Introduction: Despite that cervical kyphosis was traditionally recognized as the presentation of cervical deformity, increasing studies demonstrated that cervical kyphosis may not imply definitely cervical deformity and may be a potential mechanism to maintain horizontal gaze. Therefore several other criteria for cervical deformity should be investigated, especially based on health‐related quality of life (HRQOL). This study aims to propose radiographic characteristics of patients with cervical disability and to investigate the relevant parameters when assessing cervical alignment.
Methods: Patients (pts) with normal thoracolumbar alignment (T1 pelvic angle < 15°), Neck Disability Index (NDI) and no prior cervical surgery were included. Pts were stratified into cervical asymptomatic (Asymp: NDI≤15, VAS neck≤3 and VAS arm≤3) or symptomatic (Symp: NDI >15 or VAS neck > 3 or VAS arm >3) groups. Sagittal parameters including SLS (Slope of Line of Sight), McGS (McGregor Slope), and CC (C2‐C7 cervical curvature) were compared between groups. Logistic regression and principle component analysis (PCA) were performed to distinguish cervical symptomatic pts.
Results: There were 171 Patients (mean 44 y/o) included, with groups Asymp N = 64 and Symp N = 107. Symp pts were older (35y vs. 50y; p < 0.001) and had worse NDI (5.4 vs. 41.3, p < 0.001). C2‐C7 SVA, McGS and SLS were significantly different between groups (all p < 0.05), while CC was comparable (p = 0.09). Logistic regression revealed that C2‐C7 SVA (OR = 1.043, p = 0.049) and SLS (OR = 0.936, p = 0.029) were independent risk factors for poor HRQOL. Using PCA, the equation 0.55×C2C7 SVA + 0.34×C0C2 angle + 0.77×CC was calculated and showed significant correlations with NDI, VAS‐Arm, VAS‐Back and EQ5D scores (r = 0.30, 0.26, 0.24 and 0.28, respectively). ROC analysis revealed improved predictability of regression and PCA formulas formula for HRQOL compared to single radiographic parameters.
Conclusion: CC alone is unable to distinguish different cervical HRQOL status and thus should not be regarded as the only criteria for CSD. Gaze parameters should be integrated in evaluation of HRQOLdefined CSD, although the predictability of gaze parameters is lower than that of cervical alignment. This data supports the integration of both gaze and alignment parameters into cervical spinal deformity classification.