Preliminary results of prediction of brace treatment outcomes by monitoring brace usage

Objective

To determine whether brace treatment outcome can be predicted by brace usage in terms of wear time (quantity) and wear tightness (quality).

Study design

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.

Twenty AIS subjects (13.4 ± 1.8 years) prescribed Boston braces with full time brace wear were monitored for 2 weeks and followed-up for 3 years. A prediction of curve progression model was developed. The prediction model was tested on a new full time brace wearer (9.2 years old, female, AIS, 39° Cobb angle, Apex T8).

Hypothesis

Brace treatment outcome may be predicted from brace usage.

Results

The curve size of the 20 subjects prior to bracing was 32 ± 8°. While in the brace, the Cobb angle improved by 9 ± 6°. At skeletal maturity, after bracing, the Cobb angle was 4 ± 9° higher than prior to bracing. The quantity and quality of brace usage was recorded. The curve progression model was:

Curve Progression = 33 + 0.12*Peterson Risk(%) - 0.48*Quality(%) - 0.52*Quantity (%) +0.0066*Quantity*Quality.

The new subject had a Peterson Risk 73%, Quantity 80% and Quality 70%. The in-brace Cobb angle was 29°. At the 4 month visit, the predicted curve progression was 2° and the out of brace curve was 40° (1°different).

Conclusion

The quality and quantity of brace usage plus the risk progression factor may be able to predict brace treatment outcome.