201. US AND EUROPEAN RISSER GRADING SYSTEMS: WHICH ONE BEST PREDICTS THE CURVE ACCELERATION PHASE IN ADOLESCENT IDIOPATHIC SCOLIOSIS?

Abstract

Purpose: In pediatric orthopedics, Risser sign is used to assess skeletal maturity. Two grading system exist for the Risser sign, one US and one European. In adolescent idiopathic scoliosis (AIS) the curve acceleration phase begin at a digital skeletal age (DSA) score between 400 – 425. The objective was to asses the disagreement between both grading system and evaluate the best estimator of the curve acceleration phase.

Method: One hundred twenty-one AIS patients had a PA and lateral X-rays of the spine and a left hand and wrist X-ray. Risser sign was measured according to both grading system and bone age was calculated according to Tanner-Whitehouse III method. Kappa statistics were done to evaluate concordance between US and Euro-pean grading system and 2 multiple linear regression models were performed to find which stage best predicts the beginning of the rapid acceleration phase.

Results: Kappa statistic between the US and European system was 0.517 (moderate agreement). US Risser 1 was the best predictor of the curve acceleration phase. DSA scores predicted with Risser 1 were 425 and 445 for US and European system respectively.

Conclusion: American and European Risser grading system use different criteria to define 6 stages of a same sign. This is reflected in our study with a moderate agreement between both grading systems. US Risser 1 is the stage that best predicts the beginning of the rapid acceleration phase and a close follow up should be made at the beginning of the iliac apophysis ossification.