Introduction: Despite successful bracing for adolescent idiopathic scoliosis (AIS), some curves progress after brace cessation. The purpose of this study was to identify the incidence, rate, and risk factors for progression after successful brace management of AIS.
Materials and Methods: Patients treated with orthoses for AIS were prospectively enrolled at brace initiation, followed through successful brace completion and, on average, for 33 months (range 12-95) after brace cessation. Inclusion criteria were curves 25° to 45° and Risser 0 to II at brace initiation with cessation at Risser IV with curves measuring <50°. Exclusion criteria were cessation before Risser IV or curve progression >50° during bracing. Demographics and radiographic measures were collected. Brace compliance was measured using Thermachron temperature sensor. Postbrace progressors were compared with nonprogressors using Mann-Whitney U test, Fisher exact test, and two-sample t-test.
Results: Eighty-five patients who completed bracing with final curves <50° were followed after brace discontinuation >1 year. Twenty-seven/85 (31.8%) progressed postbracing to surgical curve magnitude >50° (n = 12) or progressed >5° after brace cessation without progression to surgical magnitude (n = 15). There was no difference between progressors and nonprogressors in age or menarchal status at brace initiation or completion, nor was there a difference in curve magnitude or morphology at initiation. There was no difference in duration of or compliance with bracing. Patients with postbrace surgical progression completed bracing at 46° on average compared with 33° for those who did not progress to surgical magnitude (P < 0.0001). Patients who completed bracing at >45° had an incidence of postbrace surgical progression of 67%. No patients who completed bracing with curves <40° showed progression after brace cessation.
Conclusions: A total of 14.1% of patients successfully treated for AIS with bracing later progressed to surgical magnitude, and an additional 17.6% progressed >5° after brace completion. Findings suggest that patients with curves measuring >40° at brace completion should be followed into young adulthood. Counseling regarding the potential future need for surgery is warranted once a curve exceeds 45° in braced patients.
Level of Evidence: Level 2 prospective cohort study (J Prosthet Orthot. 2022;34:3-9)
Recent literature definitively supports the use of bracing for the treatment of adolescent idiopathic scoliosis (AIS) in curves measuring between 25° and 40° to 45° in skeletally immature patients. Both the BRAIST study and a report from the Texas Scottish Rite Hospital for Children found a strong correlation between brace wear compliance—measured with validated temperature sensors—and prevention of curve progression. Successful bracing of AIS has been defined as reaching skeletal maturity with an out-of-brace curve measuring <50° 1,2,4-6 as curves greater than 50° at skeletal maturity have an increased risk for progression. Thus, a curve reaching this magnitude is generally considered a surgical indication.
Despite numerous well-executed studies on the effects of bracing in AIS and factors affecting brace success, these studies often do not follow their cohorts after brace completion. As such, postbrace progression of a prospectively followed compliance-monitored cohort has not been previously reported. Natural history studies report a 0.4° to 0.56°/year progression rate after skeletal maturity with a positive correlation between magnitude of curve at skeletal maturity and rate of progression. However, these studies are based on nontreated/ observational cohorts, and there is no evidence to support that previously successfully braced curves behave similarly.
Given this void in our understanding of AIS, we sought to define the incidence of postbrace surgical progression—defined as progression to surgical curve magnitude ≥50°—after successful brace completion and to define the incidence of progression >5° after successful brace cessation. Further, we sought to identify risk factors for postbrace surgical progression in a cohort of AIS patients deemed to have successfully completed bracing at skeletal maturity (Risser IV).