Novel Angular Measures of Cervical Deformity Account for Upper Cervical Compensation and Sagittal Alignment.

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2017-08

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Abstract

Study design

This is a retrospective review of a prospective multicenter database.

Objective

This study introduces 2 new cervical alignment measures accounting for both cervical deformity (CD) and upper cervical compensation.

Summary of background data

Current descriptions of CD like the C2-C7 sagittal vertical axis (cSVA) do not account for compensatory mechanisms such as C0-C2 lordosis and pelvic tilt, which makes surgical planning difficult. The craniocervical angle (CCA) combines the slope of McGregor's line and the inclination from C7 to the hard palate. The C2-pelvic tilt (CPT) combines C2 tilt and pelvic tilt. Like the T1 pelvic angle, CPT is less affected by lower extremity and pelvic compensation.

Methods

Novel and existing CD measures were correlated in 781 patients from a thoracolumbar deformity (TLD) database and 61 patients from a prospective CD database. CD patients were subanalyzed by region of deformity driver: cervical or cervico-thoracic junction. TLD patients were substratified according to whether or not they had CD as well, where CD was defined as cSVA>4 cm or T1 slope minus cervical lordosis mismatch (TS-CL) >20.

Results

TLD cohort: mean cSVA was 31.7±17.8 mm. Subanalysis of TLD patients with CD versus no-CD demonstrated significant differences in CCA (56.2 vs. 60.6, P<0.001) and CPT (32.6 vs. 19.3, P<0.001). CCA and CPT correlated with cSVA (r=-0.488/r=0.418, P<0.001) and C0-C2 lordosis (r=-0.630/r=0.289,P<0.001). CD cohort: mean cSVA was 47.3±32.2 mm. CCA and CPT correlated with cSVA (r=-0.811/r=0.657, P<0.001) and C0-C2 lordosis (r=-0.656/r=0.610, P<0.001). CD cohort subanalysis indicated that CT patients were significantly more deformed by cSVA (71.3 vs 24.0 mm, P<0.001), CCA (47.1 vs 59.1 degrees, P<0.001), and CPT (63.3 vs 43.8 degrees, P=0.002). Using linear regression analysis, cSVA of 4 cm corresponded to CCA of 53.2 degrees (r=0.5) and CPT of 48.5 degrees (r=0.4).

Conclusions

CCA and CPT account for both cervical sagittal alignment and upper cervical compensation and can be utilized in assessment of cervical alignment.

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Subjects

International Spine Study Group, Pelvis, Cervical Vertebrae, Thoracic Vertebrae, Humans, Postoperative Care, Cohort Studies, Quality of Life, Aged, Middle Aged, Female, Male, Biomechanical Phenomena

Citation

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https://hdl.handle.net/10161/28398

Published Version (Please cite this version)

10.1097/bsd.0000000000000554

Publication Info

Protopsaltis, Themistocles S, Renaud Lafage, Shaleen Vira, Daniel Sciubba, Alex Soroceanu, Kojo Hamilton, Justin Smith, Peter G Passias, et al. (2017). Novel Angular Measures of Cervical Deformity Account for Upper Cervical Compensation and Sagittal Alignment. Clinical spine surgery, 30(7). pp. E959–E967. 10.1097/bsd.0000000000000554 Retrieved from https://hdl.handle.net/10161/28398.

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