Ossified posterior longitudinal ligament existing at an intervertebral level limits compensatory mechanism of cervical lordosis after muscle-preserving selective laminectomy

Satoshi Nori, Ryoma Aoyama, Ken Ninomiya, Satoshi Suzuki, Ukei Anazawa, Tateru Shiraishi

Research output: Contribution to journalArticle

Abstract

Introduction: As C7 slope increases, lordotic change of C2-C7 angle compensates for adjustments in cervical sagittal balance. However, ossification of the posterior longitudinal ligament (OPLL) may affect the compensatory mechanism of the cervical spine. This study aims to evaluate the impact of OPLL on cervical lordotic compensation after muscle-preserving selective laminectomy (SL). Methods: This study involved 235 patients with cervical spondylotic myelopathy (CSM) and OPLL who underwent !3 consecutive levels of SL. OPLL was classified into continuous, segmental, mixed, or localized type on the basis of the criteria previously reported. In this study, based on the motion preservation at the intervertebral level, patients were divided into CSM (n = 114), OPLL segmental type (OPLL-S; n = 44), and other types of OPLL (OPLL-O; i.e., continuous, mixed, and localized; n = 77). The cervical sagittal alignment, degree of spinal cord decompression, and surgical outcomes were compared among the three groups. Results: The OPLL-O group had a larger postoperative C7 slope (p = 0.020), larger pre- (p = 0.021) and postoperative (p = 0.001) C2-C7 sagittal vertical axis, and greater pre- (p = 0.034) and postoperative (p = 0.002) C7 slope minus C2-C7 angle. Narrower postoperative spinal cord clearance (PSCC) from OPLL (p < 0.001) and more residual spinal cord compression (p < 0.001) were observed in the OPLL-O group. Correlation between postoperative C7 slope minus C2-C7 angle and PSCC was detected (r = −0.238, p < 0.001). The recovery rate of the Japanese Orthopedic Association score was slightly lower in the OPLL-O group (p < 0.001), and it was correlated with postoperative residual spinal cord compression (r = −0.305, p < 0.001). Conclusions: OPLL-O limits cervical lordotic compensation, resulting in cervical sagittal balance mismatch. It affects the degree of spinal cord decompression, which might be related to surgical outcome.

Original languageEnglish
Pages (from-to)312-318
Number of pages7
JournalSpine Surgery and Related Research
Volume3
Issue number4
DOIs
Publication statusPublished - 2019

Keywords

  • Cervical alignment
  • Cervical lordotic compensation
  • Cervical sagittal balance mismatch
  • Cervical spondylotic myelopathy
  • Laminoplasty
  • Minimally invasive surgery
  • Muscle-preserving selective laminectomy
  • Ossification of the posterior longitudinal ligament

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology
  • Orthopedics and Sports Medicine

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