Interesting but preliminary study on a predictive model of brace curve progression

Summary: Using a patient's individual risk of progressing (I'm guessing through some combination of Risser/Cobb angle, but the abstract doesn't say) and then recording after a month how well the brace fit and how many hours a day it was worn allowed the research to predict within +/- 3.5 degrees what the final curve size would be.

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http://www.ncbi.nlm.nih.gov/pubmed/1...,f1000m,isrctn

Preliminary validation of curve progression model for brace treatment.

Brace treatment is the most commonly used non-surgical treatment for adolescent idiopathic scoliosis (AIS). A brace compliance monitoring system consisting of a microcomputer and a force transducer was used to monitor how brace candidates used their braces during daily activates. A prediction model of the brace treatment outcome was developed based on 20 AIS subjects. Six subjects (1M, 5F) with AIS who had worn their braces for six weeks participated into this study. One month data was recorded during the study period. Knowing the risk progression at the beginning of brace treatment plus how brace subjects used their braces in terms of brace tightness and wear time during brace treatment yielded a predicted outcome which was compared to the final treatment outcomes with 2 years followed-up. This preliminary result demonstrated that the prediction model was able to predict the treatment outcome within +/-3.5 degrees.

Break out your calculators

I found the whole equation

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2793465/

Here are the factors:

**Peterson's risk progression**: risk of progression at the time when the brace was prescribed was calculated based on 4 variables: Risser sign, apex of the curve, age, and imbalance

**Flexibility**: (Initial Cobb - in-brace Cobb)/Initial Cobb (I think they're calling this in-brace correction in the formula)

**Quantity**: percent of wear time relative to the prescribed wear (22 hours a day is the prescribed wear)

**Quality**: percent of wear tightness relative to the prescribed tightness level

and the equation

curve Progression (in degrees) = 33 + 0.11*Peterson Risk (%) - 0.07 in-brace correction (%) - 0.45*Quality (%) - 0.48*Quantity (%) + 0.62*Quantity*Quality

I'm not sure where that constant (33) is coming from, though. Is that just their best guess of average correction after brace wear? Or do they plug in a different number for each kid based on the curve size when they started?

From the equation - time in brace and tightness are the big factors. Far more important then the starting risk or in-brace correction.