Contrastive study of thumb ossification composite index and Risser sign in evaluating the growth potential of adolescent idiopathic scoliosis

Abstract

Objective: To compare and analyze the correlations between thumb ossification composite index (TOCI), Risser sign and digital skeletal age (DSA) scores and to verify the possibility of TOCI as a supplementary to Risser sign in the evaluation of growth potential of adolescent idiopathic scoliosis (AIS) patients. Methods: Forty-nine AIS patients undergoing bracing treatment between May 2006 and May 2014 were selected from Nanjing Drum Tower Hospital. The follow-up interval was 4-6 months. The following data at each visit were routinely collected, including TOCI and DSA scores, as well as chronologic age and standing height. The height velocity (HV) at each visit was calculated based on the above data. All results were analyzed by Spearman correlation with TOCI and Risser sign. Results: There were strong correlations between TOCI and Risser sign and DSA scores (r=0.962, 0.813, both P<0.01). In AIS patients whose Risser sign were 0-1, the correlation between TOCI and DSA scores was more pronounced, compared with the correlation between Risser sign and DSA scores (0.918 vs 0.792, P<0.01). The HV averaged (7.1±2.1) cm/year in TOCI 5, significantly larger than these in other TOCI scores (all P<0.01). Conclusions: The TOCI 5 can be a sign of high height velocity and high growth potential in AIS patients. TOCI is a valid indicator of skeletal maturity evaluation and can be used as a helpful supplementary to Risser sign, whose predictive ability may be better than Risser sign.