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Validation of a Simplified SRS-Schwab Classification Using a Sagittal Modifier

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Abstract

Study Design

Multicenter, prospective study of consecutive adult spinal deformity (ASD) patients.

Objective

To Validate Schwab’s classification accuracy for surgical indication, and to evaluate a simplified sagittal modifier.

Summary of Background Data

The SRS-Schwab Radiologic Classification based on clinical impact parameters, offers 27 different sagittal classification possibilities regarding sagittal vertical alignment (SVA), pelvic tilt (PT), and pelvic incidence—lumbar lordosis (PILL). The high number of classification possibilities makes it complex to use.

Methods

Inclusion criteria were ASD patients, presenting at least 1 criteria: Cobb ≥ 20°, SVA ≥ 5 cm, thoracic kyphosis ≥ 60°, or PT ≥ 25°. A total of 1,004 patients (410 nonoperative and 594 operative) were classified regarding SVA, PT, and PI-LL (0, +, ++), and 27 possibilities were identified. Categories were formed by adding the number of + signs, considering PT, SVA, and PI-LL. Three specific categories were identified: Aligned: 0 +; Moderate deformity: 1 to 3+; and Severe deformity: 4 to 6+. A χ-square test was performed for surgical indication (operated or not) and an analysis of variance was performed to evaluate the relationship between categories and Oswestry Disability Index (ODI). Probability <.05 was considered significant.

Results

Significant differences for HRQoL scores and surgical indication were found in the 27 sagittal parameter possibilities. For nonoperative patients, 230 (56.1%) were classified as aligned, 145 (35.4%) as moderate, and 35 (8.5%) as severe. For operative patients, there were 200 (33.7%), 215 (36.2%), and 179 (30.1%) in each respective subgroup. For HRQoL scores and surgical indication, no significant differences were found within each category, but significant differences were found when comparing the subgroups.

Conclusions

Despite the correlation between SRS-Schwab classification and surgical indication, it is complex to use, with a total of 27 possibilities regarding sagittal modifiers. This simplification into three categories offers more readability, without losing any significant information, and could replace Schwab sagittal modifiers. In association with other parameters, they could be used for decision-making.

Level of Evidence

Level II.

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Authors and Affiliations

  1. Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch School of Medicine, Christchurch, New Zealand

    D. C. Kieser MBChB, FRACS, PhD

  2. Spine Unit 1, Bordeaux University Hospital, Bordeaux, France

    L. Boissiere MD, D. T. Cawley FRCS, D. Larrieu PhD, M. Takemoto MD, G. Yoshida MD, J. M. Vital MD, PhD & I. Obeid MD

  3. ELSAN, Polyclinique Jean Villar, Bruges, France

    D. Larrieu PhD

  4. Department of Orthopedics and Traumatology, Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey

    C. Yilgor MD & A. Alanay MD

  5. Ankara ARTES Spine Center, Ankara, Turkey

    E. Acaroglu MD

  6. Research and Development, Schulthess Klinik, Zurich, Switzerland

    F. Kleinstü MD

  7. Spine Surgery Unit, Hospital Universitario Val Hebron, Barcelona, Spain

    F. Pellisé MD

  8. Spine Surgery Unit, Hospital Universitario La Paz, Madrid, Spain

    F. J. S. Perez-Grueso MD

Authors
  1. D. C. Kieser MBChB, FRACS, PhD
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  2. L. Boissiere MD
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  3. D. T. Cawley FRCS
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  4. D. Larrieu PhD
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  5. C. Yilgor MD
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  6. M. Takemoto MD
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  7. G. Yoshida MD
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  8. A. Alanay MD
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  9. E. Acaroglu MD
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  10. F. Kleinstü MD
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  11. F. Pellisé MD
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  12. F. J. S. Perez-Grueso MD
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  13. J. M. Vital MD, PhD
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  14. I. Obeid MD
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Consortia

on behalf of the European Spine Study Group (ESSG)

Corresponding author

Correspondence to D. C. Kieser MBChB, FRACS, PhD.

Additional information

Author disclosures: DCK (none), LB (none), DTC (none), DL (none), CY (none),MT(none),GY(none),AA(none),EA(none),FK(none),FP(none),FJSPG (none), JMV (none), IO (none), European Spine Study Group (ESSG) (none).

IRB ethical approval: Institutional review board approval for patient inclusion in this database was obtained by each of the sites that contributed patient information. Each patient signed a consent document before inclusion.

Funding: None.

The authors thank Glynny Kieser for her editorial input.

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Kieser, D.C., Boissiere, L., Cawley, D.T. et al. Validation of a Simplified SRS-Schwab Classification Using a Sagittal Modifier. Spine Deform 7, 467–471 (2019). https://doi.org/10.1016/j.jspd.2018.09.008

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  • DOI: https://doi.org/10.1016/j.jspd.2018.09.008

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