Sagittal Alignment After Laminectomy Without Fusion as Treatment for Cervical Spondylotic Myelopathy: Follow-up of Minimum 4 Years Postoperatively

Global Spine J. 2020 Jun;10(4):425-432. doi: 10.1177/2192568219858302. Epub 2019 Jun 26.

Abstract

Objectives: The aims of this study were to evaluate the incidence of sagittal malalignment including kyphosis following cervical laminectomy without fusion as treatment for cervical spondylotic myelopathy and to assess any correlation between malalignment and clinical outcome.

Study design: Retrospective cohort study.

Methods: In all, 60 patients were followed up with conventional radiography at an average of 8 years postoperatively. The cervical lordosis (C2-C7 Cobb angle), C2-C7 sagittal vertical axis (cSVA) and C7 slope were measured on both preoperative and postoperative images. Patients completed a questionnaire covering Neck Disability Index (NDI), visual analogue scale for neck pain, and general health (EQ-5D).

Results: Mean C2-C7 Cobb angle was 8.6° (SD 9.0) preoperatively, 3.4° (10.7) postoperatively and 9.6° (14.5) at follow-up. Ultimately, 3 patients showed >20° cervical kyphosis. Mean cSVA was 16.3 mm (SD 10.2) preoperatively, 20.6 mm (11.8) postoperatively, and 31.6 mm (11.8) at follow-up. Mean C7 slope was 20.4° (SD 8.9) preoperatively, 18.4° (9.4) postoperatively, and 32.6° (10.2) at follow-up. The preoperative to follow-up increase in cSVA and C7 slope was statistically significant (both P < .0001), but not for cervical lordosis. The preoperative to follow-up change in cSVA correlated moderately with preoperative cSVA (r = 0.43, P = .002), as did the corresponding findings regarding C7 slope (r = 0.52, P = .0001). A comparison of radiographic measurements with clinical outcome showed no strong correlations.

Conclusions: No preoperative to follow-up change in cervical lordosis was found in this group; 5.0% developed >20° kyphosis. No clear correlation between sagittal alignment and clinical outcome was shown.

Keywords: C7 slope; cervical spondylosis; cervical spondylotic myelopathy; cervical vertebrae; kyphosis; laminectomy; lordosis; myelopathy; sagittal alignment; sagittal vertical axis.