Journal of Craniovertebral Junction and Spine (Jan 2020)

Radiographic benefit of incorporating the inflection between the cervical and thoracic curves in fusion constructs for surgical cervical deformity patients

  • Cole Bortz,
  • Peter G Passias,
  • Katherine Elizabeth Pierce,
  • Haddy Alas,
  • Avery Brown,
  • Sara Naessig,
  • Waleed Ahmad,
  • Renaud Lafage,
  • Christopher P Ames,
  • Bassel G Diebo,
  • Breton G Line,
  • Eric O Klineberg,
  • Douglas C Burton,
  • Robert K Eastlack,
  • Han Jo Kim,
  • Daniel M Sciubba,
  • Alex Soroceanu,
  • Shay Bess,
  • Christopher I Shaffrey,
  • Frank J Schwab,
  • Justin S Smith,
  • Virginie Lafage

DOI
https://doi.org/10.4103/jcvjs.JCVJS_57_20
Journal volume & issue
Vol. 11, no. 2
pp. 131 – 138

Abstract

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Purpose: The aim is to assess the relationship between cervicothoracic inflection point and baseline disability, as well as the relationship between clinical outcomes and pre- to postoperative changes in inflection point. Methods: Cervical deformity (CD) patients with baseline and 3-month (3M) postoperative radiographic, clinical, and inflection data were grouped by region of inflection point: C6 or above, C6-C7 to C7-T1, T1, or below. Inflection was defined as: Distal-most level where cervical lordosis (CL) changes to thoracic kyphosis (TK). Differences in alignment and patient factors across pre- and postoperative inflection point groups were assessed, as were outcomes by the inclusion of inflection in the CD-corrective fusion construct. Results: A total of 108 patients were included. Preoperative inflection breakdown: C6 or above (42%), C6-C7 to C7-T1 (44%), T1 or below (15%). Surgery was associated with a caudal migration of inflection by 3M: C6 or above (8%), C6-C7 to C7-T1 (58%), T1 or below (33%). For patients with preoperative inflection T1 or below, the inclusion of inflection in the fusion construct was associated with improvements in horizontal gaze (McGregor's Slope included: −11.3° vs. not included: 1.6°, P = 0.038). The inclusion of preoperative inflection in fusion was associated with the superior cervical sagittal vertical axis (cSVA) changes for C6-C7 to C7-T1 patients (−5.2 mm vs. 3.2 mm, P = 0.018). The location of postoperative inflection was associated with variation in 3M alignment: Inflection C6 or above was associated with less Pelvic Tilt (PT), PT and a trend of larger cSVA. Location of inflection or inclusion in fusion was not associated with reoperation or distal junctional kyphosis. Conclusions: Incorporating the inflection point between CL and TK in the fusion construct was associated with superior restoration of cervical alignment and horizontal gaze for surgical CD patients.

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