Introduction and objectives: Bracing design is mostly done using empirical methods. Recent advances in CAD/CAM and computer biomechanical simulations now allow designing, optimizing and fabricating novel generation of braces with expected biomechanical improvements. This study aims at comparing the effectiveness of these two brace design techniques for the treatment of adolescent idiopathic scoliosis (AIS).

Materials and methods: So far 7 AIS patients were recruited. Two braces were built for each patient: 1) a standard TLSO designed using the plaster-cast method (STD Brace), and 2) a brace designed and fabricated using a biomechanical 3D finite element model personalized to the patient's geometry and a CAD/CAM software (SimBrace). The latter technique allowed virtual installation of the brace on the patient model and prediction of its effects before fabrication. Several virtual braces were thus iteratively tested and the one giving the best immediate correction was chosen for refinement by the orthotist and fabricated using a computer-aided carver. Immediate brace effectiveness was assessed using radiographs in both braces.

Results: For the first patient, the STD Brace corrected the thoracic and lumbar Cobb angles by 52% and 40% respectively while SimBrace corrected these angles by 29% and 90%. There was little effect of the sagittal curves, and both braces maintained the coronal balance. The patient was more comfortable in the NewBrace.

Preliminary conclusion: These first results showed the feasibility of a new technique to design braces and assess their effectiveness with respect to current design technique. An extended study on more cases is under way to fully assess this new design paradigm.

Significance: When completely validated, this new design technique will allow improving the brace design process and rationalize conservative treatments of AIS.

Acknowledgements: Project funded by NSERC, Boston Brace and Lagarrigue. Special thanks to Benoît Bissonnette.