Optimizing the brace-weaning criteria in adolescent idiopathic scoliosis: The role of utilizing the new Sanders 7b staging

Abstract

Purpose: There is no recommended guideline for brace weaning in adolescent idiopathic scoliosis (AIS). Curve progression after weaning may reach 46%. The Sanders staging (SS) method is widely used internationally but has yet to be acknowledged as an indicator for brace weaning. The addition of the ulna physis may further refine SS for optimizing brace weaning outcomes. The study aimed to investigate whether including the stages of ulnar physeal closure in SS7 aids in a more accurate assessment for brace weaning for patients with AIS. Methods: This was a retrospective analysis of patients who weaned brace-wear and consulted from June 2016 to December 2018. Patients who weaned brace-wear at Risser stage ≥4, static standing body height, and arm span for at least 6 months and ≥2-years post-menarche were included. Skeletal maturity at weaning was assessed using Sanders staging with SS7 subclassified into SS7a (all phalangeal physes are fused and only distal radial physes are open, with narrowing of medial physeal plate of the distal ulna) and SS7b (those with >50 % fusion of the medial growth plate of distal ulna). Weaning maturity grading and any curve progression were analyzed using Fisher’s exact test, with Cramer’s V and Goodman and Kruskal’s tau. Results: A total of 179 AIS patients (83.2% females) were studied with a mean age of 14.8±1.1 years and Cobb angle of 34.6°±7.7° at weaning. The follow-up period was 3.4±1.8 years. At post-weaning 6-months, curve progression rates for patients weaning at SS7a versus SS7b were 11.4% and 0%, respectively for <40° curves. The use of SS6, SS7a/ b, SS8 for maturity assessment at weaning strongly associated (Cramer’s V, 0.326; p=0.016) with whether the curve progressed at post-weaning 6-months. Weaning with SS7 subclassification allowed a 10.6% reduction of error in predicting curve progression. Conclusions: The use of SS7a and SS7b allows accurate maturity assessment for guiding brace weaning. Weaning at SS7b is more appropriate without any curve progression cases immediately post-weaning for small curves (<40°). This makes reaching full fusion of both distal radius and ulna physis (SS8) not necessary and brace weaning can be initiated approximately 9.0 months earlier.