General Session: Adult Spinal Deformity

Presented by: D. Stein - View Audio/Video Presentation (Members Only)

Author(s):

D. Stein(1), H. Bao(1), R. Lafage(1), B. Diebo(2), S. Ramchandran(3), L. Day(4), C. Jalai(3), D. Cruz(3), T. Errico(3), T. Protopsaltis(3), P. Passias(3), A. Buckland(3), F. Schwab(1), V. Lafage(1)

(1) Hospital for Special Surgery, Spine Service, New York, NY, United States
(2) State University of New York (SUNY) , New York, NY, United States
(3) NYU Langone Medical Center, New York, NY, United States
(4) SUNY Downstate Medical Center, Department of Orthopaedic Surgery, Brooklyn, NY, United States

Abstract

Introduction and Purpose: While cervical kyphosis has traditionally been used as the predominant radiographic marker for Cervical Spine Deformity (CSD), an increasing number of studies have reported a lack of strong between cervical kyphosis, on its own, and health related quality of life (HRQOL) scores. The purpose of this study was first to evaluate the radiographic characteristics for CSD and their relationship to HRQOL scores, and then to investigate how these findings fit in the context of the recently developed CSD classification.

Methods: This study is a retrospective review of a single center database. 171 patients (mean age 44 y/o) without previous cervical surgery, with a well aligned thoracolumbar profile (defined as T1 pelvic angle (TPA) < 15°) and with an available Neck Disability Index (NDI) score were reviewed. Subjects were stratified into an asymptomatic (64 subjects with NDI≤15, VAS neck≤3, and VAS arm≤3) and a symptomatic group (107 subjects with NDI>15, VAS neck>3, or VAS arm>3). Independent t-tests were performed to investigate differences between two groups. Logistic regressions and principal component analyses (PCA) were then performed.

Results: NDI averaged 5.43 in asymptomatic group, significantly smaller than that in symptomatic group (5.43 vs. 41.25, p< 0.001). T-test revealed that C2-C7 SVA, McGregor slope (McGS) the slope of line of sight (SLS) were significantly different across groups while C2C7 angle (Cervical curvature, CC) did not show statistical difference (p=0.09). Logistic regressions were then performed using the significantly different parameters as well as CC. Results identified C2-C7 SVA and SLS as independent risk factors for low HRQoL[VL1] . The principal component analysis led to a new factor (0.55×C2C7 SVA+0.34×C0C2+0.77×CC) with strong correlations with NDI, VAS and EQ5D measurements.

Conclusion: The conventional approach focusing on cervical curvature only in the setting of CSD may not be able to distinguish between different HRQOL statuses. C2-C7 SVA and gaze parameters should be considered simultaneously in the evaluation of a HRQOL-defined CSD, bringing clinical evidence to the new CSD classification. According to PCA analysis, cervical alignment components are more correlated with HRQOL scores than gaze components, indicating that the cervical alignment component, calculated as 0.55×C2C7 SVA+0.34×C0C2+0.77 CC, contributes more to HRQOL scores. In addition, CC, as an integral part of describing cervical alignment, should be evaluated together in harmony with the three alignment parameters, C2-C7 SVA, CC and C0C2.

Table