• Seung-Jae Hyun, Sanghyun Han, Ki-Jeong Kim, Tae-Ahn Jahng, and Hyun-Jib Kim.
• Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea.
• Oper Neurosurg (Hagerstown). 2019 Jan 1; 16 (1): 20-26.

BackgoundRecently, previous research proposed a cervical spine deformity (CSD) classification using a modified Delphi approach. However, C2-C7 sagittal vertical axis (SVA) and T1 slope minus C2-C7 lordosis (TS-CL) cut-off values for moderate and severe disability were based on expert opinion.ObjectiveTo investigate the validity of a CSD classification system.MethodsFrom 2007 to 2012, 30 consecutive patients with a minimum 5-yr follow-up having 3- or more level posterior cervical fusion met inclusion criteria. The following radiographic parameters were measured: C0-C2 lordosis, C2-C7 lordosis, C2-C7 SVA, T1 slope, and TS-CL. Pearson correlation coefficients were calculated between pairs of radiographic measures and health-related quality of life.ResultsAverage follow-up period was 7.3 yr. C2-C7 SVA positively correlated with neck disability index (NDI) scores (r = 0.554). Regression models predicted a threshold C2-C7 SVA value of 40.8 mm and 70.6 mm correlated with moderate and severe disability based on the NDI score, respectively. The TS-CL had positive correlation with C2-C7 SVA and NDI scores (r = 0.841 and r = 0.625, respectively). Regression analyses revealed that a C2-C7 SVA value of 40 mm and 70 mm corresponded to a TS-CL value of 20° and 25°, respectively.ConclusionRegression models predicted a threshold C2-C7 SVA (value of 40.8 mm and 70.6 mm) and TS-CL (value of 20° and 25°) correlated with moderate and severe disability based on the NDI, respectively. The cut-off value C2-C7 SVA and TS-CL modifier of the CSD classification can be revised accordingly.

22 keywords...

hide…