Flexibility Predicts Curve Progression in Providence Nighttime Bracing of Patients With Adolescent Idiopathic Scoliosis

Study Design. Retrospective cohort study. Objective. To determine treatment outcome with providence brace (PB) and to assess the ability of pretreatment supine lateral bending radiographs (SLBR) in predicting curve progression. Summary of Background Data. Results from treatment with the PB for adolescent idiopathic ccoliosis (AIS) have been inconsistent and further research is needed. The association between flexibility, as determined by pretreatment SLBR, and curve progression has not previously been examined. Methods. All patients treated with the PB from 2006 to 2011 who met Scoliosis Research Society (SRS) bracing criteria were included. Flexibility of the curve was determined based on SLBR and radiographic variables were registered at beginning of treatment and at skeletal maturity (SM) or before surgery. An increase in standing Cobb angle by more than 5 degrees was considered progression. Follow-up SRS-22 scores were compared with a control group with minor AIS. Analysis included multiple linear and logistic regression. Results. A total of 63 patients were included. Mean age was 13.3 years (SD: 1.5) and mean standing Cobb angle was 348 (SD: 5 degrees). Radiographic progression was observed in 43% of patients at SM and surgical rate was 27% and 37% at SM and 2-year follow up, respectively. SRS-22 total scores were similar but the mental health score was significantly better in the control group (P = 0.042). Multiple linear regression analysis showed that decreased flexibility adjusted for age, Cobb angle, and menarchal status was significantly associated with curve progression (P < 0.001). Multiple logistic regression analysis showed that a one percent increase in flexibility was associated with a decrease in risk of curve progression >= 6 degrees (odds ratio = 0.95; 95% confidence interval 0.90-0.98; P = 0.013). Conclusion. Progression was seen in 43% of AIS patients treated with the PB. Increase in flexibility was independently associated with a decreased risk of progression.