Cervical Spine Balance of Multilevel Total Disc Replacement, Hybrid Surgery, and Anterior Cervical Discectomy and Fusion With A Long-term Follow-up

Study Design. Comparative study. Objective. The aim of this study was to compare cervical alignment among three-level total disc replacement (TDR), two prosthesis with one cage (2D1C), one prosthesis with two cages (1D2C), and anterior cervical discectomy and fusion (ACDF), then identify the importance of cervical balance of cervical spondylotic myelopathy (CSM). Summary of Background Data. There were few long-term comparisons on cervical alignment and cervical balance among three-level TDR, 2D1C, 1D2C, and ACDF for CSM. Methods. Twenty-eight patients with TDR, 15 with 2D1C, 36 with 1D2C, and 32 cases with ACDF were included with a mean follow-up of 90.9 +/- 8.9 months. C2-C7 cervical lordosis (CL), C2-C7 sagittal vertical axis (SVA), T1 slope (T1S) were measured on x-ray at preoperation, immediate postoperation, and final follow-up, as well as range of motion (ROM), upper/lower adjacent ROM (UROM/LROM), and adjacent segment degeneration (ASD); cervical balance was assessed by T1S minus CL (T1SCL; 20 degrees). Clinical outcomes included neck disability index (NDI) and Japanese Orthopedic Association (JOA) score. Results. NDI and JOA improved (P < 0.01) at postoperation and final-visit with no difference among four groups. ROM decreased mostly in ACDF group, although with a comparable inter-group UROM/LROM and ASD. All groups gained equal CL-improvement at final-visit. SVA and T1S together with their change were of no differences among groups (P > 0.05). There was a correlation among alignment parameters and between CL and ROM. The inter-group capacity of balance maintaining and imbalance correction was comparable (P > 0.05). The change of T1SCL was not correlated to NDI and JOA (P > 0.05). Conclusion. Adjacent segments were seldom affected. Cervical alignment was equivalently rebuilt among TDR, 2D1C, 1D2C, and ACDF. It was not essential to pay excessive attention to balance.