Multiple studies have shown that the final outcome in bracing is proportional to the number of hours the brace is worn and proportional to the amount of “in-brace correction” achieved (reduction in size of the curve when comparing the in-brace x-ray to the original x-ray). It is also impacted by several other factors. Once we have a pre-brace x-ray Cobb angle value and an in-brace x-ray Cobb value, we can apply formulas to predict the likely outcome.
Disclaimer
The outcomes calculation is provided for estimation only to show possible differences in outcomes depend on the variations in Daily Wear Time (DWT) and In-Brace Correction (IBC). An individuals actual outcome can and will vary from this predictive calculation.
Created By
Gez Bowman CO, MBAPO
References
“AIS progression peaks during the growth period and then slows and stabilizes, in most cases, toward the end of skeletal maturity”
Little DG, Song KM, Katz D, et al. Relationship of peak height velocity to other maturity indicators in idiopathic scoliosis in girls. J Bone Joint Surg Am. 2000;82(5):685-93.
“treatment success increased with longer hours of brace wear”
Weinstein, S.L.; Dolan, L.A.; Wright, J.G.; Dobbs, M.B. Effects of Bracing in Adolescents with Idiopathic Scoliosis. N. Engl. J. Med. 2013, 369, 1512–1521
“IBC has been proven to be a strong predictor of brace treatment failure”
Wong, L.P.K.; Cheung, P.W.H.; Cheung, J.P.Y. Curve Type, Flexibility, Correction, and Rotation Are Predictors of Curve Progression in Patients with Adolescent Idiopathic Scoliosis Undergoing Conservative Treatment: A Systematic Review. Bone Jt. J. 2022, 104, 424–432
“results confirm the relevant role of IBC in predicting the end of growth results”
Donzelli, S.; Fregna, G.; Zaina, F.; Livetti, G.; Reitano, M.C.; Negrini, S. Predictors of Clinically Meaningful Results of Bracing in a Large Cohort of Adolescents with Idiopathic Scoliosis Reaching the End of Conservative Treatment. Children 2023, 10, 719
“The most important predicting factors for treatment success are in-brace correction and compliance, followed by curve magnitude and early growth stage.”
Karavidas N. Bracing In The Treatment Of Adolescent Idiopathic Scoliosis: Evidence To Date. Adolesc Health Med Ther. 2019 Oct 8;10:153-172.
“Skeletal maturity and curve magnitude have strong predictive value for future curve progression.”
Johnson MA, Flynn JM, Anari JB, Gohel S, Cahill PJ, Winell JJ, Baldwin KD. Risk of Scoliosis Progression in Nonoperatively Treated Adolescent Idiopathic Scoliosis Based on Skeletal Maturity. J Pediatr Orthop. 2021 Oct 1;41(9):543-548.
“The type and quality of treatment applied, the compliance to treatment and the dosage of brace-wear are recognised as determinants of final results.”
Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Design of the Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST). Spine (Phila Pa 1976). 2013 Oct 1;38(21):1832-41.
“for progression over 40° the major predictor is Cobb degrees at start”
Donzelli S, Zaina F, Negrini S. Predicting scoliosis progression: a challenge for researchers and clinicians. EClinicalMedicine. 2020 Jan 6;18:100244.
“success rate of bracing is 70–75% subjected to initial brace correction quality, brace design, treatment compliance, adequate duration as well as clinical monitoring of X-ray at each clinical visit”
Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Design of the Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST). Spine (Phila Pa 1976). 2013 Oct 1;38(21):1832-41.
“Compliant patients with a high initial correction can expect a final correction of around 7 degrees, while compliant patients with low initial correction may maintain the curve extent. Bad compliance is always associated with curve progression.”
Landauer F, Wimmer C, Behensky H. Estimating the final outcome of brace treatment for idiopathic thoracic scoliosis at 6-month follow-up. Pediatr Rehabil. 2003 Jul-Dec;6(3-4):201-7.
“Overall, 81 patients (78%) obtained a curve correction, and stabilization was achieved in 14 cases (13%). Nine patients experienced curve progression (9%), 16 patients were recommended for surgery because the curve at follow up was over 45°.”
“The analysis of subgroups shows that with Cobb <45° at baseline, the average reduction was 11.46° Cobb, while in cases with Cobb ≥45 at baseline, the mean correction was 13.74° Cobb”
Aulisa AG, Guzzanti V, Falciglia F, Giordano M, Galli M, Aulisa L. Brace treatment of Idiopathic Scoliosis is effective for a curve over 40 degrees, but is the evaluation of Cobb angle the only parameter for the indication of treatment? Eur J Phys Rehabil Med. 2019 Apr;55(2):231-240.
“twenty-five patients [with average] Cobb angle: 49°…Two patients progressed, 12 patients were able to achieve halted progression, and eleven patients improved”
Weiss HR, Tournavitis N, Seibel S, Kleban A. A Prospective Cohort Study of AIS Patients with 40° and More Treated with a Gensingen Brace (GBW): Preliminary Results. Open Orthop J. 2017 Dec 29;11:1558-1567.
“at the end of [Cheneau] brace therapy, the primary Cobb angle was decreased by more than 5° in 27 patients (35%), unchanged (within the range of ±5°) in 36 patients (46%), and increased more than 5° in 15 patients (19%).”
Pepke W, Morani W, Schiltenwolf M, Bruckner T, Renkawitz T, Hemmer S, Akbar M. Outcome of Conservative Therapy of Adolescent Idiopathic Scoliosis (AIS) with Chêneau-Brace. J Clin Med. 2023 Mar 26;12(7):2507.
“17% of patients (98 of 586) had an improved angle and 40% of patients (234 of 586) had curve deterioration. In patients who improved, the mean reduction in the Cobb angle was 9 ± 4°”
Cheung JPY, Cheung PWH, Yeng WC, Chan LCK. Does Curve Regression Occur During Underarm Bracing in Patients with Adolescent Idiopathic Scoliosis? Clin Orthop Relat Res. 2020 Feb;478(2):334-345.
“Cohorts were similar at baseline but… average hours of brace wear: 18.31 in the ISICO versus 11.76 in the BrAIST cohort. Twelve percent of the ISICO and 39% of the BrAIST cohort had failed treatment.”
Dolan LA, Donzelli S, Zaina F, Weinstein SL, Negrini S. Adolescent Idiopathic Scoliosis Bracing Success Is Influenced by Time in Brace: Comparative Effectiveness Analysis of BrAIST and ISICO Cohorts. Spine (Phila Pa 1976). 2020 Sep 1;45(17):1193-1199.
Assumptions
weighting for IBC ~ proportional to weighting for DWT
Wear Time Hours are entered separately for day-time and night-time and specification needed for whether the in-brace x-ray is taken standing or supine. Based on authors experience an assumption is made that an IB standing x-ray is 20% more corrective in supine and an IB supine x-ray is 20% less corrective in standing.
Derivations
Info to follow