A new 46-patient study from a team in Hong Kong has new data regarding how axial plane parameters may affect adolescent idiopathic scoliosis (AIS) bracing outcomes. Their study, “Brace Effectiveness Is Related to 3-Dimensional Plane Parameters in Patients with Adolescent Idiopathic Scoliosis,” appears in the January 6, 2021 edition of The Journal of Bone and Joint Surgery.
How Critical Is Axial Plane Effect to AIS Bracing Success?
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#adolescentidiopathicscoliosisSecondary#apicalverticalrotation
Looking at the Often Overlooked Axial Plane Effect of Bracing
Kenny Yat Hong Kwan, BM BCh(Oxon), FRCSEd(Orth), FHKCOS, FHKAM(Orth) clinical assistant professor in the Department of Orthopaedics and Traumatology at Li Ka Shing Faculty of Medicine at The University of Hong Kong explained to OTW the issue that he and his colleagues were hoping to understand better, “I have noticed from my patients and from the literature that bracing effectiveness was between 70-80% despite good compliance. Traditional risk factors mostly were not modifiable or only related to the coronal plane. However, scoliosis is a three-dimensional deformity, and I believe that braces that are able to control the axial plane may be a factor in brace success. Yet no prospective study has looked into this field.”
The study collected data from patients beginning when they started wearing a brace through at least two years of followup or until surgery. An EOS imaging system was used to reconstruct 3D images prior to bracing, at bracing, one year in bracing, and their latest followup once the brace was removed. Patients were required to wear the brace an average of 12.9 hours each week.
Moving the Needle on Curve Correction
According to Dr. Kwon, the study found that, “Pre-brace apical vertical rotation, an axial plane parameter, was worse in patients who ultimately had curve progression. Apical vertical rotation correction velocity during brace was predictive of curve progression on multiple linear regression analysis. This suggests that braces that are able to control scoliosis in the axial plane results in better curve control during bracing.”
“Axial plane correction should be determined during bracing in follow-up visits, so modification of brace designs can be initiated to control the axial plane parameters and decrease the risk of curve progression during bracing. Future studies on brace designs to incorporate 3-dimensional correction are warranted.”
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Discussion
This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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