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Effect of age-adjusted alignment goals and distal inclination angle on the fate of distal junctional kyphosis in cervical deformity surgery
Peter Gust Passias1, Samantha R Horn1, Virginie Lafage2, Renaud Lafage2, Justin S Smith3, Breton G Line4, Themistocles S Protopsaltis1, Alex Soroceanu5, Cole Bortz1, Frank A Segreto1, Waleed Ahmad1, Sara Naessig1, Katherine E Pierce1, Avery E Brown1, Haddy Alas1, Han Jo Kim2, Alan H Daniels6, Eric O Klineberg7, Douglas C Burton8, Robert A Hart9, Frank J Schwab2, Shay Bess4, Christopher I Shaffrey3, Christopher P Ames10
1 Department of Orthopaedics, NYU Medical Center-Orthopaedic Hospital, New York City, NY, USA
2 Department of Orthopaedic Surgery, Hospital for Special Surgery, New York City, NY, USA
3 Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, VA, USA
4 Department of Spine Surgery, Denver International Spine Clinic, Denver, Colorado, USA
5 Department of Orthopaedic Surgery, University of Calgary, Calgary, Canada
6 Department of Orthopaedic Surgery, Warren Alpert School of Medicine, Brown University, Providence, RI, USA
7 Department of Orthopaedic Surgery, University of California, Davis, USA
8 Department of Orthopaedic Surgery, University of Kansas Medical Center, Kansas City, Kansas, USA
9 Department of Orthopaedic Surgery, Swedish Neuroscience Institute, Seattle, WA, USA
10 Department of Neurological Surgery, University of California, San Francisco, CA, USA
Correspondence Address:
Peter Gust Passias
Department of Orthopaedic and Neurological Surgery, NYU Medical Center-Orthopaedic Hospital, New York Spine Institute, 301 East 17th Street, New York, NY 10003
USA
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jcvjs.jcvjs_170_20
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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.
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