Characteristics of functional movements after brace treatment for adolescent idiopathic scoliosis and development of a nomogram prediction model of factors influencing efficacy

English Keywords:Adolescent idiopathic scoliosis  Brace therapy  Functional action characteristics  Scoliosis progression

English Abstract:

  【Abstract】 Objectives: To analyze the functional movement characteristics after brace treatment for patients with adolescent idiopathic scoliosis(AIS), and to develop and validate a nomogram model to predict the risk of poor outcome. Methods: AIS patients who were treated with braces at our institution from March 2020 to March 2022 were collected as a training set, and were tested for functional movement before treatment, at initial follow-up and after treatment. The same criteria were used to collect AIS patients who underwent brace treatment in our hospital from April 2022 to August 2022 as the validation set. On the basis of whether the degree of scoliosis progression was >5° after 1 year of treatment, the patients in the training set were divided into stable(≤5°) and progressive(>5°) groups. Comparison of data was made between groups. Spearman correlation analysis was used to analyze the correlation between variables. Logistic regression model was used to screen the risk factors for poor outcomes. R software was applied to develop a nomogram prediction model. Area under curve(AUC) of receiver operating characteristic(ROC) curve and calibration curve were applied to evaluate the discrimination and accuracy of the model. Internal validation was performed with the model predicted risk values before and after training set Bootstrap self-sampling as the test variables and the actual prognosis of patients as the state variable; External validation of the model was performed after randomization of the validation set Bootstrap self-sampling. Results: A total of 102 patients with AIS were included in the training set. There were 73 cases in the stable group and 29 cases in the progressive group(range of degrees of progression: 8° to 27°). The median follow-up time was 15.4 months. Both thoracic and lumbar Cobb angles decreased significantly after treatment(P<0.05). Rotational stability and push-ups were higher at initial follow-up than before treatment, and scores on bow-step squat, hurdle striding, rotational stability, and push-ups improved after treatment(P<0.05). There was no significant correlation between functional movement characteristics and Cobb angle(P>0.05). Pre-treatment Cobb angle≥35°, Risser′s sign≥3°, apex rotation≥degree Ⅲ, and spinal length gain≥20mm/year were independent risk factors for scoliosis progression. Lumbar spine bone density≥0.8g/cm2 and spinal flexibility≥50% were protective factors. The total value of the risk of scoliosis progression after brace treatment predicted by the nomogram model was 0.93. The AUCs before and after training set self-sampling were 0.928(95% CI: 0.858-0.998) and 0.926(95% CI: 0.854-0.997), respectively. The validation set included 37 patients. The external validation AUC for validation set was 0.891(95% CI: 0.857-0.998). The calibration curves all showed good degree of fitting. Conclusions: Patients with AIS have poor movement patterns due to spinal restrictions. Brace treatment improves trunk stability and rotational stability, which has good corrective effects on the movement pattern. AIS patients with Cobb angle≥35°, Risser′s sign≥3°, apex rotation≥degree Ⅲ, spinal length gain≥20mm/year, lumbar spine bone mineral density<0.8g/cm2, and spinal flexibility<50% before treatment who underwent bracing are prone to scoliosis progression. Timely warning shall be made based on the nomogram model and postural correction needs to be supplemented at appropriate time to improve the prognosis of AIS brace treatment.