Outcome of Decompressive Laminectomy with or without Posterior Screw Fixation for Thoracic Ossification of the Ligamentum Flavum with Disc Degeneration

Objective Thoracic myelopathy caused by the ossification of the ligamentum flavum (OLF) is commonly treated with surgical decompression. This study aimed to compare the clinical and radiological outcomes of surgical decompression without posterior screw fixation (decompressive laminectomy [DL] group) and with posterior screw fixation (laminectomy with screw fixation [LSF] group) for thoracic myelopathy due to OLF with disc degeneration. Methods A retrospective review of 35 patients (DL group, n = 19; LSF group, n = 16) was conducted. Clinical variables (Japanese Orthopaedic Association scores) and radiological variables (including sagittal vertical axis, pelvic tilt, thoracic kyphosis, sacral slope, lumbar lordosis (LL), segmental Cobb’s angle, dynamic Cobb’s angle, and dynamic thoracolumbar junction [dTLJ] at the operated level) were measured preoperatively and 1 year postoperatively. Results Both groups exhibited significant improvements in clinical characteristics postoperatively. LL significantly increased at 1 year postoperatively in both groups. Other sagittal alignment parameters did not change significantly. The dTLJ did not differ significantly between the groups preoperatively; however, the dTLJ of the DL group was larger than that of the LSF group at 1 year postoperatively. There was no significant difference between the groups’ dynamic Cobb’s angles or risk of complications. Conclusion Decompression surgery for OLF resulted in clinical improvement regardless of whether posterior fixation was performed. Decompression without posterior fixation could allow thoracolumbar motion preservation and might be an effective approach for thoracic OLF with disc degeneration. Key words: Intervertebral disc degeneration; Laminectomy; Ligamentum flavum; Ossification; heterotopic; Pedicle screws; Range of motion