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Sagittal age-adjusted score (SAAS) for adult spinal deformity (ASD) more effectively predicts surgical outcomes and proximal junctional kyphosis than previous classifications

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An Author Correction to this article was published on 23 December 2022

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Abstract

Background

Several methodologies have been proposed to determine ideal ASD sagittal spinopelvic alignment (SRS–Schwab classification) global alignment and proportion (GAP) score, patient age-adjusted alignment). A recent study revealed the ability and limitations of these methodologies to predict PJK. The aim of the study was to develop a new approach, inspired by SRS classification, GAP score, and age-alignment to improve the evaluation of the sagittal plane.

Method

A multi-center ASD database was retrospectively evaluated for surgically treated ASD patients with complete fusion of the lumbar spine, and minimum 2 year follow-up. The Sagittal age-adjusted score (SAAS) methodology was created by assigning numerical values to the difference between each patient’s postoperative sagittal alignment and ideal alignment defined by previously reported age generational norms for PI-LL, PT, and TPA. Postoperative HRQOL and PJK severity between each SAAS categories were evaluated.

Results

409 of 667 (61.3%) patients meeting inclusion criteria were evaluated. At 2 year SAAS score showed that 27.0% of the patients were under-corrected, 51.7% over-corrected, and 21.3% matched their age-adjusted target. SAAS score increased as PJK worsened (from SAAS = 0.2 for no-PJK, to 4.0 for PJF, p < 0.001). Post-operatively, HRQOL differences between SAAS groups included ODI, SRS pain, and SRS total.

Conclusion

Inspired by SRS classification, the concept of the GAP score, and age-adjusted alignment targets, the results demonstrated significant association with PJK and patient reported outcomes. With a lower rate of failure and better HRQOL, the SAAS seems to represent a “sweet spot” to optimize HRQOL while mitigating the risk of mechanical complications.

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Funding

The International Spine Study Group (ISSG) is funded through research grants from DePuy Synthes (current), Nuvasive (current), K2M (current), Innovasis (past), Biomet (past), and individual donations.

Author information

Authors and Affiliations

  1. Department of Orthopedics, Hospital for Special Surgery, 525 E 71st St., Belaire 4E, New York, NY, 10021, USA

    Renaud Lafage, Jonathan Elysee, Han Jo Kim, Frank Schwab & Virginie Lafage

  2. Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, VA, USA

    Justin S. Smith

  3. Department of Orthopedics, NYU Langone Orthopedic Hospital, New York, NY, USA

    Peter Passias

  4. Denver International Spine Center, Presbyterian St. Luke’s/Rocky Mountain Hospital for Children, Denver, CO, USA

    Shay Bess

  5. Department of Orthopaedic Surgery, University of California, Sacramento, Davis, CA, USA

    Eric Klineberg

  6. Department of Neurosurgery, Duke University Medical Center, Durham, NC, USA

    Christopher Shaffrey

  7. Department of Orthopaedics, University of Kansas Medical Center, Kansas, KS, USA

    Douglas Burton

  8. Department of Orthopaedic Surgery, Baylor Scoliosis Center, Dallas, TX, USA

    Richard Hostin

  9. Scripps Clinic, San Diego, CA, USA

    Gregory Mundis

  10. Department of Neurological Surgery, School of Medicine, University of California, San Francisco, CA, USA

    Christopher Ames

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  1. Renaud Lafage
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  2. Justin S. Smith
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  13. Frank Schwab
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on behalf of International Spine Study Group (ISSG)

Contributions

RL: conceptualization, data collection and preparation, method and analysis, writing—original draft, writing review/editing. JSS: conceptualization, data collection and preparation, writing—original draft, writing review/editing. JE: conceptualization, data collection and preparation, method and analysis, writing—original draft, writing review/editing. PP: conceptualization, data collection and preparation, writing review/editing. SB: conceptualization, data collection and preparation, Writing review/editing. EK: conceptualization, data collection and preparation, writing review/editing. HJK: conceptualization, data collection and preparation, writing—original draft, writing review/editing. CS: conceptualization, data collection and preparation, writing review/editing. DB: conceptualization, data collection and preparation, writing review/editing. RH: conceptualization, data collection and preparation, writing review/editing, GM: conceptualization, data collection and preparation, writing review/editing. CA: conceptualization, data collection and preparation, writing review/editing. FS: conceptualization, data collection and preparation, writing—original draft, writing review/editing, supervision. VL: conceptualization, data collection and preparation, method and analysis, writing—original draft, writing review/editing, supervision. All authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All authors included in the present article have substantially participate to the manuscript and approved the final version of the manuscript.

Corresponding author

Correspondence to Renaud Lafage.

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Detail conflict of interest was submitted for each author. None of them are related to the current study.

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IRB approval was obtained at each participating site.

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Informed consent was obtained from all individual participants in the study prior enrollment.

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The original online version of this article was revised: In Fig. 4 of this article signs for points associated in all 3 components are incorrect and should be reversed, e.g + 2 should be −2 and vise versa.

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Lafage, R., Smith, J.S., Elysee, J. et al. Sagittal age-adjusted score (SAAS) for adult spinal deformity (ASD) more effectively predicts surgical outcomes and proximal junctional kyphosis than previous classifications. Spine Deform 10, 121–131 (2022). https://doi.org/10.1007/s43390-021-00397-1

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