Global spinal alignment in cervical kyphotic deformity: The importance of head position and thoracolumbar alignment in the compensatory mechanism

Jun Mizutani, Kushagra Verma, Kenji Endo, Ken Ishii, Kuniyoshi Abumi, Mitsuru Yagi, Naobumi Hosogane, Jeffrey Yang, Bobby Tay, Vedat Deviren, Christopher Ames

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

BACKGROUND: Previous studies have evaluated cervical kyphosis (C-kypho) using cervical curvature or chin-brow vertical angle, but the relationship between C-kypho and global spinal alignment is currently unknown. OBJECTIVE: To elucidate global spinal alignment and compensatory mechanisms in primary symptomatic C-kypho using full-spine radiography. METHODS: In this retrospective multicenter study, symptomatic primary C-kypho patients (Cerv group; n = 103) and adult thoracolumbar deformity patients (TL group; n = 119) were compared. We subanalyzed Cerv subgroups according to sagittal vertical axis (SVA) values of C7 (SVAC7 positive or negative [C7P or C7N]). Various Cobb angles () and SVAs (mm) were evaluated. RESULTS: SVAC7 values were –20.2 and 63.6 mm in the Cerv group and TL group, respectively (P < .0001). Various statistically significant compensatory curvatures were observed in the Cerv group, namely larger lumbar lordosis (LL) and thoracic kyphosis. The C7N group had significantly lower SVACOG (center of gravity of the head) and SVAC7 (32.9 and –49.5 mm) values than the C7P group (115.9 and 45.1 mm). Sagittal curvatures were also different in T4-12, T10-L2, LL4-S, and LL. The value of pelvic incidence (PI)-LL was different (C7N vs C7P; –2.2 vs 9.9; P < .0003). Compensatory sagittal curvatures were associated with potential for shifting of SVAC7 posteriorly to adjust head position. PI-LL affected these compensatory mechanisms. CONCLUSION: Compensation in symptomatic primary C-kypho was via posterior shifting of SVAC7, small T1 slope, and large LL. However, even in C-kypho patients, lumbar degeneration might affect global spinal alignment. Thus, global spinal alignment with cervical kyphosis is characterized as head balanced or trunk balanced.

Original languageEnglish
Pages (from-to)686-694
Number of pages9
JournalNeurosurgery
Volume82
Issue number5
DOIs
Publication statusPublished - 2018 May 1
Externally publishedYes

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Keywords

  • Cervical deformity
  • Cervical vertebrae
  • Compensatory mechanism
  • Globalspinalalignmentandbalance
  • Kyphosis
  • Lumbarlordosis
  • Occiputtrunkdiscordance
  • Sagittalimbalance
  • Spinal curvatures
  • Spinopelvic parameters

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

Cite this

Mizutani, J., Verma, K., Endo, K., Ishii, K., Abumi, K., Yagi, M., Hosogane, N., Yang, J., Tay, B., Deviren, V., & Ames, C. (2018). Global spinal alignment in cervical kyphotic deformity: The importance of head position and thoracolumbar alignment in the compensatory mechanism. Neurosurgery, 82(5), 686-694. https://doi.org/10.1093/neuros/nyx288