Redefining cervical spine deformity classification through novel cutoffs: An assessment of the relationship between radiographic parameters and functional neurological outcomes

Peter Gust Passias; Katherine E Pierce; Avery E Brown; Cole A Bortz; Haddy Alas; Renaud Lafage; Virginie Lafage; Breton Line; Eric O Klineberg; Douglas C Burton; Robert Hart; Alan H Daniels; Shay Bess; Bassel Diebo; Themistocles Protopsaltis; Robert Eastlack; Christopher I Shaffrey; Frank J Schwab; Justin S Smith; Christopher Ames; On Behalf Of The International Spine Study Group

doi:10.4103/jcvjs.jcvjs_22_21

Redefining cervical spine deformity classification through novel cutoffs: An assessment of the relationship between radiographic parameters and functional neurological outcomes

J Craniovertebr Junction Spine. 2021 Apr-Jun;12(2):157-164. doi: 10.4103/jcvjs.jcvjs_22_21. Epub 2021 Jun 10.

Authors

Peter Gust Passias¹, Katherine E Pierce¹, Avery E Brown¹, Cole A Bortz¹, Haddy Alas¹, Renaud Lafage², Virginie Lafage², Breton Line³, Eric O Klineberg⁴, Douglas C Burton⁵, Robert Hart⁶, Alan H Daniels⁷, Shay Bess³, Bassel Diebo⁸, Themistocles Protopsaltis⁹, Robert Eastlack¹⁰, Christopher I Shaffrey¹¹, Frank J Schwab², Justin S Smith¹², Christopher Ames¹³, On Behalf Of The International Spine Study Group³

Affiliations

¹ Department of Orthopaedic and Neurologic Surgery, NYU Langone Orthopedic Hospital, New York Spine Institute, New York, NY, USA.
² Department of Orthopedics, Hospital for Special Surgery, New York, NY, USA.
³ Department of Spine Surgery, Denver International Spine Center, Presbyterian St. Luke's/Rocky Mountain Hospital for Children, Denver, Colorado, USA.
⁴ Department of Orthopaedic Surgery, University of California, Davis, Davis, USA.
⁵ Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City, KS, USA.
⁶ Department of Orthopaedic Surgery, Swedish Neuroscience Institute, Seattle, WA, USA.
⁷ Department of Orthopaedic Surgery, Warren Alpert School of Medicine, Brown University, Providence, RI, USA.
⁸ Department of Orthopaedic Surgery, SUNY Downstate Medical Center, New York, NY, USA.
⁹ Department of Orthopaedics, NYU Langone Orthopedic Hospital, New York, NY, USA.
¹⁰ Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, USA.
¹¹ Departments of Neurosurgery and Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA.
¹² Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA.
¹³ Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA.

Abstract

Purpose: The aim is to investigate the relationship between cervical parameters and the modified Japanese Orthopedic Association scale (mJOA).

Materials and methods: Surgical adult cervical deformity (CD) patients were included in this retrospective analysis. After determining data followed a parametric distribution through the Shapiro-Wilk Normality (P = 0.15, P > 0.05), Pearson correlations were run for radiographic parameters and mJOA. For significant correlations, logistic regressions were performed to determine a threshold of radiographic measures for which the correlation with mJOA scores was most significant. mJOA score of 14 and <12 reported cut-off values for moderate (M) and severe (S) disability. New modifiers were compared to an existing classification using Spearman's rho and logistic regression analyses to predict outcomes up to 2 years.

Results: A total of 123 CD patients were included (60.5 years, 65%F, 29.1 kg/m²). For significant baseline factors from Pearson correlations, the following thresholds were predicted: MGS (M:-12 to-9° and 0°-19°, P = 0.020; S: >19° and <-12°, χ²= 4.291, P = 0.036), TS-CL (M: 26°to 45°, P = 0.201; S: >45°, χ²= 7.8, P = 0.005), CL (M:-21° to 3°, χ²= 8.947, P = 0.004; S: <-21°, χ²= 9.3, P = 0.009), C2-T3 (M: -35° to -25°, χ²= 5.485, P = 0.046; S: <-35°, χ²= 4.1, P = 0.041), C2 Slope (M: 33° to 49°, P = 0.122; S: >49°, χ²= 5.7, P = 0.008), and Frailty (Mild: 0.18-0.27, P = 0.129; Severe: >0.27, P = 0.002). Compared to existing Ames- International Spine Study Group classification, the novel thresholds demonstrated significant predictive value for reoperation and mortality up to 2 years.

Conclusions: Collectively, these radiographic values can be utilized in refining existing classifications and developing collective understanding of severity and surgical targets in corrective surgery for adult CD.

Keywords: Adult cervical deformity; cervical spine; thresholds of severity.