Cervical sagittal parameters in degenerative cervical spondylolisthesis versus degenerative cervical kyphosis with myeloradiculopathy treated by anterior cervical discectomy and fusion.

BACKGROUND: Adult spinal deformity, especially sagittal imbalance, is affecting health-related quality-of-life (HRQOL) scores. There is a lack of emphasis in the comparison of cervical sagittal parameters in patients with degenerative cervical spondylolisthesis and degenerative cervical kyphosis. The aim of study is to determine the preoperative and postoperative cervical sagittal parameters in myeloradiculopathic patients with degenerative cervical spondylolisthesis and degenerative cervical kyphosis treated by anterior cervical discectomy and fusion (ACDF).

METHODS: A retrospective medical records and radiographic study of 30 adult patients were reviewed. Fifteen patients with degenerative cervical spondylolisthesis and 15 patients with degenerative cervical kyphosis have been performed ACDF from 2010-2020. We measured the preoperative and postoperative cervical sagittal parameters: C0-C2 angle, C1-C2 angle, C2-C7 angle, C2-C7 sagittal vertical axis (SVA), T1 slope, neck tilt angle and thoracic inlet angle. Minimum follow-up period was at least 2 years.

RESULTS: Patients in degenerative cervical kyphosis group have C2-C7 angle less than degenerative cervical spondylolisthesis group (-14.88±7.32 vs. 9.60±13.60), leading to increase the mismatch between T1 slope and C2-C7 angle in kyphotic group and hyperlordosis of C0-C2 angle and C1-C2 angle (31.13±7.68, 37.88±5.08) compare with spondylolisthesis group (13±10.20, 24.60±10.70). Whereas patients with degenerative cervical spondylolisthesis have C2-C7 SVA (33.22±13.92) more than kyphosis group (13.70±13.60). After surgery, there is significant increase of the C2-C7 angle in the kyphosis group compare before and after surgery (-14.88±7.32 vs. 4.10±11.80). While the spondylolisthesis group has no significantly different parameters compare to before surgery. However, the postoperative cervical sagittal parameters of all patients are within the normal thresholds (T1-Slope minus C2-C7 lordosis <15° and C2-C7 SVA <40 mm).

CONCLUSIONS: The study demonstrates the difference of sagittal parameters between degenerative cervical spondylolisthesis and kyphosis before and after surgery. ACDF not only provides neural decompressive procedure, but also corrects the regional cervical sagittal parameters.