessitate secondary laminoplasty, which conferred additional benefits that 5 of our 8 patients enjoyed despite persistence of myelomalacia.