Development and initial validation of classification for severe spinal deformity based on X-ray features.

Abstract

To develop a clinically feasible classification for severe spinal deformity based on X-ray features. A total of 223 consecutive severe spinal deformity cases who underwent corrective operation were enrolled from 2004 to 2015 retrospectively. Based on X-ray features, a novel classification was developed containing three components: curve types, curve angle and apex location. There were five curve types as follows: single scoliosis (SS), kyphoscoliosis (KS), angular deformity (AD), long curve (LC), and double curves (DC). Curve angle subsection on coronal and sagittal planes including A:90-109, B:110-129, C:130-149, D: > 150. Apex location means the exact level of apex located. Reliability of the classification was tested. The kappa values for inter-observer and intra-observer reliability of the curve types, curve angle, and apex level were larger than 0.80. X-ray classification for overall patients with severe spinal deformity showed that there were 101 SS cases, 47 KS, 46 AD, 19 LC and 10 DC. For the curve angle, there were grade A 123 cases, B 43, C 18, D 15 on coronal plane and grade A 38, B 17, C 16, and D 19 on sagittal plane. Apex location showed there were 27 patients at T7 or upper levels, 31 on T8, 58 on T9, 45 on T10, 18 on T11, and 44 at T12 or lower levels. A novel classification for severe spinal deformity was described based on X-ray morphology. A high value for inter-observer and intra-observer reliability was shown. Each subgroup has its particular influence on decision-making and prognostic prediction.