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

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.