Differences in radiological and functional outcomes between cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament after multi-level laminoplasty

Abstract Objective The purpose of this study was to compare the radiological and functional outcomes between patients with cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) after multi-level laminoplasty. Methods This study included 75 patients (32 with CSM and 43 with OPLL) with preserved cervical sagittal balance who underwent multi-level laminoplasty for cervical myelopathy. The radiological outcomes were analyzed using the following parameters: C2–C7 Cobb angle in neutral (C27AN), flexed (C27AF), and extended (C27AE) neck postures; C2–C7 range of motion (C27ROM); T1 slope (T1S); and C2–C7 sagittal vertical axis (C27SVA). The functional outcomes were analyzed using the modified Japanese Orthopedic Association (mJOA) score, Nurick grade, and recovery rate. The radiological and functional outcomes between the two groups were evaluated 12-months postoperatively. Results C27AF, C27ROM, and C27SVA in the CSM group and C27ROM in the OPLL group decreased significantly (p < 0.05). There was a significant difference in ΔC27SVA between the two groups (9.41 ± 17.06 mm vs. 1.10 ± 17.15 mm, p < 0.05). However, there were no significant intra- or intergroup changes and differences in C27AN (p > 0.05). The functional outcomes including mJOA score (p = 0.251), Nurick grade (p = 0.316), and recovery rate (p = 0.435) showed no significant intergroup differences. Conclusions Although there were no significant differences in functional outcomes between the two groups, the CSM group showed a greater deterioration in sagittal balance with an increase of C27SVA than the OPLL group after multi-level laminoplasty.