European Spine Journal - 2026-07-25 - Journal Article
Would initial thoracic correction be a key factor in orthotic intervention for adolescent idiopathic scoliosis with double-curve?
Zhou L, Liu S, Hassan Beygi B, Zou Y, Shang L, Ho LY, Wong MS
Topics
Key Takeaway
In double-curve AIS, high initial in-orthosis thoracic correction (≥38.3%) confers nearly 8-fold greater odds of treatment success, while thoracic curve progression accounts for 90.9% of all brace treatment failures.
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Summary
This retrospective study of 101 skeletally immature double-curve AIS patients treated with TLSO examined whether initial in-orthosis thoracic correction predicts final treatment success. Thoracic curves achieved significantly lower in-orthosis correction than TL/L curves (29.3% vs. 38.6%, p<0.001), and high thoracic correction (≥38.3%) was independently associated with treatment success (p=0.009) while TL/L correction was not (p=0.250). Five baseline radiographic predictors of high thoracic correction were identified—greater lumbar lordosis, thoracic and TL/L supine flexibility, lesser thoracic apical sagittal wedging, and smaller standing-to-supine RVAD increase—with a multivariable model AUC of 0.862.
Key Limitation
The 38.3% thoracic correction threshold was derived from the same cohort used to validate it, creating circularity that requires external prospective validation before clinical adoption.
Original Abstract
PURPOSE
To investigate the influence of in-orthosis correction on treatment outcomes of adolescent idiopathic scoliosis (AIS) with double-curve, and to explore baseline radiographic features associated with achieving high in-orthosis correction.
METHODS
This retrospective study analyzed 101 skeletally immature patients with double-curve AIS treated with customized thoracic-lumbar-sacral orthosis (TLSO). Radiographic measurements from pre-orthosis standing and supine, first in-orthosis, and final out-of-orthosis follow-up visits were analyzed. Initial in-orthosis correction rates for the thoracic and thoracolumbar/lumbar (TL/L) curves were compared. Patients were dichotomized into high (≥ 38.3%) and low (< 38.3%) thoracic correction groups. An exploratory multivariable analysis was performed to identify baseline radiographic features associated with thoracic correction outcomes.
RESULTS
Thoracic curves had significantly lower initial in-orthosis correction than TL/L curves (29.3% vs. 38.6%, p < 0.001). High initial thoracic correction was strongly associated with final treatment success for the thoracic curve (p = 0.009), whereas TL/L curve correction was not (p = 0.250). Thoracic curve progression accounted for 90.9% of treatment failures. Patients who achieved high thoracic correction had nearly eight times the odds of achieving high TL/L correction (OR = 7.89, 95% CI: 2.97-20.90). Five radiographic factors were found to be associated with high correction: greater pre-orthosis lumbar lordosis, higher thoracic and TL/L supine flexibility, lesser thoracic apical sagittal wedging, and a smaller increase in rib-vertebral angle difference (RVAD) from standing to supine. The model showed good discriminatory capacity within the cohort (AUC = 0.862).
CONCLUSION
In AIS with double-curve, inadequate in-orthosis thoracic correction is strongly associated with treatment failure. A set of baseline radiographic features including favorable sagittal alignment, high flexibility, and rib cage stability are associated with successful thoracic correction, generating hypotheses regarding potential biomechanical factors for this limitation which can also serve as a foundation for future research.