• Frank P Castro.
• Spine Surgery, PSC, 210 East Gray Street, Suite 601, Louisville, KY 40202, USA.
• Spine J. 2003 May 1; 3 (3): 180-5.

Background ContextEvidence demonstrating the biomechanical effects of the Hueter-Volkmann principle on vertebral body growth in spinal deformities is lacking. Bracing a scoliotic curve should, in theory, unload the growth plates on the concave side of the vertebral bodies near the curve's apex. Growth stimulation, leading to structural remodeling of the vertebral bodies, on the curve's concave side may explain the improvement or lack of curve progression, as measured by Cobb angles, reported with successful brace management of adolescent idiopathic scoliosis (AIS).PurposeTo determine whether brace treatment stimulated asymmetric chondrogenesis in the apical three vertebral bodies.Study DesignA prospective cohort of patients with AIS receiving brace treatment were followed from the initiation of brace treatment until skeletal maturity. Patients were then retrospectively divided into those with and without radiographic progression. This post hoc analysis was included to determine risk factors for curve progression.Patient SampleForty-one skeletally immature patients with AIS meeting criteria for brace treatment were followed until skeletal maturity. All patients were treated with thoracolumbosacral orthotics (TLSOs).Outcome MeasuresThe positional derotation of the TLSO on the spine was measured by comparing the initial radiograph with the first radiograph in a brace. The long-term structural changes of the vertebral bodies were determined by comparing the initial and final radiographs. Differences in initial radiographic parameters between the groups of patients with AIS with and without curve progression indicated predictive factors for successful brace treatment.MethodsInitial radiographic measurements were compared with those observed in a brace and those observed at final follow-up. The same analysis was retrospectively repeated comparing patients with AIS with and without radiographic progression.ResultsCobb measurements (p=.0001) and concave-to-convex height ratios of the apical three vertebral bodies improved when the brace was initially applied (p=.0035). Structural remodeling or a rotational correction of the apical three vertebral bodies was appreciated only in patients with flexible curves (p=.01).ConclusionBrace application results in immediate positional derotations of the spine in patients with AIS. These positional derotations were maintained only in patients with flexible curves, at final follow-up. Brace treatment was not recommended in patients whose curves did not correct at least 20% in a TLSO.

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