The values of initial angle velocity following bracing in the prediction of bracing outcome in adolescent idiopathic scoliosis

English Keywords:Adolescent idiopathic scoliosis  Initial angle velocity  Initial correction rate  Bracing outcome

English Abstract:

  【Abstract】 Objectives: To compare the correlation of initial angle velocity(IAV) following bracing and the initial correction rate with bracing outcome in adolescent idiopathic scoliosis(AIS) patients, and to evaluate the values of IAV in the prediction of bracing outcome in AIS patients. Methods: 126 braced AIS girls were included in this study. The curve patterns were single thoracic curves in 74 patients and thoracolumbar curves in 52 patients. The Cobb angle and Risser sign of each visit were measured on the standing x-rays. The following data were collected: chronologic age, stage of menses and standing height. Patients were divided into two groups: 55 patients in progressive(curve progression ≥6°) group and 71 patients in non-progressive(curve progression <6°) group. The IAV was defined as the angle velocity at the second visit following the prescription of orthosis, and the initial correction rate was defined as the correction rate of Cobb angle at the second visit. The independent t test was used for comparison and the logistic regression analysis was applied to identify the predictive factors of bracing outcome. Results: Among the 126 AIS patients, the average chronologic age, age at menarche, standing height, Risser sign and Cobb angle at the first visit was 12.4±1.6 years, 12.3±1.2 years, 154.4±9.7cm, 2.1±1.7 and 24.4°±6.1°, respectively. The average Cobb angle at the last visit was 29.2°±8.4°. The independent t test showed no significant difference between two groups including chronologic age, age at menarche, standing height, Risser sign or Cobb angle at the first visit(P>0.05). however, significant difference was found between non-progressive and progressive group in terms of IAV(-9.9°±13.8°/year VS 5.2°±12.5°/year, P<0.001) and initial correction rate[(11.6±16.9)% VS (-5.3±16.4)%，P<0.001]. Logistic regression analysis revealed that the initial AV(OR=8.451, P=0.004) was significantly correlated with the bracing outcome instead of initial correction rate(OR=2.192, P=0.139). Conclusions: The IAV serves as a better predictor for curve progression than initial correction rate in braced AIS patients. High IAV indicates high risk of failure bracing outcome.