The Value of Different Risser Grading Systems in Determining Growth Maturity of Girls with Adolescent Idiopathic Scoliosis

A grading system for ossification of the iliac apophysis (Risser sign) was developed for skeletal maturity assessment in the United States (US) then adopted with modifications in France (Fr) and other countries. Despite the same name, these systems have important differences. With the aim to analyzing the difference between US and Fr Risser grading systems in determining the growth maturity of girls with adolescent idiopathic scoliosis (AIS), Fifty-three AIS girls undergoing posterior spinal correction with autogenous bone graft were recruited. The Risser grades were recorded for the non-dominant side iliac crest apophysis according to the US and Fr grading systems. Growth activity was determined by standard histologic grades (HGs) on iliac crest cartilage. As a result, Kappa statistics showed poor agreement between two grading systems. The US system showed higher correlation with HGs compared to Fr system by Spearman correlation analysis. It was also found that growth cessation could be determined by Risser grade 5 of US system or Risser grade 4 of Fr system. Furthermore, by employing Receiver Operating Characteristic (ROC) curve analysis, it was found that the Risser grade 4-5 of US system with two years after menarche could be used in determining growth cessation with the highest sensitivity, specificity and accuracy. Hence it was concluded that the US Risser grading system was better in determining maturity of girls with AIS than Fr Risser grading system. By combining years since menarche, the accuracy of Risser grades in determining growth cessation could be enhanced, and the time of weaning from a brace could be advanced.