The Severity of Cervical Disc Degeneration does not Impact Two-year Postoperative Outcomes in Patients with Cervical Spondylotic Myelopathy who Underwent Laminoplasty.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the impact of cervical disc degeneration (CDD) severity on 2-year postoperative outcomes following laminoplasty. SUMMARY OF BACKGROUND DATA: The impact of CDD on postoperative outcomes of cervical laminoplasty has not been well established. METHODS: A total of 144 patients who underwent open-door laminoplasty for cervical spondylotic myelopathy (CSM) were enrolled. Six cervical discs were independently analyzed for degeneration severity using a previously reported grading system (grade 0: none, grade 3: severest). The relationship between the segmental range of motion (ROM) and the severity of CDD was evaluated. Subsequently, after dividing overall patients into mild and severe CDD groups by the average of CDD scores, the mixed-effect model was applied to assess 2-year postoperative outcomes, including physician-assessed myelopathy scores, patient-reported outcomes, and preoperative radiographic parameters. Finally, as additional analysis, the severe CDD group was further divided into two groups: group 1 included patients with a grade 3 CDD change in their most stenotic level and group 2 included the others. The 2-year postoperative myelopathy score was compared between groups 1 and 2. RESULTS: The cervical segments with grade 3 CDD showed significantly smaller ROM compared with those with grade 0, 1, or 2 CDD (p < 0.01). There were no significant differences in postoperative improvements in myelopathy, pain, patient-reported physical and mental status, and radiographic parameters, except for quality of life (QOL) scores between CDD groups. A significant (p = 0.02) postoperative improvement in QOL scores was noted in the severe CDD group. In an additional analysis, myelopathy score at 2 years postoperatively was significantly higher in group 1 than group 2 (p = 0.041). CONCLUSIONS: The severity of CDD did not negatively impact 2-year postoperative laminoplasty outcomes. The postulated reason is that the decreased segmental instability in the level with severe CDD may affect surgical outcomes positively. LEVEL OF EVIDENCE: 3.