Journal of Craniovertebral Junction and Spine (Jan 2021)

Effect of age-adjusted alignment goals and distal inclination angle on the fate of distal junctional kyphosis in cervical deformity surgery

  • Peter Gust Passias,
  • Samantha R Horn,
  • Virginie Lafage,
  • Renaud Lafage,
  • Justin S Smith,
  • Breton G Line,
  • Themistocles S Protopsaltis,
  • Alex Soroceanu,
  • Cole Bortz,
  • Frank A Segreto,
  • Waleed Ahmad,
  • Sara Naessig,
  • Katherine E Pierce,
  • Avery E Brown,
  • Haddy Alas,
  • Han Jo Kim,
  • Alan H Daniels,
  • Eric O Klineberg,
  • Douglas C Burton,
  • Robert A Hart,
  • Frank J Schwab,
  • Shay Bess,
  • Christopher I Shaffrey,
  • Christopher P Ames

DOI
https://doi.org/10.4103/jcvjs.jcvjs_170_20
Journal volume & issue
Vol. 12, no. 1
pp. 65 – 71

Abstract

Read online

Background: Age-adjusted alignment targets in the context of distal junctional kyphosis (DJK) development have yet to be investigated. Our aim was to assess age-adjusted alignment targets, reciprocal changes, and role of lowest instrumented level orientation in DJK development in cervical deformity (CD) patients. Methods: CD patients were evaluated based on lowest fused level: cervical (C7 or above), upper thoracic (UT: T1–T6), and lower thoracic (LT: T7–T12). Age-adjusted alignment targets were calculated using published formulas for sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), pelvic tilt (PT), T1 pelvic angle (TPA), and LL-thoracic kyphosis (TK). Outcome measures were cervical and global alignment parameters: Cervical SVA (cSVA), cervical lordosis, C2 slope, C2–T3 angle, C2–T3 SVA, TS-CL, PI-LL, PT, and SVA. Subanalysis matched baseline PI to assess age-adjusted alignment between DJK and non-DJK. Results: Seventy-six CD patients included. By 1Y, 20 patients developed DJK. Non-DJK patients had 27% cervical lowest instrumented vertebra (LIV), 68% UT, and 5% LT. DJK patients had 25% cervical, 50% UT, and 25% LT. There were no baseline or 1Y differences for PI, PI-LL, SVA, TPA, or PT for actual and age-adjusted targets. DJK patients had worse baseline cSVA and more severe 1Y cSVA, C2–T3 SVA, and C2 slope (P < 0.05). The distribution of over/under corrected patients and the offset between actual and ideal alignment for SVA, PT, TPA, PI-LL, and LL-TK were similar between DJK and non-DJK patients. DJK patients requiring reoperation had worse postoperative changes in all cervical parameters and trended toward larger offsets for global parameters. Conclusion: CD patients with severe baseline malalignment went on to develop postoperative DJK. Age-adjusted alignment targets did not capture differences in these populations, suggesting the need for cervical-specific goals.

Keywords