Improvement in cervical lordosis and sagittal alignment after vertebral body sliding osteotomy in patients with cervical spondylotic myelopathy and kyphosis

Abstract

OBJECTIVE Vertebral body sliding osteotomy (VBSO) is a safe, novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. Another advantage of VBSO may be the restoration of cervical lordosis through multilevel anterior cervical discectomy and fusion (ACDF) above and below the osteotomy level. This study aimed to evaluate the improvement and maintenance of cervical lordosis and sagittal alignment after VBSO. METHODS A total of 65 patients were included; 34 patients had undergone VBSO, and 31 had undergone anterior cervical corpectomy and fusion (ACCF). Preoperative, postoperative, and final follow-up radiographs were used to evaluate the improvements in cervical lordosis and sagittal alignment after VBSO. C0-2 lordosis, C2-7 lordosis, segmental lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and Japanese Orthopaedic Association scores were measured. Subgroup analysis was performed between 15 patients with 1-level VBSO and 19 patients with 2-level VBSO. Patients with 1-level VBSO were compared to patients who had undergone 1-level ACCF. RESULTS C0-2 lordosis (41.3 degrees +/- 7.1 degrees), C2-7 lordosis (7.1 degrees +/- 12.8 degrees), segmental lordosis (3.1 degrees +/- 9.2 degrees), and C2-7 SVA (21.5 +/- 11.7 mm) showed significant improvements at the final follow-up (39.3 degrees +/- 7.2 degrees, 13 degrees +/- 9.9 degrees, 15.2 degrees +/- 8.5 degrees, and 18.4 +/- 7.9 mm, respectively) after VBSO (p = 0.049, p < 0.001, p < 0.001, and p = 0.038, respectively). The postoperative segmental lordosis was significantly larger in 2-level VBSO (18.8 degrees +/- 11.6 degrees) than 1-level VBSO (10.3 degrees +/- 5.5 degrees, p = 0.014). The final segmental lordosis was larger in the 1-level VBSO (12.5 degrees +/- 6.2 degrees) than the 1-level ACCF (7.2 degrees +/- 7.6 degrees, p = 0.023). Segmental lordosis increased postoperatively (p < 0.001) and was maintained until the final follow-up (p = 0.062) after VBSO. However, the postoperatively improved segmental lordosis (p < 0.001) decreased at the final follow-up (p = 0.045) after ACCF. CONCLUSIONS Not only C2-7 lordosis and segmental lordosis, but also C0-2 lordosis and C2-7 SVA improved at the final follow-up after VBSO. VBSO improves segmental cervical lordosis markedly through multiple ACDFs above and below the VBSO level, and a preserved vertebral body may provide more structural support.