Neurospine.  2021 Sep;18(3):506-514. 10.14245/ns.2040540.270.

Prioritization of Realignment Associated With Superior Clinical Outcomes for Cervical Deformity Patients

• Pierce KE
• Passias PG
• Brown AE
• Bortz CA
• Alas H
• Passfall L
• Krol O
• Kummer N
• Lafage R
• Chou D
• Burton DC
• Line B
• Klineberg E
• Hart R
• Gum J
• Daniels A
• Hamilton K
• Bess S
• Protopsaltis T
• Shaffrey C
• Schwab FA
• Smith JS
• Lafage V
• Ames C
• on behalf of the International Spine Study Group (ISSG)

• KMID: 2520959
• DOI: http://doi.org/10.14245/ns.2040540.270

Abstract

Objective
To prioritize the cervical parameter targets for alignment.
Methods
Included: cervical deformity (CD) patients (C2–7 Cobb angle > 10°, cervical lordosis > 10°, cervical sagittal vertical axis [cSVA] > 4 cm, or chin-brow vertical angle > 25°) with full baseline (BL) and 1-year (1Y) radiographic parameters and Neck Disability Index (NDI) scores; patients with cervical [C] or cervicothoracic [CT] Primary Driver Ames type. Patients with BL Ames classified as low CD for both parameters of cSVA ( < 4 cm) and T1 slope minus cervical lordosis (TS–CL) ( < 15°) were excluded. Patients assessed: meeting minimum clinically important differences (MCID) for NDI ( < -15 ΔNDI). Ratios of correction were found for regional parameters categorized by primary Ames driver (C or CT). Decision tree analysis assessed cutoffs for differences associated with meeting NDI MCID at 1Y.
Results
Seventy-seven CD patients (mean age, 62.1 years; 64% female; body mass index, 28.8 kg/m²). Forty-one point six percent of patients met MCID for NDI. A backwards linear regression model including radiographic differences as predictors from BL to 1Y for meeting MCID for NDI demonstrated an R² of 0.820 (p = 0.032) included TS–CL, cSVA, McGregor’s slope (MGS), C2 sacral slope, C2–T3 angle, C2–T3 SVA, cervical lordosis. By primary Ames driver, 67.5% of patients were C, and 32.5% CT. Ratios of change in predictors for MCID NDI patients for C and CT were not significant between the 2 groups (p > 0.050). Decision tree analysis determined cutoffs for radiographic change, prioritizing in the following order: ≥ 42.5° C2–T3 angle, > 35.4° cervical lordosis, < -31.76° C2 slope, < -11.57-mm cSVA, < -2.16° MGS, > -30.8-mm C2–T3 SVA, and ≤ -33.6° TS–CL.
Conclusion
Certain ratios of correction of cervical parameters contribute to improving neck disability. Prioritizing these radiographic alignment parameters may help optimize patient-reported outcomes for patients undergoing CD surgery.

Keyword

Spine; Cervical deformity; Alignment