Impact of preoperative cervical sagittal alignment for cervical myelopathy caused by ossification of the posterior longitudinal ligament on surgical treatment

Background: Surgical procedures for cervical myelopathy caused by ossification of the posterior longi-tudinal ligament (OPLL) are often chosen based on OPLL size and cervical spine alignment. Recently, cervical sagittal alignment based on sagittal vertical axis (SVA) has received increased attention as an important determinant of radiological and clinical outcomes after surgery. This study aimed to investi-gate the impact of SVA-based cervical sagittal alignment on surgical treatment for cervical OPLL by reviewing a previous retrospective cohort in which its concept was not taken into account in the surgical procedure choices. Methods: We reviewed a total of 96 consecutive patients who underwent surgery for cervical myelop-athy caused by OPLL from 2008 to 2014. We performed anterior decompression with fusion (ADF) or posterior decompression with fusion (PDF) on patients with massive OPLL or kyphotic alignment, and we performed laminoplasty (LAMP) on patients without massive OPLL or kyphotic alignment. CSVA (center of gravity of the head -C7 SVA), CL (C2-7 lordotic angle) and C7 slope were measured in cervical X-ray at standing position. Clinical results were evaluated using C-JOA score. We divided patients into two sub-groups based on the preoperative CSVA: the Low-CSVA (CSVA < 40 mm) and High-CSVA (CSVA & GE;40 mm) subgroups. Results: In the Low-CSVA subgroup, none of the three operations had an effect on the CL. In contrast, in the High-CSVA subgroup, while ADF and PDF had no effect on the CL, LAMP worsened the CL post-operatively. The recovery rates of the C-JOA scores in the Low-CSVA subgroup showed no significant differences among the three operations; however in the High-CSVA subgroup, LAMP resulted in worse recovery rate of the C-JOA score than ADF or PDF. Conclusions: LAMP is not suitable for patients with cervical myelopathy caused by OPLL who have high CSVA alignment, even in cases without massive OPLL or kyphotic alignment.(C) 2021 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.

Automated summary

This study investigated the impact of SVA-based cervical sagittal alignment on surgical treatment for cervical OPLL. The results showed that in patients with high CSVA alignment, LAMP worsened the C2-7 lordotic angle post-operatively and had a lower recovery rate of the C-JOA score compared to ADF or PDF. Therefore, LAMP is not suitable for these patients.